JP4728717B2 - Autonomous storage apparatus, autonomous storage system, distributed storage system, load distribution program, and load distribution method - Google Patents

Description

  The present invention relates to an autonomous storage device, an autonomous storage system, a distributed storage system, a load distribution program, and a load distribution method capable of distributing an access load when content (data) is distributed and stored on a network.

  In recent years, the amount of content data used in computers continues to increase, and along with this, the capacity of storage devices (storage) such as hard disks for storing content has also increased. However, since the storage device may fail, content loss due to the storage device failure increases with an increase in the capacity of the storage device. Therefore, recently, an autonomous storage system has been proposed as a technique for improving the reliability, safety, availability, and expandability of a storage device (see, for example, Non-Patent Document 1).

  In this autonomous storage system, a plurality of autonomous storage devices connected to a network exchange load information, failure information, etc. of the devices via the network, and based on predetermined autonomous distributed management rules, The content is copied and moved in cooperation with the storage apparatus. Thus, in the autonomous storage system, in addition to load distribution and failure recovery when storing content, the autonomous storage apparatus can be expanded and removed. In general, moving content (data) in order to realize load distribution or the like is called migration.

Here, with reference to FIG.11 and FIG.12, the load distribution method by the migration in the conventional autonomous storage system is demonstrated. FIG. 11 is a flowchart showing the load balancing operation in the conventional autonomous storage system. FIG. 12 is a flowchart showing the detailed operation of the migration process in FIG.
Here, the process means a group of a plurality of related processes as one processing unit. These processes can coexist in one autonomous storage apparatus and operate in parallel. A process has a unique identifier in the system, and is distinguished from other processes by the identifier. Also, the process can operate across multiple autonomous storage devices.
As shown in FIG. 11, in the conventional autonomous storage system, each autonomous storage device detects a load state and is overloaded between a plurality of autonomous storage devices connected to the network exceeding a set threshold. The autonomous storage device is determined (step S50). Then, the autonomous storage system determines the content (strategy) of the migration such as the transfer source content and the transfer destination when performing the migration (step S51).

  Then, the autonomous storage system executes a migration process for one content based on the determined migration content (step S52). Furthermore, when there is content to be migrated (“Yes” in step S53), the autonomous storage system continues to execute the migration process in step S52, and there is no content to be migrated ( In step S53, “None”), the process ends. As a result, the migration-source autonomous storage apparatus is released from the overload state, and the access load for each autonomous storage apparatus constituting the autonomous storage system is balanced.

Here, the operation of the “migration process” in step S52 will be described in detail with reference to FIG.
As shown in FIG. 12, here, from a certain autonomous storage device 2B _S, the autonomous storage device 2B _T, the contents of the migration to move content is assumed to have been determined in the step S51 (see FIG. 11).

First, over the autonomous storage device 2B _S, together with the content (target content) to be targeted for migration will identify the file name or the like, sequentially shared lock on partial information for identifying the content of interest (index information) (Step S60). Moreover, the autonomous storage device 2B _S share lock the target content (step S61). Here, the shared lock allows the reference (reading process) to the information from other than the process (here, the migration process) that performs the locking process on information such as index information and content. , Insert, update, delete, etc. (write processing) operations are prohibited locks. Here, it is assumed that the shared lock state is inherited to the content transfer destination or copy destination.

Then, the autonomous storage device 2B _S transfers a copy of the target content to the transfer destination autonomous storage device 2B _T (step S62). Then, the autonomous storage device 2B _T receives and stores a copy of the transferred target content (step S63).
Then, the autonomous storage device 2B _S is exclusive lock the target content and the index information (step S64). Here, the exclusive lock refers to a lock that prohibits all reference, insertion, update, and deletion operations on the information (index information and target content) from other than the process. Here, it is assumed that the exclusive lock state is inherited to the content transfer destination or copy destination.

Then, the autonomous storage device 2B _S deletes the target content information (identification information) from the index information (step S65). On the other hand, the autonomous storage device 2B _T inserts information of the target content to the index information (step S66). As described above, when the information of the target content is inserted into the index information, it is possible to access the target content by following the index information from other than the process.
At the stage of updating has been completed for the index information, the autonomous storage device 2B _S releases all shared lock and an exclusive lock is applied to the target content and the index information (step S67), deletes the target content (step S68 ).
With the above operation, even when the autonomous storage system is operating, content can be moved between the autonomous storage devices.

Next, a migration operation in the conventional autonomous storage system will be described with a specific example with reference to FIG. FIG. 13 is a schematic diagram showing a migration operation in a conventional autonomous storage system. Here, a state in which contents (C1 to C16, C′1 to C′16) are stored in the autonomous storage apparatus 2B (2B _{1 to} 2B ₄ ) constituting the autonomous storage system is shown. Note that the contents C′1 to C′16 are duplicates (duplicate contents) of the contents C1 to C16.

Here, the mobile as shown in FIG. 13 (a), and concentrated access to the autonomous storage device 2B _2, the autonomous storage system, to the autonomous storage apparatus 2B ₄ from the autonomous storage devices 2B _2, the content C7 and C8 Suppose you decide to
Then, as shown in FIG. 13B, the autonomous storage system moves the content C8 from the autonomous storage apparatus 2B ₂ to the autonomous storage apparatus 2B ₄ while performing lock control according to the procedure described in FIG. 11 and FIG. Let

Furthermore, as shown in FIG. 13C, the autonomous storage system moves the content C7 from the autonomous storage device 2B ₂ to the autonomous storage device 2B ₄ while performing lock control. Incidentally, during the movement of the content C7, access to the content C8 already moved, it is performed to the autonomous storage apparatus 2B _4.

Then, after moving the content C7, autonomous storage system, as shown in FIG. 13 (d), access to the content C7, and C8 are will be made to an autonomous storage apparatus 2B _4, FIG. 13 (a ), The access concentrated on the autonomous storage device 2B ₂ is distributed to the autonomous storage device 2B ₄ , and the access load is balanced.
"Haruo Yokota," Autonomous Disks for Advanced Database Applications ", In Proc. Of International Symposium on Database Applications in Non-Traditional Environments (DANTE'99), pages 441-448, Nov, 1999.

  In the conventional technology described above, in an autonomous storage system, in order to balance the access load on the autonomous storage device, it is necessary to move content from the autonomous storage device in which the access load is concentrated. This movement of content is performed using the access capability of the autonomous storage device (or a storage device such as a hard disk that is a component thereof) and the bandwidth of the network to which the autonomous storage device is connected.

For this reason, there has been a problem that content cannot be transferred when the access capacity of the autonomous storage device (storage device) or the bandwidth of the network is saturated due to sudden concentration of access. Further, in this state, there are problems such as a delay in response to a content request from a user, and a response itself cannot be performed.
In order to solve this problem, it is conceivable to move content while the concentration of access load is small. However, in this case, the frequency of moving the content increases, access to the autonomous storage device (storage device) and network transfer increase, and the throughput of the entire autonomous storage system decreases. There is.

  The present invention has been made in view of the above problems, and in an autonomous storage system, the access load to a certain autonomous storage device is concentrated, and in order to distribute this access load, content is distributed to other autonomous storage systems. When moving (migration) to a storage device, resources (network bandwidth, etc.) associated with the movement of that content can be secured, and a decrease in throughput of the entire system can be prevented. It is an object to provide a storage system, a load distribution program, and a load distribution method.

The present invention was created to achieve the above object. First, the autonomous storage device according to claim 1 is a copy of the original content and the original content stored in another autonomous storage device. In an autonomous storage device in an autonomous storage system in which a plurality of autonomous storage devices that store replicated content are connected via a network , content storage means, load state detection means, moving content setting means, distribution rate setting means, The access distribution means and the content movement means are provided.

