JP2007249603A - Data storage method and virtual storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive virtual storage device substantially having no upper limit for storage capacity. <P>SOLUTION: The virtual storage device 10 which receives a writing request from a transmitting source host transmits an echo request containing storage data to at least one of transmitting destination hosts 21-2n connected to the Internet 2. The transmitting destination host which received the echo request returns an echo response containing the storage data. The virtual storage device 10 transmits, upon receipt of the echo response, the echo request containing the storage data again. The echo requesting and the echo responding are repeated thereafter, whereby the storage data is reciprocated on communication lines between the transmitting source host and the transmitting destination hosts and retained for a long time on the Internet. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a data storage method and a virtual storage device, and more particularly to a data storage method and a virtual storage device that use the Internet as a storage medium.

  In recent years, the demand for a thin client system having a diskless client (terminal) is increasing for the purpose of reducing management costs and security measures. However, an existing thin client system requires a server having a large-scale storage device remotely simply because the client does not have a local hard disk. For this reason, a large amount of capital investment is required to introduce a thin client system.

  Further, the storage device provided in the server has an upper limit on the storage capacity. Therefore, if the amount of data to be stored exceeds the storage capacity, it is necessary to add a storage device or replace it with a storage device with a larger storage capacity. Data migration to a new storage device is also required. Therefore, extra cost and labor are required for the maintenance.

  As described above, the conventional thin client system requires a large amount of money and labor for installation and maintenance.

  As described above, the conventional thin client system requires a large amount of cost and labor for its installation and maintenance, but much of the cost and labor is for the storage apparatus. That is, in the conventional thin client system, in order to store a large amount of data, it is necessary to prepare a storage device including a physical storage medium such as a magnetic disk, and there is an upper limit on the storage capacity.

  Accordingly, an object of the present invention is to provide a data storage method and a virtual storage device that can reduce the cost related to the storage device and can store a large amount of data without any upper limit.

  According to a first aspect of the present invention, in the data storage method, an echo request including stored data is transmitted to a host connected to an IP network, and if there is an echo response including the stored data from the host, the data is stored again. , By repeating the operation of transmitting an echo request including the stored data to the host, and keeping the stored data on the network, thereby using the network as a virtual storage device for storing the stored data. It is characterized by doing. Data storage method.

  The second gist of the present invention is that, in a virtual storage device, stored data for a host connected between a computer and an IP network and connected to the IP network in response to a write request from the computer. When an echo response including the stored data is received from the host, the operation of transmitting the echo request including the stored data to the host is repeated.

  Specifically, the virtual storage device includes a transmission destination table that stores information about a host that can be a transmission destination of the stored data, a transmission destination monitoring unit that updates the transmission destination table, the storage data, and transmission thereof A storage data table for storing information indicating the relationship with the previous host, and control of data transmission / reception with the IP network using the transmission destination table and the storage data table in response to a request from the computer A transmission / reception control unit.

  Furthermore, a third aspect of the present invention is to use the IP network as a storage medium in a data storage method by continuing to make data exist on the IP network using an echo request and an echo response defined in RFC792. It is characterized by that.

  The first effect is that data can be stored without providing a physical storage medium.

  The reason is to use resources on the Internet as a storage medium.

  The second effect is that there is substantially no upper limit on storage capacity.

  The reason is that a virtually inexhaustible resource on the Internet is used as a storage medium.

  The third effect is that the present invention can be implemented without modifying the host of the communication partner on the Internet, and thus the cost can be suppressed.

  This is because the present invention can be realized by using an ICMP echo request and echo response defined in RFC 792 as an Internet communication protocol.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  First, an overview of a virtual storage apparatus according to an embodiment of the present invention will be described with reference to FIG.

  The virtual storage device 10 according to the present embodiment uses the Internet 2 as a storage device of the transmission source host 1. That is, the virtual storage device 10 uses the communication path of the Internet 2 as a storage medium instead of a physical storage medium.

