JPH05216699A - Path fault processing system of external storage device - Google Patents

Abstract

PURPOSE:To prevent the performance of the system from being degraded by promoting the retrial of the exchange path even when a path fault occurs intermittently and repeatedly and further blocking the fault path early. CONSTITUTION:An external storage device 33 is connected with an OS12 and plural connection paths for its significance and it is composed so that the input/ output operation may be continued in the exchange path even when a path is impossible to be used due to a fault. In this case, an external storage control device 31 classifies the occurred fault into the fault of the common part in the external storage sub-system 30 and a path fault, and increases the count in a path fault cumulative counter 32 installed in the external storage control device 31 when the fault is the path fault. The part exhibiting the fault processing request classification to an input/output control part 16 is provided within the detailed information generated by the external storage control device 31. The input/output control part 16 which received this report selects the fault processing according to the fault processing request classification and a source state table 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information processing system, and more specifically, an OS running on a host processor.
Relates to a path failure processing method for managing the state of an external storage device connected to a host processor by a plurality of paths.

[0002]

2. Description of the Related Art In an information processing system, when an external storage device detects some kind of failure and abnormally terminates the input / output operation, detailed information indicating the status of the failure is generated, and the detailed information is generated.
Report to S. Conventionally, it has been general to present in the detailed information whether the route is a fault or the fault of a common part that does not depend on the route. The OS judges the information of the common part failure or the path failure and retries the abnormally ended input / output operation as follows.

First, in the case of a common part failure, the input / output operation is retried a prescribed number of times on the failure path. Next, in the case of a route failure, a retry is performed a prescribed number of times on the faulty route, and if this cannot be relieved, a retry is performed a prescribed number of times on the alternate route. When there is no available alternative route, the same failure processing as the former is performed. If the rescue is successful by retrying on the alternate route, the alternate route operation is normal, and the failed route has already failed multiple times, and the failed route was used for subsequent I / O operations. In this case, since the same type of failure is likely to occur, the failure path is blocked so as not to be used in the subsequent input / output operation. The purpose of this path blockage is to avoid the use of paths with a high probability of failure and avoid the increase in system overhead due to failure processing.

[0004]

By the way, although line faults are intermittent, if the frequency of faults increases in an environment where they repeatedly occur, the number of faulty line retries increases correspondingly and pressures the system performance. There was a problem to do.
Moreover, since the failure route is relieved by the retry, the conventional method does not close the failure route and continues to use the failure route for subsequent input / output operations.
An object of the present invention is to solve the above problems, and to provide a path failure processing method for an external storage device, which reduces the chance of using an unstable path and prevents deterioration of system performance due to useless retry processing. is there.

[0005]

In order to achieve the above object, a path failure processing method for an external storage device according to the present invention is an external storage device in which an OS running on a host processor is connected to the host processor through a plurality of paths. In the above method, the external storage device counts the cumulative number of occurrences of path failures, and when the path failure occurs after the cumulative number of occurrences of path failures exceeds a threshold value, abnormal termination of I / O operation is performed. OS
It also reports that the cumulative number of occurrences of path failures exceeds the threshold value when reporting to the OS. If the replacement path exists, the OS that has received the report indicates that there is no replacement path on the replacement path. It is configured to retry the I / O operation on the fault path. In addition to the above configuration, the present invention is configured to block the initial failure route when the alternate route exists and the input / output operation retried on the alternate route succeeds.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an information processing system adopting a line fault processing method for an external storage device according to the present invention. The information processing system of this embodiment is physically composed of a host processor 10, an input / output channel group 20, and an external storage subsystem 30. OS
A program 12 runs on the host processor 10 and manages the entire information processing system such as the job management unit 13 and the resource management unit 14. A resource status table 17 is provided in a part of the resource management unit 14 of the OS 12,
The state of each resource in the information processing system which can be used by 12 is grasped.

The input / output channel group 20 is a connecting portion for connecting the host processor 10 and the external storage subsystem 30 and is used as a part of an access path from the OS 12 to the external storage subsystem 30. The external storage subsystem 30 comprises a plurality of external storage devices 33 and a plurality of external storage control devices 31 for exchanging data between the external storage devices 33 and the input / output channels 20. The external storage device 33 is connected to the OS 12 by a plurality of connection routes because of its importance, and is configured so that even if a certain route becomes unusable due to a failure, the input / output operation can be continued through the alternate route. The external storage control device 31 is arranged on each path.