According to such a configuration, the autonomous storage device stores the original content in the content storage means and the duplicate content corresponding to the content (original content) stored in another autonomous storage device connected to the network.
The content used here may be a semantic summary of data stored in the autonomous storage device, such as a program or a document file, or only a part of the data such as a program or a document file is extracted. It may be a thing.
Then, the autonomous storage devices, the load state detection means, based on the access status to the autonomous storage equipment, for detecting the load state. At this time, the load state detection unit can recognize which autonomous storage device the access load is concentrated on by cooperating with the load state detection unit of all autonomous storage devices connected to the network. .

The autonomous storage device also moves original content (migration target content) to be moved from the plurality of original contents to another autonomous storage device based on the load state detected by the load state detection unit by the moving content setting unit. Set.
Then, the autonomous storage device, by the distribution ratio setting means, based on the access status to the stored original content to the autonomous storage equipment, to set the distribution ratio of the access.

Then, the autonomous storage device responds to the original content by the access distribution unit according to the distribution rate set by the distribution rate setting unit among the access to the autonomous storage device in which the migration target content is stored. Distribute the replicated content to other autonomous storage devices that store it. As a result, the access load to the content for movement is applied to the duplicate content, and the access load to the autonomous storage device is reduced.
Furthermore, the autonomous storage apparatus, after the access distribution is started at the distribution rate set by the distribution rate setting unit in the access distribution unit, the original content (content to be migrated) set by the content transfer unit by the content moving unit. ) To another autonomous storage device. As a result, access to the autonomous storage apparatus is distributed.

The autonomous storage apparatus according to claim 2 is the autonomous storage apparatus according to claim 1, further comprising a cache memory and a cache determination unit, wherein the access distribution unit is configured to perform the cache memory based on the distribution rate. The content is distributed preferentially to other autonomous storage devices from the original content that did not exist.

According to such a configuration, the autonomous storage device predicts and temporarily stores content that is likely to be accessed next in advance in the cache memory, and the cache determination unit stores the content of the original content in the cache memory. Determine whether data exists. Then, the autonomous storage apparatus preferentially distributes the access from the original content that did not exist in the cache memory to the other autonomous storage apparatuses by the access distribution means according to the distribution ratio.
As a result, the autonomous storage apparatus directly accesses the contents in which the content data exists (hits) in the cache memory by the autonomous storage apparatus.

  Furthermore, the autonomous storage device according to claim 3 is the autonomous storage device according to claim 1 or 2, wherein the moving content setting unit has a value indicating the load state exceeding a predetermined threshold. The original content to be moved to another autonomous storage device is set.

  According to such a configuration, when the autonomous storage device detects the load state, it only distributes the access until the value indicating the load state reaches a certain amount (threshold), and the amount exceeds the certain amount. In addition, the content can be moved.

In addition, the autonomous storage system according to claim 4 connects a plurality of autonomous storage apparatuses that store original contents and duplicate contents that are duplicates of original contents stored in other autonomous storage apparatuses via a network. In the autonomous storage system, the autonomous storage device includes a content storage unit, a load state detection unit, a moving content setting unit, a distribution rate setting unit, an access distribution unit, and a content moving unit. .

  According to this configuration, the autonomous storage system, in each autonomous storage device connected via the network, duplicates corresponding to the original content in the content storage means and the content (original content) stored in another autonomous storage device Store content. Then, the autonomous storage system detects to which autonomous storage device the access load is concentrated by the load state detection means of the autonomous storage device.

Furthermore, in the autonomous storage system in which the access load is concentrated, another autonomous storage apparatus is selected from a plurality of original contents according to the load state detected by the load state detection means by the moving content setting means. Set the original content to be moved to. In the autonomous storage apparatus, the distribution ratio setting means sets the access distribution ratio according to the access status to the original content, and the access distribution means stores the access distribution ratio in the autonomous storage apparatus according to the set distribution ratio. A part of the access to the original content is distributed to another autonomous storage device storing the duplicate content corresponding to the original content.
Then, the autonomous storage system starts distribution of access according to the distribution rate set by the distribution rate setting unit by the access distribution unit of the autonomous storage apparatus in which the access load is concentrated, and then by the content moving unit, The migration target content is moved to another autonomous storage device. As a result, the access load of each autonomous storage device constituting the autonomous storage system is distributed.

Further, the load distribution program according to claim 5 is a program for storing an autonomous storage device including content storage means for storing original content and a duplicate content that is a copy of the original content stored in another autonomous storage device. In order to distribute the load of the autonomous storage device in an autonomous storage system connected via a plurality of devices, a computer that controls the autonomous storage device is connected to a load state detection means, a moving content setting means, a distribution rate setting means, an access distribution means. The content moving means is configured to function.

According to such a configuration, the load balancing program, the load state detection means, based on the access status to the autonomous storage equipment, for detecting the load state.
Further, the load distribution program uses the moving content setting unit to move the original content (migration target content) from the plurality of original contents to another autonomous storage device based on the load state detected by the load state detecting unit. Set.
Then, the load balancing program, by the distribution ratio setting means, based on the access status to the stored original content to the autonomous storage equipment, to set the distribution ratio of the access.

Then, the load distribution program responds to the original content by the access distribution unit according to the distribution rate set by the distribution rate setting unit among the access to the autonomous storage apparatus in which the migration target content is stored. Distribute the replicated content to other autonomous storage devices that store it.
Further, the load distribution program moves the original content (content to be migrated) set by the moving content setting unit to another autonomous storage apparatus after the distribution of access is started by the access distributing unit by the content moving unit. . As a result, access to the autonomous storage apparatus is distributed.

The load distribution method according to claim 6 connects a plurality of autonomous storage apparatuses that store original contents and duplicate contents that are duplicates of original contents stored in other autonomous storage apparatuses via a network. In an autonomous storage system, a load distribution method for distributing loads among the autonomous storage devices, comprising a load state detection step, a moving content setting step, a distribution rate setting step, an access distribution step, and a content movement step The procedure included.

According to this procedure, the load distribution method in a load state detection step, based on the access status to the autonomous storage equipment, for detecting the load state. Then, in the moving content setting step, based on the load state, the original content (migration target content) to be moved to another autonomous storage device is set from the plurality of original contents.
The load distribution method in the distribution ratio setting step, based on the access status to the stored original content to the autonomous storage equipment, to set the distribution ratio of the access.
In the load distribution method, the access according to the distribution rate set in the distribution rate setting step among the access to the autonomous storage device in which the migration target content is stored corresponds to the original content in the access distribution step. Distributed to other autonomous storage devices storing the copied content.
Subsequently, in the load distribution method, in the content movement step, the original content set in the movement content setting step is moved to another autonomous storage device.

Furthermore, the distributed storage system according to claim 7 controls a plurality of storage devices that store the original content and a duplicate content that is a copy of the original content stored in another storage device, and the plurality of storage devices. A distributed storage system in which a controller is connected via a network, the controller comprising: a load state detecting means; a moving content setting means; a distribution rate setting means; an access distributing means; and a content moving means. It was set as the structure provided.

According to such a configuration, the distributed storage system, the load state detection means in the controller, based on the access status to the storage equipment, to detect the load state of the storage device. Alternatively, the load state detected in the storage device is acquired.
The distributed storage system then moves the original content (migration target content) to be migrated from the plurality of original contents to another storage device based on the load state detected by the load state detection unit by the moving content setting unit. Set.
Further, the distributed storage system distributes access from the storage device to another storage device to which the original content is moved based on the access status to the original content stored in the storage device by the distribution rate setting means. Set.