  A large number of destination hosts 21, 22,..., And 2n are connected to the Internet 2. In order to transmit / receive data between the destination hosts 21 to 2n and the source host 1 also connected to the Internet 2 via a number of routers 211 to 21o, 221 to 22p, and 2n1 to 2nq. Can be formed. The virtual storage device 10 does not have a storage medium for storing a large amount of data such as a hard disk, as will be described later, the destination hosts 21 to 2n, the route to each host, and the router on the route A buffer area (not shown) of 211 to 2nq is used as a storage medium for storing data.

  The virtual storage apparatus 10 that has received the write request from the transmission host 1 transmits the storage data d1, d2,..., And d6 to the transmission destination hosts 21 to 2n via the Internet. Data transmitted on the Internet 2 is relayed while being buffered (temporarily stored) in a plurality of routers 211 to 2nq on the route, and reaches the destination hosts 21 to 2n. Here, if the data received by the transmission destination hosts 21 to 2n is sent back to the transmission source host 1 as it is, and the storage data d1 to d6 sent back by the transmission source host 1 is retransmitted as it is, the stored data is repeated. d1 to d6 are held for a long time while reciprocating on the communication path of the Internet 2.

  As described above, the virtual storage device 10 according to the present embodiment uses the Internet as a storage medium by keeping data on the Internet.

  In the virtual storage apparatus 10 according to the present embodiment, the apparent storage capacity per communication path can be increased by transmitting a plurality of stored data to the same destination host in a multiplexed manner (for example, transmission Storage data d1 to d3 addressed to the destination host 21).

  Further, by transmitting a plurality of stored data to a plurality of destination hosts, the data can exist on different communication paths, and the overall apparent storage capacity can be increased (for example, the destination) Storage data d1 to d3 addressed to the host 21 and storage data d4 to d6 addressed to the destination host 22).

  Further, by duplicating the same stored data and simultaneously transmitting it to a plurality of destination hosts, it is possible to improve reliability by redundancy (stored data d1 to d3 addressed to the destination hosts 21 and 2n).

  The virtual storage apparatus 10 only needs to have a small storage area such as a management information or a buffer for temporarily storing data in order to realize the above-described operation, and has a large capacity necessary for storing all the data. Does not require storage media.

  Further, since the above operation can be realized using a general protocol used on the Internet 2, it is not necessary to modify the destination hosts 21 to 2n.

  Next, the virtual storage device 10 will be described in more detail with reference to FIG.

  As shown in FIG. 2, the transmission source host 1 includes a computer 11, a virtual storage unit 12, and a transfer unit 13. The virtual storage unit 12 and the transfer unit 13 correspond to the virtual storage device 10 of FIG.

  The computer 11 operates by regarding the virtual storage unit 12 as a storage device. There are three types of access requests from the computer 11 to the virtual storage unit 12: a data write request (data storage request), a stored data read request, and a stored data deletion request.

  The virtual storage unit 12 includes a transmission / reception control unit 121, a transmission destination monitoring unit 122, a transmission / reception buffer 123, a stored data table 124, a transmission destination table 125, and a table data operation unit 126.

  The transmission / reception control unit 121 functions as a storage access window from the computer 11 to the virtual storage unit 12. When a write request is received from the computer 11, the stored data is newly transmitted to one or more transmission destinations. On the other hand, when a read request is received from the computer 11, it waits until the desired stored data is received, and returns it to the computer 11 after the reception. In addition, the transmission / reception control unit 121 keeps the stored data always activated on the Internet 2 by repeating exchange (transmission / reception) of the storage data with the transmission destination. Furthermore, the transmission / reception control unit 121 uses the storage data table 124 and the transmission destination table 125 to acquire the IP addresses of the transmission destination hosts 21 to 2n, add or delete storage data, and determine whether data loss has occurred. Judgment and recovery processing in case of data loss.

  The transmission destination monitoring unit 122 periodically monitors the transmission destination table 125 and manages the communication state of each of the transmission destination hosts 21 to 2n. In the regular monitoring, a process for invalidating a destination host whose response time has timed out and a process for re-enabling a destination host for which a certain time has elapsed since the invalidation for reuse are performed.

