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| warrenJ |
 Posted: Mon Feb 02, 2009 12:41 am Post subject: 2056 error and DefaultQFileSize on AIX |
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Apprentice
Joined: 11 Jan 2004
Posts: 29
Location: AUSTRALIA
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Hi,
Can someone please confirm what is the deafult maximum disk queue size on AIX (MQ is v6.0.2.5) - I cannot find it documented anywhere. Also there seems to be little documentation on the impacts of increasing it via theDefaultQFileSize setting in qm.ini to a large value (eg. 2Gb) - can it be set to this size ?
I ask because we had a Production problem today where messages were being written to the Dead Letter queue with a reason code 2056 (Queue Space Not Available). All applications connected to the QMgr were reporting problems. The /var/mqm/ directory was only using 18% disk space. I discovered that the actual queue refered to in the 2056 Dead Letter messages was holding 75,000 for a system that had only reads the messages 3 times a day. The actual queue file in /var/mqm/qmgrs/QMGR/queues/queue_name was 1.07Gb, after clearing 20,000 messages from the queue the QMgr was OK and no more messages were going to the Dead Letter Queue.
We're looking at getting the application to process the messages more often but it would be good to have a bigger buffer on the queue size if I can. |
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| Vitor |
| Posted: Mon Feb 02, 2009 1:18 am Post subject: Re: 2056 error and DefaultQFileSize on AIX |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| warrenJ wrote: |
| Can someone please confirm what is the deafult maximum disk queue size on AIX (MQ is v6.0.2.5) - I cannot find it documented anywhere. |
AFAIK it's the same as the maximum size of a file on your OS/hardware combination.
http://publib.boulder.ibm.com/infocenter/wmqv6/v6r0/topic/com.ibm.mq.amqaac.doc/aq10270_.htm Also there seems to be little documentation on the impacts of increasing it via theDefaultQFileSize setting in qm.ini to a large value (eg. 2Gb) - can it be set to this size ?[/quote]
Yes - see here for details. IIRC you have to enable large file support in AIX as well; not entirely certain I'm right on that.... 
Don't forget that no matter how much space you supply, the queue will consider itself full when it hits MaxDepth. If the queue's only read 3 times a day ensure this value is high enough.
But of course you knew that. 
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| PeterPotkay |
| Posted: Mon Feb 02, 2009 6:13 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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warrenJ, for your problem, focus on the queue's Max Message Size and Max Depth parameters, as well as enabling the largefiles option on your server.
DefaultQFileSize is only for performance tuning and trying to keep messages in memory versus spilling over to disk, for queues that are contantly being drained of new messages. That is not your problem. Going to disk is OK for you.
_________________
Peter Potkay
Keep Calm and MQ On |
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| warrenJ |
| Posted: Mon Feb 02, 2009 7:51 pm Post subject: |
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Apprentice
Joined: 11 Jan 2004
Posts: 29
Location: AUSTRALIA
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Thanks for your help. I'll document the real problem here for reference.
The operating system file limit was 1Gb (1048575 blocks * 1024 bytes)...
[mqm@xxxxxx:/data/home/mqm]> ulimit -a
core file size (blocks, -c) 1048575
data seg size (kbytes, -d) 131072
file size (blocks, -f) 1048575
max memory size (kbytes, -m) 32768
open files (-n) 2000
pipe size (512 bytes, -p) 64
stack size (kbytes, -s) 32768
cpu time (seconds, -t) unlimited
max user processes (-u) 128
virtual memory (kbytes, -v) unlimited |
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| mqjeff |
| Posted: Tue Feb 03, 2009 2:20 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| Be aware that ulimit is embedded into files. If you change ulimit you have to recreate your queues to get them to use the new ulimit. |
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| warrenJ |
| Posted: Tue Feb 03, 2009 2:58 am Post subject: |
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Apprentice
Joined: 11 Jan 2004
Posts: 29
Location: AUSTRALIA
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Thanks for the advice - I'll delete and recreate any queues that may hold a huge number of messages (about 3 of them).
We've just moved our critical servers from Windows to AIX so we've just got a couple of teething problems (we've got AIX QMgrs already but they're low usage ones). Great responses, Thanks. |
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