Then, the distributed storage system copies a part of the access to the storage device by the access distribution unit corresponding to the original content stored in the storage device based on the distribution rate set by the distribution rate setting unit. Distribute content to other storage devices. As a result, the access load to the original content is applied to the copied content, and the access load to the storage device storing the original content is reduced.
Then, the distributed storage system moves the original content set by the moving content setting unit to another storage device after distribution of access is started by the content moving unit.
The distributed storage system may set the migration target content only when the load state exceeds a predetermined threshold (load threshold) in the moving content setting unit.

Further, the distributed storage system according to claim 8 is the distributed storage system according to claim 7, wherein the controller corresponds to the original content stored in the original content and another storage device connected to the network. The content storage means for storing the copied content to be stored is provided.
According to such a configuration, the distributed storage system includes the content storage unit in the controller as well as other storage devices, thereby increasing the storage capacity of the content of the entire system or realizing higher distribution performance. It becomes possible to do.

  According to the present invention, when an access load is concentrated on a certain autonomous storage device, the access load can be distributed to other autonomous storage devices. At this time, according to the present invention, access is temporarily distributed to the autonomous storage device storing the duplicate content corresponding to the original content, and the content is moved. There is room. Therefore, even when the access load is concentrated, there is no possibility that the response to the content request from the user is delayed or the response itself cannot be made.

Further, according to the present invention, since content that does not exist in the cache memory is preferentially distributed to other autonomous storage devices, it is possible to suppress a decrease in the cache memory hit rate in the autonomous storage device.
Furthermore, according to the present invention, since the content is moved when the value indicating the load state exceeds a predetermined threshold value, the frequency of the content movement accompanied by the network transfer is reduced, and the throughput is improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Configuration of autonomous storage system]
First, the configuration of the autonomous storage system according to the present invention will be described with reference to FIG. FIG. 1 is a schematic block diagram showing the configuration of an autonomous storage system.
As shown in FIG. 1, the autonomous storage system 1 includes a plurality (four as an example) of autonomous storage devices 2 (2 ₁ to 2 ₄ ) connected to a network N. In this autonomous storage system 1, content is distributed and stored in each autonomous storage device 2 (2 ₁ to 2 ₄ ), and writing and reading are access to the content from a client computer 5 or the like connected to the same network N. It responds to requests such as.

Here, the autonomous storage device 2 includes a system management unit 20 and a content storage unit 30 (details will be described later), and the system management unit 20 cooperates with other autonomous storage devices. Thus, the content is stored in the content storage unit 30 so as to balance the access load.
The autonomous storage device 2 stores the original content and a duplicate content that is a duplicate of the original content stored in another autonomous storage device in its own content storage means 30.
Here, the autonomous storage device 2 is assumed to store the original content Cn and the duplicate content C′n as shown in the example of FIG. 1 as a state before the access load is concentrated.
If the original content and the duplicate content are associated with each other, the duplicate content may be stored in any autonomous storage device other than the autonomous storage device storing the original content.

(Configuration of autonomous storage system)
Next, a configuration of the autonomous storage apparatus according to the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing a configuration of the autonomous storage apparatus.
As shown in FIG. 2, the autonomous storage apparatus 2 includes a communication transmission / reception unit 10, a system management unit 20, a content storage unit 30, and an index information storage unit 40.

  The communication transmitting / receiving means 10 transmits / receives data to / from a client computer or other autonomous storage apparatus (see FIG. 1) via the network N. For example, the communication transmitting / receiving means 10 is a communication board that transmits and receives data using a TCP / IP (Transmission Control Protocol / Internet Protocol) communication protocol.

  The system management means 20 controls the entire autonomous storage apparatus 2. For example, the system management means 20 is a computer having a CPU (Central Processing Unit), a memory, etc., and by causing the program to function as each means shown below, in cooperation with other autonomous storage devices, Access load is distributed. Here, the system management means 20 includes content storage means 21, content distribution means 22, content deletion means 23, control information reception means 24, control information transmission means 25, content management means 26, and access distribution means. 27.

  The content storage unit 21 acquires content (original content or duplicate content) via the communication transmitting / receiving unit 10 and stores the content in the content storage unit 30. The content storage unit 21 includes a content reception unit 21a and a content writing unit 21b. Yes.

  The content receiving unit 21 a receives the content acquired via the communication transmitting / receiving unit 10. The content receiving unit 21a receives content from a content transmission source (for example, a client computer or other autonomous storage device) notified from the content operation control unit 263 of the content management unit 26, which will be described later, via the communication transmitting / receiving unit 10. Receive. The content received here is output to the content writing means 21b.

  The content writing unit 21b writes the content received by the content receiving unit 21a into the content storage unit 30 as the original content 30a or the duplicate content 30b of the content storage unit 30. The content writing unit 21 b writes the content into the content storage unit 30 based on the position information (address) notified from the content operation control unit 263 of the content management unit 26. Note that the content management unit 26 manages whether the content written in the content storage unit 30 is the original content 30a or the copied content 30b.

  The content distribution unit 22 distributes the content (original content 30a or duplicate content 30b) stored in the content storage unit 30 via the communication transmitting / receiving unit 10, and includes a content reading unit 22a and a content transmission unit 22b. It has.

  The content reading unit 22a reads the content (original content 30a or duplicate content 30b) stored in the content storage unit 30. The content reading unit 22 a reads the content from the content storage unit 30 based on the position information (address) notified from the content operation control unit 263 of the content management unit 26. The content read here is output to the content transmission means 22b.

  The content transmitting unit 22b transmits the content read by the content reading unit 22a via the communication transmitting / receiving unit 10. The content transmission unit 22b transmits the content via the communication transmission / reception unit 10 to the transmission destination of the content notified from the content operation control unit 263 of the content management unit 26 (for example, a client computer, another autonomous storage device). To do.

  The content deletion unit 23 deletes the content (original content 30a or duplicate content 30b) stored in the content storage unit 30. The content deletion unit 23 deletes the instructed content from the content storage unit 30 based on the position information (address) notified from the content operation control unit 263 of the content management unit 26.

The control information receiving unit 24 receives control information that is data other than content from a client computer, another autonomous storage device (see FIG. 1), and the like via the communication transmitting / receiving unit 10. The control information received here is output to the access distribution means 27.
Here, the control information is information for the autonomous storage device 2 to operate in cooperation with other autonomous storage devices. For example, a content storage instruction that indicates that content is to be stored (written), a content distribution instruction that indicates that content is to be distributed (read), a content deletion instruction that indicates that content is to be deleted, and a load state that indicates a load status notification This is a notification instruction, an access control instruction indicating a lock process for content and its release, a response to these instructions, or the like.

  The control information transmission unit 25 transmits the control information output from the access distribution unit 27 to the client computer, another autonomous storage device (see FIG. 1), and the like via the communication transmission / reception unit 10.

  The content management unit 26 manages content based on the control information received by the control information receiving unit 24. The content management unit 26 distributes access to the autonomous storage device 2 to other autonomous storage devices when the autonomous storage device 2 is overloaded. Here, the content management unit 26 includes a control information analysis unit 261, a content movement unit 262, and a content operation control unit 263.

The control information analyzing unit 261 analyzes the control information received by the control information receiving unit 24 and executes a process corresponding to the control information. For example, when a content storage instruction, a content distribution instruction, or a content deletion instruction is instructed as control information, the control information analysis unit 261 outputs the fact to the content operation control unit 263.
Further, here, the control information analysis unit 261 includes a load state detection unit 261a, a moving content setting unit 261b, a distribution rate setting unit 261c, an access control unit 261d, and a cache determination unit 261e.

  The load state detection means 261a detects the load state of the autonomous storage device 2 and recognizes the load state of other autonomous storage devices. For example, the load state detection unit 261a detects its own load state based on the access status such as the number of accesses to the original content 30a per unit time and the number of transfer bytes. Further, the load state detection unit 261a acquires the load state of the other autonomous storage device from the other autonomous storage device as control information. Thereby, the load state detection unit 261a can grasp the load states of all the autonomous storage apparatuses 2 connected to the network N.

