JPH08297645A - Loose coupling system - Google Patents

Abstract

PURPOSE: To surely decide a substitutive computer by temporarily stopping updating stored contents showing the state of connection or disconnection of faulty host computers to respective loose coupling systems when fault is generated at host computers. CONSTITUTION: When fault is generated at a first host 1, first of all, a fault detection processing means 56 that detects the fault at the first host 1 reports the generation fo fault to a substitutive host deciding means 57 and a connection detection processing means 54 and a disconnection detection processing means 55 instruct a host state control table 52 to lock data of each host so as not to change the data of the host state control table 52. Then, the host state control table 52 locks the stored data so as not to be changed according to the intstruction of the fault detection processing means 56. In this case, a third host 3 as a second candidate connected on the host state control table 52 is decided as the substitutive host of the first host 1. After the substitutive host is decided, a substitutive host deciding means 57 instructs the table 52 to release the lock of data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loosely coupled system having a plurality of host computers and an inter-host shared resource shared by the respective host computers.

[0002]

2. Description of the Related Art In a loosely coupled system composed of a plurality of host computers (hereinafter referred to as "hosts") and shared resources between hosts such as shared files commonly used by the respective hosts, each host is connected by a communication line. Are connected to each other, and each host is configured so that the occurrence of a failure of another host, the connection to the loosely coupled system, and the disconnection from the loosely coupled system are known.

FIG. 2 is a block diagram showing the configuration of a conventional loosely coupled system. FIG. 2 shows an example in which the loosely coupled system is configured by the first host 100, the second host 200, the third host 300, and the inter-host shared resource 400.

In FIG. 2, each host includes inter-host communication means 101, 201 for communicating with other hosts.
301, host status management tables 103, 203 and 303 for managing the statuses of all hosts, alternative host definition tables 104, 204 and 304 that define the relationship between the failed host and its alternative host, and the host Loosely coupled system control means 102 for performing communication with shared resources between hosts, updating the host status management table, and determining an alternative host computer,
202 and 302 are provided, respectively. In such a configuration, when the loosely-coupled system control means 102, 202, 302 provided in each host detect the connection of another host to the loosely-coupled system, the loosely-coupled system control means 103, 203, 303 of the respective host state management tables 103, 203, 303 are detected. When the data indicating the status of the corresponding host is updated to "connect" and the disconnection of the other host from the loosely coupled system is detected, the data of the corresponding host in the respective host status management tables 103, 203, 303 is "disconnected". Was updated to.

Further, when a failure of another host is detected by a watchdog timer or the like for monitoring the operating status, each host status management table 103, 203, 3
The alternative host is determined by searching the alternative host from the hosts that are "connected" in the data of 03. The alternative host is determined by the alternative host definition table 1 shown in Table 1.
The host determined to be the alternative host by referring to 04, 204, and 304 was performing the recovery of the process executed by the failed host.

[0006] In the recovery processing of the alternate host, for example, a failure occurs in the host that was performing processing using the inter-host shared resource 400, and that host cannot use a part of the memory area of the inter-host shared resource 400. There is a process of unlocking so that the locked memory area can be used by another host when the system is stopped in a different locked state.

Table 1 shows an example of the contents of the alternative host definition table. When a failure occurs in the first host, the second host is the first candidate for the alternative host and the third host is the alternative host. It is shown that it will be the second candidate of. Similarly, the second
The alternate host of the host and the alternate host of the third host are defined.

[0008]

[Table 1]

[0009]

However, in the conventional loosely coupled system as described above, the alternate host definition table is provided for each host to determine the alternate host. Therefore, there is a conflict between the alternate host definition tables of each host. Therefore, a plurality of alternative hosts may be determined at the same time, or an unauthorized operation such as the alternative host not being determined may occur.

Even if there is no contradiction between the alternative host definition tables, the alternative host may not be determined at the timing of connection, disconnection, or failure of each host.