  The transmission / reception buffer 123 is a storage area for temporarily storing a set of one or more stored data and a stored data identifier.

  The stored data table 124 and the transmission destination table 125 will be described later.

  The table data operation unit 126 implements a data operation processing means using a structured query language (SQL) in order to facilitate the aggregation and editing of the stored data table 124 and the transmission destination table 125.

  The transfer unit 13 has a function of transmitting an ICMP echo request (ICMP Echo Request) defined by RFC 792 and receiving the echo response (ICMP Echo Reply). The transfer unit 13 uses the contents of the transmission / reception buffer 123 as a payload of an echo request during transmission, and stores the payload of an echo response in the transmission / reception buffer 123 during reception.

  It is assumed that destination hosts 21 to 2n exist on the Internet 2 as communication partners of the source host 1. Each of the destination hosts 21 to 2n has a function of receiving an echo request from the source host 1 and returning a corresponding echo response.

  Next, the storage data table 124 and the transmission destination table 125 will be described with reference to FIG.

  FIG. 3 is a diagram illustrating schemas of the storage data table 124 and the transmission destination table 125. In FIG. 3, underlined characters represent primary keys, and italicized characters represent foreign keys.

  The storage data table 124 is a storage area that holds information indicating which storage data is currently exchanged with which destination host. In the stored data table 124, a stored data identifier 1241 and an IP address are stored in association with each other. The stored data table 124 has zero rows in the initial state.

  The stored data identifier 1241 is an identifier that uniquely identifies currently stored data. The IP address 1242 is the IP address of the destination host of the stored data of the corresponding stored data identifier 1241.

  The members of the stored data table are also included in the actual ICMP packet. Specifically, the stored data identifier 1241 is included in the payload of the echo request or echo response, and the IP address 1242 is included in the IP header.

  The transmission destination table 125 is a storage area for managing a list of IP addresses of transmission destination hosts that can be all transmission destinations based on the communication state. In the transmission destination table 125, an IP address 1251, a valid flag 1252, and a time stamp are stored in association with each other.

  The IP address 1251 is an IP address of a host on the Internet 2 that can be a destination host.

  The valid flag 1252 is a logical value indicating whether or not the corresponding IP address 1251 is currently valid. When the valid flag 1252 is true, the corresponding IP address 1251 is a candidate for selecting a destination host, and conversely, when it is false, it is excluded from the candidates for the destination host. In the initial state, the validity flag 1252 is valid for all IP addresses registered in the transmission destination table 125.

  The time stamp 1253 has a different meaning depending on the value of the validity flag 1252. That is, when the valid flag 1252 is true, the time stamp 1253 stores the time when the stored data was last transmitted to the host of the corresponding IP address 1251. However, if the stored data has not yet been transmitted after the IP address becomes valid, the time stamp 1253 stores an initial value (for example, a special minimum time such as zero). On the other hand, when the validity flag 1252 is false, the time stamp 1253 stores the time when the validity flag 1252 transits to false.

  Next, the operation of the virtual storage apparatus of FIG. 2 will be described with reference to the flowcharts of FIGS. In the following description, the following constants and variables are used. The visible range of these constants and variables is the entire embodiment.

  “Number of parallel transmissions”: A constant indicating how many hosts of the stored data should be expanded in parallel for redundancy. The greater the number of parallel transmissions, the more redundant the stored data.

  “Reception timeout”: A constant indicating the maximum waiting time from when the stored data is transmitted until the reply is received.

  “Reuse waiting time”: a constant indicating the waiting time until a destination host once invalidated is reused as a candidate for a destination host.

  “Read wait identifier”: a variable that holds a stored data identifier that is a target of a data read request. However, when there is no read request, a special value (in this case, null) is stored.

  4 to 8 are flowcharts for explaining the operation of the transmission / reception control unit 121. FIG. 4 is a main loop, and FIGS. 5 to 8 are routines corresponding to steps A9 to A11 in FIG. . FIG. 9 is a flowchart for explaining the operation of the transmission destination monitoring unit 122.