  The moving content setting unit 261b sets content (migration target content) to be moved from the plurality of original contents 30a to another autonomous storage device based on the load state detected by the load state detecting unit 261a. is there. Then, the moving content setting unit 261b sets the identification information 40a of the original content 30a set as the migration target content and the position (association information) of the other autonomous storage device in which the duplicate content corresponding to the original content 30a is stored. 40b) to the access control means 261c and to the access distribution means 27.

  Furthermore, the moving content setting unit 261b determines the destination of the migration target content. The destination is preferably other than the autonomous storage device that stores the copied content. This is because the original content and the duplicate content corresponding to the original content are distributed to enable failure recovery in the event of a failure. Then, the moving content setting unit 261 b outputs the migration target content identification information 40 a and the position of the destination autonomous storage device to the content moving unit 262.

  The moving content setting unit 261b may set the migration target content only when the load state exceeds a predetermined threshold (load threshold). In this case, for example, the load threshold is set to twice the load average of the entire autonomous storage system 1 (FIG. 1).

Here, when the node number of a certain autonomous storage device is i, the load on the original content 30a at time t is LP _i (t), and the load on the duplicate content 30b is LB _i (t), the node number i The load is LP _i (t) + LB _{i + 1} (t) + LB _i (t).
Therefore, when the load average of the entire autonomous storage system 1 (FIG. 1) is _Lavg (t), the moving content setting unit 261b needs to migrate at time t + 1 in the following equation (1). Judge.
LP _i (t) + LB _{i + 1} (t) + LB _i (t)> 2 × L _avg (t) (1)

When the performance of each autonomous storage device is different and the average load greatly exceeds the performance of a certain autonomous storage device, the value of _Lavg (t) on the right side of the equation (1) is set low beforehand. deep. Further, when the load of each autonomous storage apparatus is large, but the average load is low, the maximum value on the left side of the equation (1) is used as the criterion for migration determination.

The distribution rate setting unit 261c sets the access distribution rate based on the access status to the original content set by the moving content setting unit 261b. The distribution rate set by the distribution rate setting unit 261c is output to the access distribution unit 27.
For example, the distribution rate setting unit 261c sets the access load for the autonomous storage device 2 to W [Byte], and sets the access load required for migration of the migration target content set by the moving content setting unit 261b to d [Byte]. At this time, the distribution ratio r shown in the following equation (2) is distributed to other autonomous storage apparatuses.
r = d / W (2) formula

Here, with reference to FIG. 3 (refer to FIG. 2 as appropriate), a migration target content setting method in the moving content setting unit 261b and a distribution rate setting method in the distribution rate setting unit 261c will be described. FIG. 3 is an explanatory diagram for explaining a migration target content setting method and a distribution rate setting method. FIG. 3A shows a state where access loads are concentrated in an autonomous storage system. (B) shows the state after the migration target content is moved.
FIG. 3 shows a state in which contents (original contents) are stored in each of the autonomous storage apparatuses 2 ₁ to 2 ₄ by range division, and the content number is shown for each autonomous storage apparatus 2 ₁ to 2 ₄ from the left in the figure. C, content size S, access number A per unit time, and access load (content size S × access number A).

In FIG. 3 (a), the access load L of each autonomous storage devices 2 ₁ to 2 per ₄ each "9", "3", "5", and a "3", the autonomous storage system 2 ₁ Access load is concentrated. Therefore, the moving content setting unit 261b sets the moving content (migration target content) so as to average the access load L of each of the autonomous storage apparatuses 2 ₁ to 2 ₄ .

Specifically, the mobile content setting means 261b first adds a value (“9” + “3” + “5” + “3” = “9”) to each of the autonomous storage apparatuses 2 ₁ to 2 _4. 20 ”) is divided by the number of autonomous storage apparatuses (here,“ 4 ”) to calculate the average value (“ 5 ”) of the access load L. The mobile content setting unit 261b is the content C2 and C3, it is moved from the autonomous storage system 2 ₁ autonomous storage devices 2 _2, the content C5, move from the autonomous storage system 2 ₂ the autonomous storage unit 2 _3, further , the setting of the content C8, moving from the autonomous storage system 2 ₃ autonomous storage apparatus 2 _4. Thus, by moving the migration target content set by the moving content setting means 261b, as shown in FIG. 3B, the access load L for each of the autonomous storage apparatuses 2 ₁ to 2 ₄ is “ 5 "and the concentration of access load can be balanced.

Note that when the migration target content is moved, an additional access load is generated due to this movement. For example, the autonomous storage device 2 _1, when moving the content C2 and C3, as requiring two units of time the movement, content size S is the content C2 is "2", content size S is "1" In order to move a certain content C3, a load of (2 + 1) /2=1.5 occurs due to the movement. Thus, the autonomous storage system 2 _first access load L becomes "9" + "1.5" = "10.5".

Here, if the autonomous storage device 2 _1, the client computer (see FIG. 1) service without delay to a request from the access load continues is "10", the autonomous storage device 2 _1, movement of the migrated content This makes it difficult to continue the service.
Therefore, the distribution ratio setting unit 261c is a part of access to autonomous storage device 2 _1, sets the distribution ratio for distributing the autonomous storage device storing the copied content.
Specifically, the distribution ratio setting unit 261c, since access load W with respect to the autonomous storage system 2 ₁ "9", the access load d to move the migration target content is "4", the "d / W" A certain “4/9” is set as an access distribution rate. Thus, the access load on the autonomous storage system 2 ₁ reduced to 9 × (1-4 / 9) + 1.5 = 6.5, so that the access capability for moving the migration target contents is ensured.

In this example, the distribution rate is set to “d / W”, but the moving content setting unit 261b is determined to move the content migrated from the adjacent autonomous storage device to another autonomous storage device. Therefore, the distribution ratio r is desirably “1” at the maximum as shown in the following equation (3).
r = min (1.0, d / W) (3) formula

Further, the distribution ratio setting unit 261c, as the method of setting the other distribution ratio, the autonomous storage system 2 ₁ Lt access load on [Byte / s], the movement of the migrated content that is set in the mobile content setting means 261b Lm [Byte / s] access load required for, when the allowable value of the autonomous storage system 2 _first access load was P [Byte / s], the following equation (4), sets the distribution ratio r It is good as well.
r = (Lt + Lm) −P) / Lt (4)

Note that the content to be migrated from the adjacent autonomous storage device may be determined to be moved to another autonomous storage device in the moving content setting unit 261b. Is desirable.
r = min (1.0, max (0, ((Lt + Lm) −P) / Lt)) (5)

  If the access load in the distribution-destination autonomous storage device exceeds the allowable value as a result of distributing the access load to the distribution-destination autonomous storage device at the distribution rate set in the distribution rate setting means 261c, the distribution-destination autonomous storage device Access to the original content of the device may be distributed to other autonomous storage devices that store a copy of the original content of the distribution-destination autonomous storage device.

Note that the distribution rate setting unit 261c may set the content to be distributed in descending order of access frequency according to the distribution rate, or may set only the distribution rate.
Further, the distribution rate setting unit 261c may preferentially set the content to be distributed from the content that did not hit the cache memory (not shown) according to the distribution rate by the cache determination unit 261e described later. .

