Testing and support statement for WebSphere MQ multi-instance queue managers

Technote (FAQ)


Question

What are the requirements for networked storage for multi-instance queue managers? Which environments have IBM used to test multi-instance queue managers?

Answer

To use the multi-instance queue manager feature of WebSphere MQ, you will need a shared file system on networked storage, such as a NAS, or a cluster file system, such as IBM's General Parallel File System (GPFS). You can use a SAN as the storage infrastructure for the shared file system.
Shared file systems must provide data write integrity, guaranteed exclusive access to files and release locks on failure to work reliably with WebSphere MQ.

There are three fundamental requirements that a shared file system must meet to log messages reliably.

  1. Data write integrity.
    Data write integrity is sometimes called "Write through to disk on flush". The queue manager must be able to synchronize with data being successfully committed to the physical device. In a transactional system, you need to be sure that some writes have been safely committed before continuing with other processing and that the ordering of writes across multiple files is honored.
  2. Guaranteed exclusive access to files.
    In order to synchronize multiple queue managers, there needs to be a mechanism for a queue manager to obtain an exclusive lock on a file.
  3. Release locks on failure.
    If a queue manager fails, or if there is a communication failure with the file system, files locked by the queue manager need to be unlocked and made available to other processes without waiting for the queue manager to be reconnected to the file system. Modern file systems, such as NFS v4, use leased locks to detect failures and then release locks following a failure. Older file systems, such as NFS v3 that do not have a reliable mechanism to release locks after a failure, must not be used with multi-instance queue managers.

A shared file system must meet these conditions for WebSphere MQ to operate reliably. If it does not, the queue manager data and logs get corrupted when using the shared file system in a multi-instance queue manager configuration.

On operating systems other than Microsoft Windows, WebSphere MQ provides a tool called amqmfsck to assist with checking the suitability of networked storage for use with multi-instance queue managers. This can be used to verify the basic configuration of the networked storage, such as access permissions. It can also assist with the second and third of the requirements above. It cannot check that data write integrity is maintained because it cannot observe whether data is being safely committed to disk as opposed to being held in a cache.

For multi-instance queue managers on Microsoft Windows, the networked storage must be accessed by the Common Internet File System (CIFS) protocol used by Microsoft Windows networks.

IBM has not tested multi-instance queue managers with CIFS on platforms other than Microsoft Windows.

For multi-instance queue managers on other supported platforms, the storage must be accessed by a network file system protocol which is Posix-compliant and supports lease-based locking. Network File System version 4 (NFS v4) satisfies this requirement. Please note that earlier versions of NFS do NOT satisfy this requirement and must not be used with multi-instance queue managers.

Multi-instance queue managers do not work with mandatory file locking. The NFS support provided by some NAS devices enforces mandatory file locking. While this is permitted by the NFS v4 specification, multi-instance queue managers were designed to use the less restrictive advisory file locking scheme and are not compatible with mandatory file locking. IBM has encountered mandatory file locking only with NAS devices from the EMC Celerra family. Please note that the version of amqmfsck supplied with WebSphere MQ v7.0.1 does not test for mandatory file locking, although later versions do.

For WebSphere MQ on IBM i, NFS v4 is not supported and you have the alternative option of networked storage using IBM i5/OS NetServer.

IBM performed most of the testing of multi-instance queue managers in the following environments. In some cases, other versions of the operating systems are also supported. Please refer to the system requirements information for WebSphere MQ for a complete list of the supported platforms.

Operating system for the multi-instance queue manager
Networked storage environment
NFS v4 server on Sun Solaris 10 NFS v4 server on IBM AIX 5.3 plus TL10 NFS v4 server on IBM System Storage N series system running Data ONTAP 7.3.2 IBM General Parallel File System V3.2.1 NFS v4 server on SUSE Linux Enterprise Server (SLES) V10 NFS v4 server on Red Hat Enterprise Linux 5.3 IBM i5/OS NetServer V6R1 Microsoft Windows Server 2008
IBM AIX 5.3 TL10, see note 4 Yes Yes Yes Yes Yes
Oracle Solaris 10 on SPARC with IDR 145513 revision 3 Yes, but see note 1
Red Hat Enterprise Linux 5.3 Yes
SUSE Linux Enterprise Server (SLES) V10 Yes, but see note 2 Yes, but see note 2
HP-UX 11i v3 (11.31) Yes
IBM i5/OS V6R1 Testing failed, see note 3 Yes
Microsoft Windows Server 2008 Yes

Notes:
  1. Multi-instance queue managers on Solaris using NFS v4 require Solaris 10 with patch 147440-13 (SPARC) or patch 147441-13 (x86-64). This patch supersedes IDR 145513 revision 3 and patch 147268-01 (SPARC), and IDR 145514 revision 3 and patch 147269-01 (x86-64) which are no longer supported.
  2. SLES V10 Update 3 introduced a suspected problem in the NFS v4 server which prevents correct operation of multi-instance queue managers. The problem was rectified in kernel level 2.6.16.60-0.60.1.
  3. Multi-instance queue managers on IBM i using NFS v4 are NOT supported.
  4. Multi-instance queue managers on IBM AIX 5.3 TL6 to TL9 using NFS v4 require AIX APAR IZ29559 (or equivalent for the specific technology level).

The following additional environments have also been tested specifically to validate the file system's suitability for use with WebSphere MQ.

Operating system for the multi-instance queue manager
Networked storage environment
Veritas Storage Foundation V5.0 MP3 RP3 Cluster File System Veritas Storage Foundation V5.1 SP1 Cluster File System Red Hat Global File System 2 (GFS2) Oracle Cluster File System 2 (OCFS2) 1.4 on SUSE Linux Enterprise Server (SLES) V10 SP3 Oracle ASM Cluster File System (ACFS) 11g R2
Red Hat Enterprise Linux 5.4 Yes
Oracle Solaris 10 9/10 Yes
Red Hat Enterprise Linux 6.3 Yes
SUSE Linux Enterprise Server (SLES) V10 SP3 Testing failed, see note 1
Red Hat Enterprise Linux 5.8 Testing failed, see note 2

Notes:
  1. Multi-instance queue managers are not supported on OCFS2 1.4.
  2. Multi-instance queue managers are not supported on Oracle ASM Cluster File System (ACFS).

Other environments which meet the technical requirements for the networked storage are also supported.

The following file systems are known not to meet the technical requirements and are not supported for use with multi-instance queue managers:
  • Network File System (NFS) version 3 - does not provide lease-based file locking.
  • Red Hat Global File System (GFS, or GFS1) - does not provide the correct locking semantics. Note that the later GFS2 is supported for use with multi-instance queue managers.
  • Oracle Cluster File System version 2 (OCFS2) - does not provide the correct locking semantics in version 1.4. Testing will be required on later versions to see if the required support has been added.
  • Oracle ASM Cluster File System (ACFS) - does not provide the correct locking semantics. Cluster-wide advisory file locking is not supported.

Product Alias/Synonym

WMQ MQ

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Document information


More support for:

WebSphere MQ
Multi-Instance

Software version:

7.0.1, 7.1, 7.5

Operating system(s):

AIX, HP-UX, IBM i, Linux, Solaris, Windows

Reference #:

1433474

Modified date:

2013-05-06

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