  As shown in FIG. 4, the transmission / reception control unit 121 waits for an event after being initialized (step A1). (Step A2). If an event occurs, the transmission / reception control unit 121 determines the type of the event (step A3), and repeats the operation of performing processing according to the type of event.

  Events that occur include a write request (step A4), a read request (step A5), a delete request (step A6), and a stored data reception (step A7).

  Three requests, a write request, a read request, and a delete request, are events that are triggered by a storage access request from the computer 11. On the other hand, the storage data reception is an event that is triggered by a storage data reception notification from the transfer unit 13.

  After receiving each event, the transmission / reception control unit 121 calls and executes a procedure for performing a corresponding process (steps A8, A9, A10, A11).

  When the event is a write request or storage data reception, the transmission / reception control unit 121 performs processing corresponding to each event, performs error determination (steps A12 and A13), and subsequently notifies the computer 11 of the result ( Steps 14, 15 and 17) are performed. If the event is a deletion request, a result notification (step 17) to the computer 11 is performed. When the event is a read request, neither error determination nor result notification is performed (result notification is performed in the procedure of FIG. 8 executed when desired storage-data is received later).

  Next, a procedure for processing a write request will be described with reference to FIG.

  The write request includes a case of newly storing stored data and a case of performing a retransmission process of a copy of stored data that has already been stored. First, the transmission / reception control unit 121 determines whether the write request is a new write request or for replenishing the shortage of the parallel transmission number (step B1).

  In the case of a new write request, since new storage data is transferred from the computer 11 to the transmission / reception control unit 121, a storage data identifier for the storage data is generated (step B2). On the other hand, if it is for supplementing the shortage of the number of parallel transmissions, the stored data identifier already exists, so step B2 is omitted.

  Next, the transmission / reception control unit 121 acquires, from the transmission destination table 125, rows in which the validity flag 1252 is true in order from the smallest time stamp 1253. As a result, IP addresses that have not been used recently are sequentially acquired from the list of IP addresses that are currently valid as transmission destination candidates (step B3).

  Next, the transmission / reception control unit 121 determines whether the sum of the acquired number of IP addresses and the number of stored data replicas currently being exchanged is equal to or greater than the number of parallel transmissions (step B4).

  If the determination result in step B4 is false, it is not possible to develop a copy of the stored data that satisfies the number of parallel transmissions, so it is determined that the expected redundancy cannot be ensured, and the procedure ends in a failed state (step B10). .

  On the other hand, if the determination result in step B4 is true, the stored data identifier and stored data are transmitted according to the order of the IP addresses obtained in step B3 until the number of stored data replicas reaches the number of parallel transmissions (step B5). (Step B6), a row corresponding to the stored data transmitted to the stored data table 124 is added (Step B7), and the time stamp 1253 associated with the IP address of the transmission destination host in the transmission destination table 125 is further displayed at the current time. The updating operation (step B8) is repeated.

  If it is determined in step B5 that all copies of stored data have been transmitted, the procedure ends in a successful state (step B9).

  Next, a procedure for processing a read request will be described with reference to FIG.

  When there is a read request, the transmission / reception control unit 121 stores the storage data identifier to be read in the read waiting identifier (step C1), and ends the procedure in a successful state (step C2).

  Next, a procedure for processing a deletion request will be described with reference to FIG.

  When there is a deletion request, the transmission / reception control unit 121 deletes all rows having the storage data identifier to be deleted from the storage data table 124 (step D1), and ends the procedure in a successful state (step D2).

  Next, the procedure when the stored data is received will be described with reference to FIG.

  First, the transmission / reception control unit 121 searches the storage data table 124 for a row having the storage data identifier of the received storage data and the IP address of the transmission source of the storage data (step E1).

  If no corresponding row is found in the stored data table 124 (No in step E2), either the IP address has been invalidated due to a reception timeout or the stored data has been deleted due to a deletion request. Then, the procedure is terminated in a successful state without performing retransmission (step E12).