Specifically, the distribution rate setting unit 261c has a miss rate when the cache memory hit rate for the original content 30a stored in the content storage unit 30 of the autonomous storage device 2 is h and the distribution rate is r. When (1-h) is lower than the distribution ratio r, if the following expression (6) is satisfied, the content is targeted for distribution, and if not satisfied, the content is not targeted for distribution.
rand () <r / (1-h) (6)

On the other hand, when the miss rate (1-h) exceeds the distribution rate r, if the following expression (7) is satisfied, the content is set as a distribution target, and if not satisfied, it is not set as a distribution target.
rand ()> (r + h−1) / h (7) In the expressions (6) and (7), rand () indicates a pseudo random number generation function.
As a result, when setting the content to be distributed, the cache effect in the autonomous storage device 2 can be enhanced, and a decrease in the cache hit rate in the destination autonomous storage device can be prevented. Further, when only the distribution rate is set, it is not necessary to specify the content to be accessed in the source autonomous storage device.
Returning to FIG. 2, the description of the configuration of the autonomous storage apparatus 2 will be continued.

  The access control unit 261d includes content stored in the content storage unit 30 (original content 30a, duplicate content 30b), and index information stored in the index information storage unit 40 (identification information 40a, association information 40b, position Access (reading, writing) to the information 40c) is prohibited (locked) or released. The access control means 261d locks the content and index information with the control information notified from the other autonomous storage device, or conversely notifies the control information to the other autonomous storage device. Lock the contents and index information of the autonomous storage device.

  The cache determination unit 261e determines whether or not content data exists in a cache memory (not shown), and the data hits the cache (exists) or does not hit (does not exist: miss). Judgment is made.

  The content moving unit 262 moves the migration target content (original content 30a) set by the moving content setting unit 261b to another autonomous storage device. This content movement is performed by the content moving means 262 notifying the content operation control means 263 of a content distribution instruction and further notifying a content deletion instruction. In the access distribution unit 27, while access is distributed, access to the content storage unit 30 is reduced, and the access capability of the content storage unit 30 and the network bandwidth of the autonomous storage device 2 are sufficiently secured. Therefore, the content moving unit 262 moves the content during this time. Then, after the content is moved, the access distribution unit 27 is notified that access distribution is to be stopped.

  The content operation control unit 263 operates the content based on various instructions output from the control information analysis unit 261 or the content movement unit 262. The content operation control unit 263 notifies the content storage unit 21 of the content transmission source and the location information (address) stored in the content storage unit 30 based on the content storage instruction, thereby Store (store). Further, the content operation control unit 263 notifies the content distribution unit 22 of the content transmission destination and the location information (address) of the content storage unit 30 based on the content distribution instruction, thereby distributing the content. I do. Further, the content operation control unit 263 deletes the content by notifying the content deletion unit 23 of the location information (address) of the content storage unit 30 based on the content deletion instruction.

  The access distribution unit 27, based on the distribution rate set by the distribution rate setting unit 261c, controls information (access) to the original content 30a stored in the autonomous storage device or the original content stored in the autonomous storage device Among the control information (access) for 30a, the control information for the content to be distributed set by the distribution rate setting means 261c is distributed to other autonomous storage devices storing duplicate content corresponding to the original content 30a. is there. The access distribution unit 27 stops the distribution of access upon receiving a notification from the content moving unit 262 to stop the distribution of access.

Note that the access distribution means 27 restricts the distribution of control information to read access in order to maintain consistency between the original content and the copied content.
As a result, the access distribution means 27 can process the operation on the original content 30a to be distributed as the operation on the replicated content in another autonomous storage device.
When the distribution rate is set by the distribution rate setting unit 261c according to the determination result of the cache determination unit 261e, the access distribution unit 27 preferentially selects another content that does not exist in the cache memory based on the distribution rate. It will be distributed to autonomous storage devices.

  The content storage means 30 stores the original content 30a and a duplicate content 30b that is a duplicate of the original content stored in another autonomous storage device, and is a general storage device such as a hard disk.

  The index information storage means 40 stores index information that is information for specifying the content (original content 30a or duplicate content 30b) stored in the content storage means 30, and is a general storage device such as a hard disk. It is. The index information storage means 40 stores identification information 40a, association information 40b, and position information 40c as index information.

  Here, the identification information 40a is information for uniquely specifying the content, and is, for example, a file name, a number, or the like. The association information 40b is information for associating the content stored in the autonomous storage device 2 with the content stored in another autonomous storage device, and the content stored in the autonomous storage device 2 is the original. In the case of content, the position of the autonomous storage device where the replicated content is stored. In the case where the content stored in the autonomous storage device 2 is the replicated content, the location of the autonomous storage device where the original content is stored. It is information which shows. The position information 40c indicates the address on the content storage means 30 of the content (original content 30a or duplicate content 30b).

By configuring the autonomous storage device 2 in this way, when an access load is concentrated on the autonomous storage device 2, content stored in the autonomous storage device 2 by cooperating with other autonomous storage devices Can be moved to another autonomous storage device, and the access load can be balanced.
At this time, the autonomous storage device 2 moves the content in order to distribute part of the access to the original content stored in the autonomous storage device 2 to the replicated content stored in other autonomous storage devices. Therefore, the access capability of the autonomous storage device and the bandwidth of the network N are ensured. This can prevent a decrease in the throughput of the entire system.

  The system management means 20 of the autonomous storage device 2 can be realized by causing a general computer to execute a program and operating a computing device or a storage device in the computer. The program (load distribution program) for distributing access via the network realized here can be distributed via a communication line, or can be distributed by writing on a recording medium such as a CD-ROM. It is.

Here, as shown in FIG. 1, an autonomous storage system is configured by a plurality of autonomous storage devices 2, but the present invention has the same configuration as the autonomous storage device 2 as shown in FIG. 13. A single storage unit 3 and a plurality of general storage apparatuses 4 may be configured as a distributed storage system 1B connected to the network N.
The controller 3 may be omitted the content storage unit 30 _1.

[Operation of autonomous storage system]
Next, the operation of the autonomous storage system will be described with reference to FIG. 4 (see FIGS. 1 and 2 as appropriate). Here, in the autonomous storage system according to the present invention, an operation in which the autonomous storage apparatus distributes the access load in cooperation with other autonomous storage apparatuses will be described. FIG. 4 is a flowchart showing the load balancing operation in the autonomous storage system according to the present invention.

(Overall operation)
[Load status detection step]
First, the autonomous storage system 1 uses the load state detection means 261a of the content management means 26 in each autonomous storage device 2 (2 ₁ to 2 ₄ ), for example, from the number of accesses to the content per unit time. Is detected, and based on a predetermined threshold value, it is determined whether or not the load state of the autonomous storage device 2 is overload (step S1).
Here, when the load state is not overload (“load ≦ threshold” in step S1), the operation continues with step S1. On the other hand, when the load state is overload (“load> threshold” in step S1), the process proceeds to step S2.

  Then, the autonomous storage apparatus 2 determined to be overloaded further determines whether the migration is necessary by determining whether the load state exceeds a predetermined threshold by the moving content setting unit. Is determined (step S2). If it is determined that migration is not necessary (“No” in step S2), the distribution ratio setting unit 261c sets the access distribution ratio (step S3), and the process returns to step S1.

[Moving content setting step]
On the other hand, if it is determined that the migration is necessary (“Yes” in step S2), the autonomous storage device 2 uses the moving content setting unit 261b based on the load state detected in step S1 to generate a plurality of original contents. The content (migration target content) to be moved to another autonomous storage device is set (determined) from 30a (step S4).
[Distribution rate setting step]
Then, the autonomous storage system 2 by the distribution ratio setting means 261 c, based on the access status to the content stored in the autonomous storage equipment, to set the distribution ratio of the access (step S5).

[Access distribution step]
Then, the autonomous storage device 2 stores the control information for the migration target content (original content 30a) and the duplicate content corresponding to the original content 30a by the access distribution means 27 based on the distribution rate set in step S3. An operation of distributing to other autonomous storage devices (access distribution) is started (step S6).

