JPH04628A - Recognizing method for subsystem constitution - Google Patents

Abstract

PURPOSE:To enable automatic load distribution of an I/O access by making a logical constitution which can exchange a message between controllers in a shared memory of all controllers, executing successively an access to one piece of external storage device from the respective controllers and recognizing the whole connecting constitution. CONSTITUTION:A controller A 20 is connected to a control adaptor 40 through a path A30, this control adaptor 40 can be accessed to all disk devices 1-3, and it is all the same with regard to other controllers (B, C and D) 21-23, as well. The control adaptors 40-43 sychronize a data transfer between the controllers 20-23 and the disk devices 1-3, and collate the device number in the case the controllers 20-23 select the disk devices 1-3. Also, the controllers 20-23 are provided with a shared memory 24 which can be referred to from any controller, and in the inside of the shared memory 24, message tables 50-53 and a connecting constitution map are provided. In such a way, the connecting constitution is recognized automatically in a subsystem.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a subsystem that controls external storage of a computer system, and particularly to a subsystem that controls external storage of a computer system, and particularly to a subsystem that controls external storage in the subsystem and between an external storage device and an external storage control device (hereinafter referred to as a controller). Concerning how to recognize connection configuration.

[Conventional technology]

Conventionally, external storage devices such as magnetic disk storage devices are C
It usually has two connection paths with the CPU.
Since the controller is simply accessed in response to an access request from the controller and has a simple configuration, there is no particular need for the controller to be aware of the connection configuration.

[Problem to be solved by the invention]

In recent years, magnetic disk storage devices (disk devices) with four connection paths have been developed, and subsystem configurations that include this and the conventional two connection paths are also occurring. . In addition, in order to automatically perform I10 access load balancing between the controller and the disk device, and to satisfy the check function when the disk device is shared between controllers that share the disk cache and controllers that do not share the disk cache, the controller needs to be aware of the connectivity configuration within the subsystem. As configurations themselves have become more complex, even if a method is adopted in which configuration information is sent from the CPU side to subsystems at system startup, there is a possibility that the actual configuration and configuration information may match or mismatch. There are requests to confirm that there are no inconveniences in terms of access.

Therefore, the present invention provides a method that can automatically recognize the connection configuration within the subsystem.

[Means to solve the problem]

In order to recognize the configuration of a subsystem in which a plurality of external storage control devices share and control a plurality of external storage control devices, the present invention provides: A first step of occupying the control device (B) A second step of checking the connection state of the specific external storage device from all external storage control devices other than the one external storage control device (C) The connection state of the specific external storage device The third step is to create a table that stores the data for each external storage control device. The second and third steps are executed for all external storage devices, and the connection relationships of the entire system are recognized from the table.

〔Example〕

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

The configuration of this embodiment will be explained with reference to FIG. In this embodiment, the CPU uses four controllers and eight disk devices to perform external storage.

Controller A20 is connected to control 7gupter 40 via path A30. This control adapter 40 can access all eight disk devices. This is the same for the other controllers (B, C, D), that is, the CPU has four access routes to any disk device.

The controller executes external storage according to instructions from the CPU, and the execution is instructed to the control adapter via a path.

The control adapter has functions such as synchronizing data transfer between the controller and the disk device, and verifying the device number when the controller selects a disk device. The controller has a shared memory 24 that can be referenced by any controller. In particular, in this embodiment, a message table 5 is stored inside this shared memory 24.
0 to 53 (see FIG. 2) and a connection configuration map (see FIG. 4).

This message table will be explained with reference to FIG. Referring to the memory cell table 50, there are request messages and response messages corresponding to each controller (A-D).