  On the other hand, when a row corresponding to the stored data table 124 is found (Yes in step E2), the stored data is retransmitted to the destination host of the IP address (step E3), and the IP address is stored in the destination table 125. The time stamp 1253 associated with the address is updated with the current time (step E4).

  Next, the transmission / reception control unit 121 refers to the read wait identifier to determine whether or not it is currently in a read wait state (step E5). When in the read waiting state (Yes in step E5), the computer 11 is notified of the read result (step E6), and null is stored in the read wait identifier to reset the read waiting state (step E7).

  Next, the transmission / reception control unit 121 counts the number of rows having the same storage data identifier as the storage data identifier of the received storage data from the storage data table 124, so that the number of transmission destinations of the storage data at present is It is checked whether it is exchanged with the host (step E8). Subsequently, the transmission / reception control unit 121 determines whether or not the number of stored data being exchanged at present is less than the number of parallel transmissions (step E9).

  If it is determined in step E9 that the number of stored data replicas currently being exchanged is equal to the number of parallel transmissions, it is determined that the expected redundancy has been secured, and the procedure is terminated in a successful state ( Step E12).

  On the other hand, if it is determined in step E9 that the number of replicas is less than the number of parallel transmissions, it is necessary to re-secure the redundancy, so the procedure shown in FIG. 5 is executed to supplement the shortage (step E10). ). Then, the transmission / reception control unit 121 determines the end state of the procedure of FIG. 5 (step E11), and ends this procedure in a success state or a failure state according to the determination result (steps E12, E13).

  Next, the operation of the transmission destination monitoring unit 122 will be described with reference to FIG.

  As illustrated in FIG. 9, the transmission destination monitoring unit 122 repeatedly executes Step F1 to Step F4.

  More specifically, the transmission destination monitoring unit 122 first waits until a certain time elapses (step F1).

  Next, in order to temporarily disable the IP address with a slow response time, the transmission destination monitoring unit 122 sets the valid flag 1252 of the transmission destination table 125 to true and the time stamp 1253 is not zero for all rows. It is checked whether the difference between the current time and the time stamp 1253 exceeds the reception timeout. For the line exceeding the reception timeout, the validity flag 1252 is set to false, and the time stamp 1253 is set to the current time (step F2).

  Next, in order to reliably interrupt the communication with the IP address that has undergone reception timeout, the transmission destination monitoring unit 122 sets the IP address of those lines for all the lines for which the validity flag 1252 of the transmission destination table 125 is false. The row having the same IP address 1242 as 1251 is deleted from the stored data table 124 (step F3).

  Next, in order to reuse the IP address that has been temporarily unavailable in the past, the transmission destination monitoring unit 122 sets the current time and time for all rows in which the validity flag 1252 of the transmission destination table 125 is false. It is checked whether the difference between the stamps 1253 exceeds the reuse waiting time. For the line exceeding the reuse waiting time, the valid flag 1252 is set to true, and the time stamp 1253 is set to zero (step F4).

  As described above, the virtual storage device according to the present embodiment uses the Internet 2 as a storage medium. There are already countless hosts and routers on the Internet, and they are still increasing. For this reason, it can be said that the Internet communication path is inexhaustible as a data storage area, and can be regarded as a storage device with no upper limit on storage capacity.

  Thus, according to the present embodiment, it is possible to provide a large capacity virtual disk at low cost to a diskless computer.

  While the present invention has been described with reference to one embodiment, the present invention is not limited to the above embodiment.

  For example, in the above embodiment, a list of fixed IP addresses is stored in the destination table 125 of FIG. 2, but instead the destination table 125 is automatically expanded by automatically discovering IP addresses. However, the storage capacity may be increased dynamically. This can be realized, for example, by adding a function to automatically circulate the WWW like a search engine and automatically discovering the IP address of the WEB server. Further, it is possible to automatically discover the IP address of the host by using a technique generally called “PING Scan” or “PING Sweeps”.

