amqmfsck (file system check)

amqmfsck checks whether a shared file system on UNIX and IBM® i systems meets the requirements for storing the queue manager data of a multi-instance queue manager.

Purpose

The amqmfsck command applies only to UNIX and IBM i systems. You do not need to check the network drive on Windows. amqmfsck tests that a file system correctly handles concurrent writes to a file and the waiting for and releasing of locks.

Syntax

Read syntax diagramSkip visual syntax diagram amqmfsck -v -a-c-f-p262144PageCount-i-w- x DirectoryName

Required parameters

DirectoryName
The name of the directory to check.

Optional parameters

-a
Perform the second phase of the data integrity test.
  • Run this on two machines at the same time. You must have formatted the test file using the -f option previously

-c
Test writing to a file in the directory concurrently.
-f
Perform the first phase of the data integrity test.
  • Formats a file in the directory in preparation for data integrity testing.
-i
Perform the third phase of the data integrity test.
  • Checks the integrity of the file after the failure to discover whether the test worked.
-p
Specifies the size of the test file used in the data integrity test in pages. .
  • The size is rounded up to the nearest multiple of 16 pages. The file is formatted with PageCount pages of 4 KB.
  • The optimum size of the file depends on the speed of the filesystem and the nature of the test you perform. If this parameter is omitted, the test file is 262144 pages, or 1 GB.
  • The size is automatically reduced so that the formatting completes in about 60 seconds even on a very slow filesystem.
-v
Verbose output.
-w
Test waiting for and releasing locks.
-x
Deletes any files created by amqmfsck during the testing of the directory.
  • Do not use this option until you have completed the testing, or if you need to change the number of pages used in the integrity test.

Usage

You must be an IBM MQ Administrator to run the command. You must have read/write access to the directory being checked.

[IBMi]On IBM i, use QSH to run the program. There is no CL command.

The command returns an exit code of zero if the tests complete successfully.

The task, Verifying shared file system behavior, describes how to use amqmfsck to check the whether of a file system is suitable for multi-instance queue managers.

Interpreting your results

If the check fails, the file system is not capable of being used by IBM MQ queue managers. If the tests fail, choose verbose mode to help you to interpret the errors. The output from the verbose option helps you understand why the command failed, and if the problem can be solved by reconfiguring the file system.

Sometimes the failure might be an access control problem that can be fixed by changing directory ownership or permissions. Sometimes the failure can be fixed by reconfiguring the file system to behave in a different way. For example, some file systems have performance options that might need to be changed. It is also possible that the file system protocol does not support concurrency sufficiently robustly, and you must use a different file system. For example, you must use NFSv4 rather than NFSv3.

If the check succeeds, the command reports The tests on the directory completed successfully. If your environment is not listed as supported in the Testing and support statement for IBM MQ multi-instance queue managers, this result does not necessarily mean that you can run IBM MQ multi-instance queue managers successfully.

You must plan and run a variety of tests to satisfy yourself that you have covered all foreseeable circumstances. Some failures are intermittent, and there is a better chance of discovering them if you run the tests more than once.