Fixes are available
APAR status
Closed as program error.
Error description
WebSphere MQ on Linux does not use direct I/O when writing to the recovery log. The expected default behavior is that direct I/O is used. An 'strace' of strmqm should show two opens per log file, one using the O_DIRECT flag, rather than a single open. For example 23342 open("/var/mqm/log/active/S0000000.LOG",O_RDWR|O_DSYNC)=8 23342 open("/var/mqm/log/active/S0000000.LOG", O_RDWR|O_DSYNC|O_DIRECT) = 9
Local fix
Direct I/O can be explicitly enabled with the following tuning parameter in the qm.ini as follows: TuningParameters: NoLogBuffering=TRUE
Problem summary
**************************************************************** USERS AFFECTED: This issue affects users of IBM MQ on Linux platforms. Users who have deployed MQ using a log filesystem which does not tolerate the use of O_DIRECT should follow the guidance below to disable this optimization. Platforms affected: Linux (s390x),Linux (x86),Linux (x86-64) **************************************************************** PROBLEM SUMMARY: The intention of the code design was to use the O_DIRECT flag when opening recovery log files on Linux platforms. The wrong constant was used when testing for the Linux platform and so the option was not enabled.
Problem conclusion
The constant was corrected so that Linux platforms would use the O_DIRECT flag by default when opening recovery log files. This change in behavior can be overridden by adding the following to the relevant qm.ini file: TuningParameters: NoLogBuffering=FALSE Setting this tuning parameter will cause MQ to revert to the old behavior. --------------------------------------------------------------- The fix is targeted for delivery in the following PTFs: Version Maintenance Level v7.1 7.1.0.5 v7.5 7.5.0.3 The latest available maintenance can be obtained from 'WebSphere MQ Recommended Fixes' http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037 If the maintenance level is not yet available information on its planned availability can be found in 'WebSphere MQ Planned Maintenance Release Dates' http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309 ---------------------------------------------------------------
Temporary fix
Comments
APAR Information
APAR number
IV47558
Reported component name
WMQ LIN X86 V7
Reported component ID
5724H7224
Reported release
710
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2013-08-26
Closed date
2013-09-27
Last modified date
2016-11-21
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
Fix information
Fixed component name
WMQ LIN X86 V7
Fixed component ID
5724H7224
Applicable component levels
R710 PSY
UP
[{"Line of Business":{"code":"LOB45","label":"Automation"},"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSFKSJ","label":"WebSphere MQ"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"7.1"}]
Document Information
Modified date:
08 March 2021