The input / output request issued by the application program 11 is executed under the control of the input / output control unit 16 in the OS 12 via the file management unit 15 in the OS 12. The input / output control unit 16 uses the resource status table 1
7, one available path is selected from a plurality of paths to the external storage device 33 to be accessed, and an input / output instruction is issued to the input / output channel 20 on the selected path. The issued input / output instruction is executed by the combined operation of the input / output channel 20 and the external storage controller 31,
Detailed information indicating the presence or absence of a failure and the status of the failure is returned to the input / output control unit 16 as the end result of the input / output instruction. A failure in the input / output operation occurs in the input / output channel 20, the external storage controller 31 or the external storage device 33,
Of these, detailed information is generated in the external storage control device 31 regarding the failure that has occurred in the external storage control device 31 and the external storage device 33.

The external storage control device 31 classifies the generated faults into a common portion fault and a route fault in the external storage subsystem 30, and in the case of a route fault, a route fault cumulative counter installed in the external storage control device 31. Increment 32. In the detailed information generated by the external storage control device 31, there is provided a portion for presenting the type of fault processing request to the input / output control unit 16, and the "route fault whose cumulative route fault counter is less than the threshold value", "route fault" Either "path failure whose cumulative counter is greater than or equal to a threshold value" or "not path failure" is stored. The input / output control unit 16 that has received this report selects the failure processing according to the failure processing request type and the resource status table 17.

FIG. 2 is a flow chart for explaining the operation procedure of the input / output control unit. First, it is determined whether or not there is an alternate route (step 1), and if it is unavailable, retry is performed on the fault route regardless of the type of fault processing request (step 7). On the other hand, when the alternate route is available, the failure processing request type is determined (step 2) and the following failure processing is executed. If the path is not a path failure, the failed path is retried (step 7). In the case of "path failure", it is judged whether or not "path failure in which the path failure cumulative counter is less than the threshold value" (step 3). In the case of "a route fault in which the route fault cumulative counter is less than the threshold value", after a specified number of retries on the faulty route (step 4), it is judged whether or not the repair is possible (step 5). If it can be remedied, it ends as a retry success. If it cannot be repaired, the process proceeds to the retry on the alternate route (step 9). Further, in the case of "a route fault in which the route fault cumulative counter is equal to or more than the threshold value", the process immediately proceeds to step 9 and retry is performed on the alternate route.

When the fault is relieved by either the fault route retry or the alternate route retry, the input / output control unit 16 notifies the application program 11 as the input / output request source that the input / output operation has been normally completed. To do. Further, when the input / output control unit 16 retries the alternate route and rescues it on the alternate route in the process of the failure processing, the resource state table 17
Make the initial failure path unavailable above (step 1
1). On the other hand, the external storage control device 31 executes individual input / output instructions, and whether each input / output instruction is an initial instruction, a failure route retry instruction, or an alternate path retry instruction. Is not determined. Therefore, the failure processing request type is just a request, and the failure processing type is determined by the judgment of the input / output control unit 16.

[0012]

As described above, according to the present invention,
Even if a route failure occurs intermittently but repeatedly, it is configured so that alternate route retries can be promoted and the failed route can be blocked early. It is possible to prevent the occurrence of a more serious failure that tends to occur by continuously using the unstable route while preventing the deterioration of the power consumption.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a path failure processing method of an external storage device according to the present invention.

FIG. 2 is a flow chart for explaining a failure process of the input / output control unit of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Host processor 11 ... Application program 12 ... OS (Operating system) 13 ... Job management unit 14 ... Resource management unit 15 ... File management unit 16 ... Input / output control unit 17 ... Resource status table 20 ... Input / output channel 30 ... External storage Subsystem 31 ... Storage control device 32 ... Path failure cumulative counter 33 ... External storage device

Claims (2)

[Claims] 1. An operating system running on a host processor comprises:
A method of managing the state of an external storage device connected to a host processor by a plurality of routes, wherein the external storage device counts the cumulative number of occurrences of path failures, and the cumulative number of occurrences of path failures exceeds a threshold value. When a subsequent path failure occurs, it also reports that the cumulative number of times of path failure occurrence exceeds the threshold value when reporting the abnormal termination of the input / output operation to the OS, and the OS receiving the report, if an alternate path exists, On this alternate route, if there is no alternate route, the I / O operation is retried on the current fault route. 2. The alternate path exists, and when the input / output operation retried on this alternate path is successful, the initial failure path is closed. Line fault handling method for external storage device.