As such an example, as shown in the state transition diagram of each host in FIG. 3, the first host and the third host are connected to the loosely coupled system, and the second host is disconnected. Consider a case where the first host fails and is disconnected from the loosely coupled system from the state, and the second host is connected to the loosely coupled system immediately after the failure of the first host.

In this case, since the second host is connected to the loosely coupled system after the occurrence of the failure of the first host, the failure of the first host cannot be detected and the determination processing of the alternative host of the first host is not performed. .

Further, as shown in FIG. 3, since it may take time to detect a failure, the third host executes the "connect" processing of the second host and then the first host fails. May be detected.

Here, if the contents of the alternate host definition table are as shown in Table 1 shown in the conventional example, the second host is "connected" on the host status management table, so the third host Host determines that the second host is the alternate host and does not recognize itself as the alternate host.

Therefore, as described above, no host performs processing as an alternative host of the first host, and
There was a risk that the recovery processing of the host could not be executed. The present invention has been made to solve the problems of the above-described conventional techniques, and an object of the present invention is to provide a loosely coupled system that surely determines an alternative host when a failure occurs in the host. And

[0016]

In order to achieve the above object, a loosely coupled system of the present invention is a loosely coupled system having a plurality of host computers and an inter-host shared resource commonly used by them. The connection or disconnection state of a plurality of host computers to the loosely coupled system is stored for each, and when a failure occurs in any of the host computers in the connection state, the stored contents of the state of each of the plurality of host computers Of the host computer in the connected state to determine the alternative host computer to stop the update of the host computer and recover the interrupted processing of the failed host computer, notify the host computer, and determine the alternative host computer. After that, the stored contents of the state of each of the plurality of host computers A multi-host control device communication unit that has a multi-host control device to be updated, and controls the communication with the multi-host control device for each of the host computers, and the control of communication between the multi-host computers. , And a loosely coupled system control means for controlling communication with the shared resource between hosts.

At this time, the multi-host control device stores host communication means for controlling communication with a plurality of host computers, and data on a state of connection or disconnection of the plurality of host computers to a loosely coupled system. A host state management table, an alternate host definition table that stores candidate alternate host computers for recovering the interrupted processing of the failed host computer for each of the plurality of host computers, and a connection between the host computer and the loosely coupled system are provided. When detected, a connection detection time processing means for updating the data of the host computer in the host state management table to a connection, and when a disconnection of the host computer from the loosely coupled system is detected, the host state management table Disconnection detection for updating the data of the host computer to disconnection Failure detection processing means for instructing to stop updating the host status management table and notifying the occurrence of a failure in the host computer when the occurrence of a failure is detected from either the processing means or the host computer in the connected state According to the failure occurrence notification from the failure detection processing means, the alternative host computer is determined from the connected host computers based on the contents of the alternative host definition table, and the selected host computer is assigned to the alternative host computer. And an alternative host determining means for instructing to release the suspension of updating of the host status management table.

[0018]

In the loosely coupled system of the present invention configured as described above, the multiple host control unit stores the connection or disconnection state of a plurality of host computers to or from the loosely coupled system and connects the loosely coupled system. If any of the host computers that are running fails, the update of the stored contents of each host computer is stopped, and the host computer that failed is selected from the host computers connected to the loosely coupled system. Determine an alternative host computer to recover the interrupted processing of
After determining the alternative host computer, the stored contents of the respective states of each host computer are updated.

As a result, when a failure occurs in the host computer, the update of the stored contents of the connection or disconnection state of each of the plurality of host computers to the loosely coupled system is temporarily stopped. The substitute host computer is reliably determined without depending on the timing of connection, disconnection, or failure occurrence.

[0020]

Next, an embodiment of the present invention will be described with reference to the drawings.

In this embodiment, a case where a loosely coupled system is composed of three hosts will be described as an example.

FIG. 1 is a block diagram showing the configuration of the loosely coupled system of the present invention. In FIG. 1, the loosely-coupled system of the present exemplary embodiment includes a loosely-coupled system including a first host 1, a second host 2, a third host 3, and an inter-host shared resource 4 in which the status of each host is collectively set. The configuration is such that a multiple host control device 5 is added for managing and managing a substitute host when a failure occurs. Then, each host is controlled by the multiple host controller communication means 12, 22, 32 for communicating with the multiple host controller 5, communication between the hosts, and communication with the inter-host shared resource 4. The loosely coupled system control means 11, 21, and 31 for performing the loose coupling system are provided.