[Content movement step]
Subsequently, the autonomous storage device 2 executes a migration process for moving the migration target content (original content 30a) to another autonomous storage device by the content moving unit 262 (step S7). The operation of this migration process will be described in detail later.

[Continuation judgment step]
Then, the autonomous storage device 2 further determines whether or not the content to be migrated exists by the content moving unit 262 (step S8). If it exists (“Yes” in step S8), the process returns to step S7 to operate. Continue.
The distribution rate may be reviewed when one migration operation is completed.

[Access distribution stop step]
On the other hand, when there is no migration target content (“none” in step S8), the autonomous storage device 2 ends the access distribution to other autonomous storage devices by the access distribution means 27 (step S9).
By the above operation, the autonomous storage system 1 can distribute the access load to the autonomous storage apparatus to which access is concentrated to other autonomous storage apparatuses.

(Detailed operation of migration process: Part 1)
Next, referring to FIG. 5 (refer to FIGS. 1 and 2 as appropriate), the operation of the migration process, which is the operation of step S7 in FIG. 4, will be described in detail. FIG. 5 is a flowchart showing the detailed operation of the migration process in FIG. Here, in FIG. 1, the autonomous storage device 2 ₂ to the access load is concentrated, it is assumed that the decision to move the migration target contents to the autonomous storage apparatus 2 ₄ (setting) has been made.

[Writing step]
First, autonomous storage devices 2 _2, by moving the contents setting unit 261b, we intend to identify the original content 30a to be migrated in the file name or the like, the access control means 261 d, the partial information for specifying the content of interest ( The shared lock is sequentially applied to the index information) (step S10). Here, the shared lock allows the reference (reading process) to the information from other than the process (here, the migration process) that performs the locking process on information such as index information and content. , Insert, update, delete, etc. (write processing) operations are prohibited locks. Here, it is assumed that the shared lock state is inherited to the content transfer destination or copy destination. Here, the process means a group of a plurality of related processes as one processing unit. These processes can coexist in one autonomous storage apparatus and operate in parallel. A process has a unique identifier in the system, and is distinguished from other processes by the identifier. Also, the process can operate across multiple autonomous storage devices.
Moreover, the autonomous storage devices 2 _2, the access control means 261 d, and share locks the original content 30a to be migrated (step S11).

[Content transfer step]
Then, the autonomous storage devices 2 _2, by the content moving section 262, transfers a copy of the migration target original content 30a in the autonomous storage apparatus 2 ₄ (step S12). Autonomous storage apparatus 2 ₄ which received the original content 30a of the migration subject, replicate in its own content storage unit 30 ₄ of the original content 30a, and stores the original content (step S13).

[Read prohibition step]
Subsequently, the autonomous storage devices 2 _2, the access control means 261 d, exclusively lock the original content 30a and index information to be migrated (step S14). Here, the exclusive lock refers to a lock that prohibits all operations (write processing and read processing) on the information (index information, content) from other than the process. Here, it is assumed that the exclusive lock state is inherited to the content transfer destination or copy destination.

[Index information update step]
Then, the autonomous storage devices 2 _2, the content management unit 26, the index information stored in the index information storage unit 40 (identification information 40a, etc.), and deletes the information of the migration target original content 30a (step S15) . On the other hand, in the autonomous storage apparatus 2 _4, inserts the information of the original content to be migrated to the index information (step S16).

[Prohibition cancellation step]
Then, the autonomous storage devices 2 _2, the access control means 261 d, releasing all shared lock and an exclusive lock you have made to the original content 30a and index information to be migrated (step S17).

[Content deletion step]
Finally, the autonomous storage devices 2 _2, by the content deletion section 23, the original content 30a to be migrated, to remove from the content storage unit 30 (step S18).
By the above operation, the original content 30a migration target, will have been moved to the autonomous storage apparatus 2 _4.

<Specific example of migration operation>
Next, the migration operation in the autonomous storage system described with reference to FIG. 5 will be described with reference to FIG. FIG. 6 is a schematic diagram showing the migration operation of FIG. Here, a state is shown in which the original contents (C1 to C16) and the duplicate contents (C′1 to C′16) are stored in the autonomous storage devices (2 ₁ to 2 ₄ ) constituting the autonomous storage system.
Here, as shown in FIG. 6 (a), concentrated in autonomous storage system 2 ₂ access load, autonomous storage system, to the autonomous storage system 2 ₄ from the autonomous storage devices 2 _2, as a migration target, the original It is assumed that the contents C7 and C8 are determined to be moved.

Then, as shown in FIG. 6B, the autonomous storage system distributes the access based on the access status to the content stored in the autonomous storage device or the autonomous storage device and other autonomous storage devices. set the rate (here, assumed to be 50%), access to distributed autonomous storage system 2 ₃ which stores the copy content C'7 and C'8 corresponding to the original content C7 and C8. Thus, 50% of access to autonomous storage devices 2 _2, will be dispersed in the autonomous storage unit 2 _3.
Thereafter, the autonomous storage system, as shown in FIG. 6 (c), the original content C8 migration target stored in the autonomous storage device 2 ₂ is moved to the autonomous storage apparatus 2 _4.

Subsequently, autonomous storage system, as shown in FIG. 6 (d), the original content C7 of migrated stored in the autonomous storage device 2 ₂ is moved to the autonomous storage apparatus 2 _4. Incidentally, before the move of the original content C7 is already original content C8 is, since it is stored in the autonomous storage apparatus 2 _4, access to the original content C8 will be made to an autonomous storage apparatus 2 _4.
The original content C7 is at the stage stored in the autonomous storage device 2 _4, as shown in FIG. 6 (e), the autonomous storage system, the access which has been concentrated in the autonomous storage devices 2 _2, the autonomous storage devices dispersed in 2 _4, so that the balancing of the access loads is made.

(Detailed operation of migration process: Part 2)
Next, with reference to FIG. 7 (refer to FIGS. 1 and 2 as appropriate), another operation of the migration process that is the operation of step S7 of FIG. 4 will be described in detail. FIG. 7 is a flowchart showing another operation of the migration process in FIG. Here, in FIG. 1, the autonomous storage device 2 ₂ to the access load is concentrated, it is assumed that the decision to move the migration target contents to the autonomous storage system 2 ₃ (setting) has been made.

[Writing step]
First, the autonomous storage device 2 ₂ specifies the original content 30a to be migrated by a file name or the like by the moving content setting unit 261b, and an index that is management information of the content in the autonomous storage device 2 ₂ by the access control unit 261d. Information is shared and locked (step S20).

Then, the autonomous storage devices 2 _2, the access control means 261 d, the autonomous storage system 2 ₃ replicate content corresponding to the original content 30a to be migrated is stored, that the share lock the index information associated with the copied content Notify the control information. By acquiring the control information, the autonomous storage device 2 ₃ is configured to identify the copy content to be migrated in the file name, etc., to share locks the index information (step S21).

Moreover, the autonomous storage devices 2 _2, the access control means 261 d, and share locks the original content 30a to be migrated (step S22), and the autonomous storage unit 2 _3, and notifies the control information indicating that shared lock the copy content . By acquiring the control information, the autonomous storage system 2 ₃ share locks the copy content to be migrated (step S23).

[Content transfer step]
Then, the autonomous storage devices 2 _2, by the content moving section 262, transfers a copy of the migration target original content 30a in the autonomous storage system 2 ₃ (step S24). Autonomous storage system 2 ₃ receiving the original content 30a of the migration subject, replicate in its own content storage unit 30 ₄ of the original content 30a, and stores the original content (step S25).