The other message tables 51 to 53 have exactly the same configuration. The reason why four message tables are prepared is because, especially in this embodiment, there is always a controller that has command authority when investigating the connection configuration, and a message table that is exclusively used by that controller is required. be. This message table is 'O' and there are no messages.The request messages include a sense command and a test command.The sense command is a command to investigate the connection status of the target disk device.The test command is a command to check the connection status of the target disk device. This is a command to send a message to other controllers to investigate the sense command.On the other hand, the response message is the one that receives the sense command and responds with the investigated connection status.The connection status is "reserved (occupied)". Status”, “Offline status”
, “accessible state” and “reservation complete”.

The controller periodically refers to the request messages for its own system in the four message tables 50 to 53, and when a memory cell is found there, it starts its respective operation.

Next, the configuration recognition method of this embodiment will be explained with reference to the flow shown in FIG.

This flow shows the operation for each controller. First, it is necessary to recognize the configuration, and the CPU writes a test command to the A request message in the message table 50. Controller A20 discovers the test instruction in the request message. (100) Initialize the message table 50 with all "0"s. (103) Reserve 0 (1) of the disk device via the control adapter 40. (104
) The next process branches depending on whether this reservation is completed or not.

(105) Since the controller of another system is not reserving the disk device, the only state in which reservation is not possible is the offline state.

The following operations are meaningless in the offline state, so do not execute them. When the reservation is completed, "reservation complete" is written in the own system response message (106). Then, the sense command for disk device 0(1) is written in the request message of the other controller (], 07). Here controller A
20 enters a response message waiting state (108), but other controllers receive the sense command, sense it, and perform operations 100 to 102 in the flow of writing a response message. After confirming the response message, controller A enters termination processing.

In this embodiment, one disk device is tested by making reservations once from all four controllers. Moreover, the order starts with controller A and ends with controller D. Therefore, CCPTJ first issued a test command to controller A for disk device 0 (1). Therefore, in the termination process, it is first checked whether the own system is the controller D23 (109). If it is the controller D23, all processing has been completed for one disk device, so the message table 50
~53 and select disk device 0 (1) in the connection configuration map.
) and the connection of each controller (110). This map is written with "1" if it is normal, and "0" if it is abnormal or offline. An abnormality is, for example, a state in which sense results of other controllers are accessible even though one controller is serving. Since this result alone cannot tell which controller is incorrectly connected, all message tables are referenced. Next, the symmetric disk device is switched (111). Then, explain whether all disk devices have been tested (
112). If the test is not completed, a test request message is output to the next controller (controller A). Then, the next controller continues from 100 again.

The connection configuration map thus completed is shown in FIG. This example shows that access from the controller C to the disk 7 is impossible.

〔Effect of the invention〕

As explained above, the present invention creates a logical configuration in which messages can be exchanged between controllers in a shared memory shared by all controllers that has a path for connecting an external storage device.
By making it possible to recognize the entire connection configuration by sequentially accessing one external storage device from each controller, it is possible to check for errors in the connection configuration and change the access route at the controller level, allowing automatic I10 access. This has the effect of achieving load distribution.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a subsystem configuration according to the present invention, FIG. 2 is a diagram showing an example of the structure of a message table configured in a shared memory, FIG. 3 is a flowchart showing the operation of the controller, and FIG. 4 1 is a diagram showing an example of a connection configuration map constructed in a shared memory. 1 to 5...disk device, 20 to 23...
... Controller, 24 ... Shared memory, 30
~33...Route A-D, 40-45...
- Control adapter, 50-53...Message table. Agent Patent Attorney Susumu Uchihara

Claims (1)

[Claims] In order to recognize the configuration of a subsystem in which a plurality of external storage control devices share and control a plurality of external storage devices, (a) one of the external storage control devices A first step of occupying an external storage device (b) A second step of checking the connection status of the specific external storage device from all external storage control devices other than the one external storage control device (c) the connection The third step is to create a table that stores the status for each external storage control device.The first, second, and third steps are executed for all external storage devices, and the connection relationships of the entire system are determined from the table. A method for recognizing a subsystem configuration characterized by recognizing it.