The inter-host shared resource 4 is used by being connected to each host after each host is respectively connected to the plural host control device 5 by the loosely coupled system control means 11, 21, 31.

The multi-host control unit 5 has an alternative host definition table 51 in which the relationship between a failed host and an alternative host is stored, and the status of "connection" or "disconnection" between each host and the loosely coupled system. The host status management table 52 stored therein, the host communication means 53 for controlling communication with each host, the connection detection time processing means 54 for processing when the host is connected to the loosely coupled system, and the host sparsely Disconnection detection time processing means 55 that performs processing when disconnected from the coupling system, failure detection time processing means 56 that performs processing when a host fails, and alternate host that determines replacement of the failed host It is constituted by the determining means 57.

The alternative host definition table 51 is a table in which the relationship between the failed host and the alternative host is defined, and is used to determine the alternative host when a failure occurs in the host. The host status management table 52 is a table for managing the status of each host, and stores either one of the two statuses of "connection" and "disconnection" between each host and the loosely coupled system.

The host communication means 53 is a circuit for controlling communication between the multiple host control device 5 and each host.

Further, the connection detection time processing means 54 "connects" the data of the corresponding host in the host status management table 52 by the connection notification from the host connected to the loosely coupled system.
And the disconnection detection time processing unit 55 updates the data of the corresponding host in the host status management table 52 to “disconnected” in response to a disconnection notification from the host disconnecting from the loosely coupled system.

The failure detection processing means 56 monitors the operating status of each host that is "connected" in the host status management table 52 by a watchdog timer or the like, and substitutes when an abnormality (failure) occurs in the host. Host determination means 5
Notify 7 of the occurrence of the failure.

The alternative host determining means 57 determines an alternative host based on the contents of the alternative host definition table 51 and the host status management table 52 according to the failure occurrence notification from the failure detection processing means 56, and the determined alternative host. To the recovery processing of the failed host.

Next, the operation of the loosely coupled system of this embodiment in the case of fault processing in such a configuration will be described.

When a failure occurs in the first host 1 from the state where the first host 1 and the third host 3 are connected to the multiple host control device 5 and the inter-host shared resource 4, first The failure detection time processing means 56 which has detected the failure of the host 1 notifies the alternative host determination means 57 of the occurrence of the failure, and the connection detection time processing means 54 and the disconnection detection time processing means 55 of the host state management table 52. The host status management table 52 is instructed to lock the data of each host so as not to change the data. Then, the host status management table 52 is locked so that the stored data cannot be changed in accordance with the instruction of the failure detection processing means 56.

Next, when the second host 2 is connected immediately after the failure of the first host 1, the connection detection time processing means 54
Performs the process of updating the data of the second host 2 in the host status management table 52 to "connection". However, since the data of the host status management table 52 is locked, the second
The update processing of the data of the host 2 is in a standby state.

At this time, the host status management table 52 is in the status shown in Table 2.

[0034]

[Table 2] On the other hand, the alternative host determining means 57 that has received the notification of the failure occurrence of the first host 1 searches the contents of the alternative host definition table 51.

Here, assuming that the contents of the alternative host definition table 51 are set to the same contents as the table 1 shown in the conventional example, the alternative host determining means 57 indicates “disconnect” on the host status management table 52. The host state management table 5 is adopted without adopting the second host 2 which is the first candidate for the alternative host which is
The third host 3, which is the second candidate that is “connected” on the second host 2, is determined as the alternative host of the first host 1.

After the alternative host is determined, the alternative host determining means 57 instructs the host status management table 52 to unlock the data, and the third host 3 is instructed to the first host 1 via the host communication means 53. To instruct recovery processing. Then, the host status management table 52 unlocks the data according to the instruction of the alternative host determining means 57.