Moreover, the autonomous storage devices 2 _3, by the content moving section 262, transfers a copy of the migration target copied content to the autonomous storage apparatus 2 ₄ (step S26). Autonomous storage apparatus 2 ₄ which has received the copy content of the migration target, the content storage unit 30 ₄ replicate themselves in the copied content is stored as copy content (step S27).

[Read prohibition step]
Subsequently, the autonomous storage devices 2 _2, the access control means 261 d, exclusively lock the original content 30a and index information to be migrated (step S28).
Then, the autonomous storage apparatus 2 ₂ notifies the autonomous storage apparatus 2 ₃ of the control information indicating that the duplicate content and the index information are exclusively locked by the access control means 261d. By acquiring the control information, the autonomous storage system 2 ₃ exclusive lock the copy content and the index information (step S29).

[Index information update step]
Then, the autonomous storage devices 2 _2, the content management unit 271, the index information stored in the index information storage unit 40 (identification information 40a, etc.), and deletes the information of the original content 30a (step S30).
Moreover, the autonomous storage devices 2 _3, insert the information of the original content to be migrated to the index information (step S31), and deletes the information of the migration target copy content from the index information (step S32). Moreover, the autonomous storage apparatus 2 _4, inserts the information of the migration target copy content to the index information (step S33).

[Prohibition cancellation step]
Then, the autonomous storage devices 2 _2, the access control means 261 d, releasing all shared lock and an exclusive lock you have made to the original content 30a and index information to be migrated (step S34). Also in the autonomous storage devices 2 _3, releasing all shared lock and an exclusive lock (step S35).

[Content deletion step]
Finally, the autonomous storage devices 2 _2, by the content deletion section 23, the original content 30a to be migrated, and deleted from the content storage unit 30 (step S36), in the autonomous storage devices 2 _3, the copy content to be migrated Delete (step S37).
By the above operation, the original content 30a migration target, thus moved to the autonomous storage unit 2 _3.

<Specific example of migration operation>
Next, the migration operation in the autonomous storage system described with reference to FIG. 7 will be described with reference to FIG. FIG. 8 is a schematic diagram showing the migration operation of FIG. Here, a state is shown in which the original contents (C1 to C16) and the duplicate contents (C′1 to C′16) are stored in the autonomous storage devices (2 ₁ to 2 ₄ ) constituting the autonomous storage system.
Here, as shown in FIG. 8 (a), the autonomous storage device 2 ₂ to the access load is concentrated, the autonomous storage system, to the autonomous storage system 2 ₃ from the autonomous storage system 2 _2, the content C7 and C8 Suppose you decide to move.

Then, as shown in FIG. 8B, the autonomous storage system sets the access distribution rate based on the access status to the contents C7 and C8 (here, it is assumed that it is 50%), distributing the autonomous storage system 2 ₃ which stores the copy content C'7 and C'8 corresponding to the original content C7 and C8. Thus, 50% of access to autonomous storage devices 2 _2, will be dispersed in the autonomous storage unit 2 _3.
Thereafter, the autonomous storage system, as shown in FIG. 8 (c), the original content C8 migration target stored in the autonomous storage device 2 ₂ is moved to the autonomous storage system 2 ₃ as original content C8. Further, the copied content C'8 corresponding to the autonomous storage system 2 ₃ original content C8 to be migrated stored in, move the autonomous storage apparatus 2 ₄ as copied content C'8.

Subsequently, autonomous storage system, as shown in FIG. 8 (d), the original content C7 of migrated stored in the autonomous storage device 2 ₂ is moved to the autonomous storage system 2 ₃ as original content C7. Further, the copied content C'7 corresponding to the autonomous storage system 2 ₃ original content C7 of migrated stored in, move the autonomous storage apparatus 2 ₄ as copied content C'7. Incidentally, in FIG. 8 (d), the autonomous storage devices 2 _3, access A1 due to the distributed access described in FIG. 8 (b), the access A2 to the moved content (original content C8) is Will be made.

Then, at the stage where the original content C7 and copy content C'7 migration target is moved, as shown in FIG. 8 (e), the autonomous storage system, the access which has been concentrated in the autonomous storage devices 2 _2, autonomic dispersed in the storage device 2 _3, so that the balancing of the access loads is made.
Note that according to this operation, even after the access load is balanced, the so-called chained clustering structure in which duplicate content corresponding to the original content is stored in the logically adjacent autonomous storage device is not destroyed. Therefore, fault tolerance is maintained.

(Detailed operation of migration processing: Part 3)
Next, with reference to FIG. 9 (refer to FIGS. 1 and 2 as appropriate), another operation of the migration process that is the operation of step S5 of FIG. 4 will be described in detail. FIG. 9 is a flowchart showing another operation of the migration process in FIG. Here, in FIG. 1, the autonomous storage devices 2 ₂ access is concentrated, it is assumed that the decision to move the migration target contents to the autonomous storage system 2 ₃ (setting) has been made.
In FIG. 9, the operation from the step S20 to the step S23 [write prohibition step] is the same as the operation described in FIG.

[Content transfer step]
After step S23, the autonomous storage devices 2 _2, by the content moving section 262, transfers a copy of the migration target original content 30a in the autonomous storage apparatus 2 ₄ (step S24B). The migration autonomous storage apparatus 2 ₄ which received the original content 30a of the subjects, replicate in its own content storage unit 30 ₄ of the original content 30a, and stores the copied content (step S27B).

[Read prohibition step]
Subsequently, the autonomous storage devices 2 _2, the access control means 261 d, exclusively lock the original content 30a and index information to be migrated (step S28).
Then, the autonomous storage apparatus 2 ₂ notifies the autonomous storage apparatus 2 ₃ of the control information indicating that the duplicate content and the index information are exclusively locked by the access control means 261d. By acquiring the control information, the autonomous storage system 2 ₃ exclusive lock the copy content and the index information (step S29).

[Content movement step]
Then, the autonomous storage system 2 ₃ moves the copied content in the region of the original content (step S29b).
The subsequent operations [prohibition release step, content deletion step] are the same as the operations from step S30 to step S36 described in FIG.
By the above operation, the original content 30a migration target, thus moved to the autonomous storage unit 2 _3.

<Specific example of migration operation>
Next, the migration operation in the autonomous storage system described in FIG. 9 will be described with a specific example with reference to FIG. FIG. 10 is a schematic diagram showing the migration operation of FIG. Here, a state is shown in which the original contents (C1 to C16) and the duplicate contents (C′1 to C′16) are stored in the autonomous storage devices (2 ₁ to 2 ₄ ) constituting the autonomous storage system.
10 (a) and 10 (b) show the same operations as those in FIGS. 8 (a) and 8 (b), and a description thereof will be omitted.

In FIG. 10 (b), after the access is distributed autonomous storage devices 2 _3, the autonomous storage system, as shown in FIG. 10 (c), original content to be migrated stored in the autonomous storage system 2 ₂ the C8, is moved to the autonomous storage apparatus 2 ₄ as copied content C'8. Further, the copied content C'8 corresponding to the autonomous storage system 2 ₃ original content C8 to be migrated stored in, move the original content C8 autonomous storage device 2 _3.

Subsequently, autonomous storage system, as shown in FIG. 10 (d), to move the autonomous storage devices 2 ₂ original content C7 of migrated stored in, the autonomous storage apparatus 2 ₄ as copied content C'7 . Further, the copied content C'7 corresponding to the autonomous storage system 2 ₃ original content C7 of migrated stored in, move the original content C7 in the original content area. Incidentally, in FIG. 10 (d), the the autonomous storage devices 2 _3, access A1 due to the distributed access in FIG. 10 (b), the access A2 to the moved content (original content C8) is performed It will be different.