  In the above embodiment, the route information reaching the destination hosts 21 to 2n is not managed, but the route information may also be managed in order to make the stored data more redundant or load-balanced. . The route information can be acquired in the category of ICMP as in the case of stored data, for example, by using a technique called a traceroute.

  In addition, when there are a plurality of transmission source hosts 1 in FIG. 2, the stored data can be transferred between these hosts. For example, when the transfer source host sends an echo request (ICMP Echo Request), if the source IP address is disguised as the IP address of the transfer destination host, the corresponding echo reply (ICMP Echo Reply) is sent from the transfer source host. It does not reach the host, but instead reaches the destination host. Here, when the transfer destination host receives an echo response (ICMP Echo Reply), if the received event is handled in the same manner as the write request event from the computer 11, the transferred data is stored data of the own host thereafter. Will be treated as.

  Furthermore, although the case where the Internet is used has been described in the above embodiment, any network (IP network) configured to return an echo response to an echo request may be used. For example, the present invention is applied to an intranet. If the data storage area is closed to the network in the organization, security can be improved.

It is a figure for demonstrating the outline | summary of the virtual storage apparatus which concerns on one embodiment of this invention. FIG. 2 is a block diagram showing a configuration of a virtual storage device in FIG. 1. FIG. 3 is a diagram illustrating a schema of a storage data table and a transmission destination table included in the virtual storage apparatus of FIG. FIG. 3 is a flowchart for explaining the operation of a transmission / reception control unit included in the virtual storage apparatus of FIG. 2, and shows a main loop. It is a flowchart which shows the detail of step A8 included in the flowchart of FIG. It is a flowchart which shows the detail of step A9 contained in the flowchart of FIG. It is a flowchart which shows the detail of step A10 contained in the flowchart of FIG. It is a flowchart which shows the detail of step A11 contained in the flowchart of FIG. 3 is a flowchart for explaining an operation of a transmission destination monitoring unit included in the virtual storage device of FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Source host 10 Virtual storage apparatus 11 Computer 12 Virtual storage part 121 Transmission / reception control part 122 Transmission destination monitoring part 123 Transmission / reception buffer 124 Stored data table 125 Transmission destination table 126 Table data operation part 13 Transfer part 2 Internet 21-2n Destination host 211 to 21o, 221 to 22p, 2n1 to 2nq router

Claims (8)

  An echo request including stored data is transmitted to a host connected to the IP network, and if an echo response including the stored data is received from the host, an echo request including the stored data is transmitted to the host again. The data storage method is characterized in that the network is used as a virtual storage device for storing the stored data by repeating the above operation and keeping the stored data on the network.   The data storage method according to claim 1, wherein redundancy is provided by transmitting the stored data to a plurality of hosts connected to the IP network.   The data storage method according to claim 1 or 2, wherein the echo request and the echo response are an echo request and an echo response defined in RFC792. Connected between the computer and the IP network,
In response to a write request from the computer, an echo request including stored data is transmitted to a host connected to the IP network, and if there is an echo response including the stored data from the host, the storage is performed again. A virtual storage apparatus characterized by repeatedly performing an operation of transmitting an echo request including data to the host. The virtual storage device is
A destination table for storing information about a host that can be a destination of the stored data;
A destination monitoring unit for updating the destination table;
A storage data table for storing information indicating the relationship between the storage data and the host that is the transmission destination;
In response to a request from the computer, a transmission / reception control unit that controls transmission / reception of data with the IP network using the transmission destination table and the stored data table;
The virtual storage apparatus according to claim 4, comprising:   6. The virtual storage apparatus according to claim 4, wherein the transmission / reception control unit transmits the same stored data to a plurality of hosts.   5. A transfer unit that is connected between the transmission / reception control unit and the IP network and transfers data transmitted / received between them as an echo request and an echo response defined in RFC 792. The virtual storage device according to 5 or 6. A data storage method characterized by using the IP network as a storage medium by allowing data to continue to exist on the IP network using an echo request and an echo response defined in RFC792.

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