When the lock of the data in the host status management table 52 is released, the failure detection processing means 56 updates the data of the first host 1 in the host status management table 52 to "disconnect", and the connection detection processing is performed. The means 54 updates the data of the second host 2 to "connection".

Therefore, when a failure occurs in the host,
Since the data in the host status management table 52 is temporarily locked, the alternative host can be reliably determined without depending on the timing of connection, disconnection, or failure occurrence of the host as in the conventional case. The recovery process is executed reliably.

Further, since the alternative hosts are collectively determined by the plurality of host control devices 5, there is no contradiction caused by having a plurality of alternative host definition tables as in the conventional case, and the illegal operation is eliminated.

In the present embodiment, the case where the number of hosts forming the loosely coupled system is three is described as an example, but the present embodiment can be applied regardless of the number of hosts.

[0041]

Since the present invention is constructed as described above, it has the following effects.

The state of connection or disconnection of a plurality of host computers to the loosely coupled system is stored for each, and when a failure occurs in any of the host computers connected to the loosely coupled system, each of the host computers respectively. Stop updating the stored contents of the state, and from the host computer connected to the loosely coupled system,
By having a plurality of host control devices that determine an alternative host computer that recovers the interrupted processing of the failed host computer and update the stored contents of each state of each host computer after the alternative host computer is determined, Since the alternative host computer is reliably determined without depending on the timing of connection, disconnection, and failure of the computer, the recovery process by the alternative host computer is surely executed.

Further, since the alternative host computers are collectively determined by the plurality of host control devices, there is no contradiction caused by having a plurality of alternative host definition tables as in the conventional case, and the illegal operation is eliminated.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a loosely coupled system according to the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional loosely coupled system.

FIG. 3 is a diagram showing an example of state transitions of three host computers constituting a loosely coupled system.

[Explanation of symbols]

 1 1st host 2 2nd host 3 3rd host 4 Shared resources between hosts 5 Multiple host control devices 11, 21, 31 Loosely coupled system control means 12, 22, 32 Multiple host control device communication means 51 Alternative host definition Table 52 Host status management table 53 Host communication means 54 Connection detection processing means 55 Disconnection detection processing means 56 Failure detection processing means 57 Alternative host determining means

Claims (2)

[Claims] 1. A loosely-coupled system having a plurality of host computers and shared resources between hosts, which are commonly used by the host computers, and states of connection or disconnection of the plurality of host computers to the loosely-coupled system. If any of the stored host computers in the connected state fails, the update of the stored contents of the state of each of the plurality of host computers is stopped, and the interrupted processing of the failed host computer is restored. A plurality of alternative host computers to be selected from among the host computers in the connection state, notify the host computer, and after determining the alternative host computer, update the storage contents of the states of each of the plurality of host computers; A host controller, the plurality of host computers In each of them, a multi-host controller communication means for controlling communication with the multi-host controller, a control for communication between the plurality of host computers, and a control for communication with the inter-host shared resource are provided. A loosely coupled system characterized in that a coupling system control means is provided. 2. The loosely-coupled system according to claim 1, wherein the multiple-host control device controls host communication with a plurality of host computers, and connects the plurality of host computers to the loosely-coupled system. A host state management table that stores disconnection state data, an alternate host definition table that stores candidate alternate host computers for recovering the interrupted processing of a failed host computer for each of the plurality of host computers, and a host When a connection of a computer with a loosely coupled system is detected, a connection detection time processing means for updating the data of the host computer in the host status management table to the connection, and a disconnection of the host computer from the loosely coupled system are detected. In the case of the host computer of the host status management table When a failure is detected from any one of the disconnection detection processing means for updating data to disconnection and the host computer in the connected state, the host state management table is instructed to stop updating, and the host computer fails. The failure detection processing means for notifying the occurrence, and the alternative host computer based on the contents of the alternative host definition table among the host computers connected by the failure detection notification from the failure detection processing means. And a substitute host determining means for instructing the host computer and instructing to release the update stop of the host state management table.