Then, at the stage where the original content C7 and copy content C'7 migration target is moved, as shown in FIG. 10 (e), the autonomous storage system, the access which has been concentrated in the autonomous storage devices 2 _2, autonomic dispersed in the storage device 2 _3, so that the balancing of the access loads is made.
Note that according to this operation, even after the access load is balanced, the so-called chained clustering structure in which duplicate content corresponding to the original content is stored in the logically adjacent autonomous storage device is not destroyed. Therefore, fault tolerance is maintained. Furthermore, according to this operation, when moving the content to be migrated, the number of times of moving the content via the network is reduced compared to the operation described in FIG. Throughput can be improved.

It is a schematic block diagram which shows the structure of the autonomous storage system which concerns on this invention. It is a block diagram which shows the structure of the autonomous storage apparatus which concerns on this invention. It is explanatory drawing for demonstrating the setting method of the content for migration, and the setting method of a distribution rate. It is a flowchart which shows the load distribution operation | movement in the autonomous storage system which concerns on this invention. 5 is a flowchart showing a detailed operation of the migration process in FIG. 4. It is the schematic diagram which showed the migration operation | movement of FIG. 6 is a flowchart showing another operation of the migration process in FIG. FIG. 8 is a schematic diagram illustrating the migration operation of FIG. 7. 6 is a flowchart showing another operation of the migration process in FIG. FIG. 10 is a schematic diagram illustrating the migration operation of FIG. 9. It is a flowchart which shows the load distribution operation | movement in the conventional autonomous storage system. 12 is a flowchart showing a detailed operation of the migration process in FIG. It is the schematic diagram which showed the migration operation | movement in the conventional autonomous storage system. 1 is a schematic block diagram showing a configuration of a distributed storage system according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Autonomous storage system 1B Distributed storage system 2 Autonomous storage apparatus 3 Controller 4 Storage apparatus 10 Communication transmission / reception means 20 System management means 21 Content storage means 22 Content distribution means 23 Content deletion means 24 Control information reception means 25 Control information transmission means 26 Content management Means 261 Control information analysis means 261a Load state detection means 261b Movement content setting means 261c Distribution rate setting means 261d Access control means 261e Cache determination means 262 Content movement means 263 Content operation control means 27 Access distribution means 30 Content storage means 40 Index information storage means

Claims (8)

In an autonomous storage device in an autonomous storage system in which a plurality of autonomous storage devices that store original content and duplicate content that is a copy of the original content stored in another autonomous storage device are connected via a network ,
Content storage means for storing a plurality of original contents stored in the autonomous storage apparatus and duplicate contents corresponding to the original contents stored in another autonomous storage apparatus connected to the network;
Based on the access status to the autonomous storage equipment, a load condition detecting means for detecting the load state,
Based on the load state detected by the load state detection means, the moving content setting means for setting the original content to be moved to another autonomous storage device from the plurality of original contents,
Based on the access status to the original content stored in the autonomous storage equipment, and distribution ratio setting means for setting a distribution ratio of the access,
Based on the distribution rate set by the distribution rate setting means, a part of access to the autonomous storage device is stored as another copy content corresponding to the original content stored in the autonomous storage device. Access distribution means for distributing to the autonomous storage device;
A content moving means for moving the original content set by the moving content setting means to another autonomous storage apparatus after distribution of access is started at the distribution rate in the access distributing means;
An autonomous storage device comprising: A cache memory for predicting and temporarily storing content that is likely to be accessed next;
Cache determining means for determining whether or not the original content data exists in the cache memory,
2. The autonomous storage device according to claim 1, wherein the access distribution unit distributes access to other autonomous storage devices preferentially from the original content that did not exist in the cache memory based on the distribution rate. .   The moving content setting means sets the original content to be moved to another autonomous storage device when a value indicating the load state exceeds a predetermined threshold value. The autonomous storage device described. An autonomous storage system in which a plurality of autonomous storage devices that store original content and replicated content that is a copy of the original content stored in another autonomous storage device are connected via a network,
The autonomous storage device
Content storage means for storing a plurality of original contents stored in the autonomous storage apparatus and duplicate contents corresponding to the original contents stored in another autonomous storage apparatus connected to the network;
Based on the access status to the autonomous storage equipment, a load condition detecting means for detecting the load state,
Based on the load state detected by the load state detection means, the moving content setting means for setting the original content to be moved to another autonomous storage device from the plurality of original contents,
Based on the access status to the original content stored in the autonomous storage equipment, and distribution ratio setting means for setting a distribution ratio of the access,
Based on the distribution rate set by the distribution rate setting means, a part of access to the autonomous storage device is stored as another copy content corresponding to the original content stored in the autonomous storage device. Access distribution means for distributing to the autonomous storage device;
A content moving means for moving the original content set by the moving content setting means to another autonomous storage apparatus after distribution of access is started at the distribution rate in the access distributing means;
An autonomous storage system characterized by comprising: Autonomous storage in an autonomous storage system in which a plurality of autonomous storage devices having content storage means for storing original content and replicated content that is a copy of the original content stored in another autonomous storage device are connected via a network In order to distribute the load on the device, a computer that controls the autonomous storage device
Based on the access status to the autonomous storage equipment, load state detection means for detecting a load state,
Based on the load state detected by the load state detection means, a moving content setting means for setting original content to be moved to another autonomous storage device from the plurality of original contents,
Based on the access status to the original content stored in the autonomous storage equipment, distribution rate setting means for setting a distribution ratio of the access,
Based on the distribution rate set by the distribution rate setting means, a part of access to the autonomous storage device is stored as another copy content corresponding to the original content stored in the autonomous storage device. Access distribution means for distributing to autonomous storage devices;
Content moving means for moving the original content set by the moving content setting means to another autonomous storage device after access distribution is started at the distribution rate in the access distributing means,
A load balancing program characterized by functioning as In an autonomous storage system in which a plurality of autonomous storage apparatuses that store original contents and duplicate contents that are duplicates of original contents stored in other autonomous storage apparatuses are connected via a network , load distribution among the autonomous storage apparatuses A load balancing method for performing
Based on the access status to the autonomous storage equipment, a load state detection step of detecting a load state,
Based on the load state detected in this load state detection step, a moving content setting step for setting original content to be moved to another autonomous storage device from among the plurality of original contents;
Based on the access status to the autonomous storage equipment to the stored original content, and distribution ratio setting step of setting the distribution ratio of the access,
Based on the distribution rate set in the distribution rate setting step, another part of the copy content corresponding to the original content stored in the autonomous storage device is stored as a part of access to the autonomous storage device An access distribution step for distributing to the autonomous storage device;
A content moving step of moving the original content set in the moving content setting step to another autonomous storage device after distribution of access is started at the distribution rate in the access distributing step;
The load distribution method characterized by including. Distributed storage in which a plurality of storage devices that store original content and copied content that is a copy of the original content stored in another storage device and a controller that controls the plurality of storage devices are connected via a network A system,
The controller is
Based on the access status to the storage equipment, to detect the load state of the storage device, or a load state detection means for obtaining a detected load condition in said storage device,
Based on the load state detected by the load state detection means, a moving content setting means for setting original content to be moved to another storage device from among the plurality of original contents,
A distribution rate setting means for setting a distribution rate for distributing access from the storage device to another storage device that moves the original content, based on the access status to the original content stored in the storage device;
Based on the distribution ratio set by the distribution ratio setting means, another storage apparatus that stores a part of access to the storage apparatus and a duplicate content corresponding to the original content stored in the storage apparatus Access distribution means for distributing to
A content moving means for moving the original content set by the moving content setting means to another storage device after distribution of access is started at the distribution rate in the access distributing means;
A distributed storage system characterized by comprising:   The said controller is provided with the content memory | storage means to memorize | store the said original content and the replication content corresponding to the original content memorize | stored in the other storage apparatus connected to the said network. The described distributed storage system.

Images