Dean, Ahhh, those pesky developers! They always seem to prefer hard limits to MQ's soft limits. If you bump the Max Uncommitted Messages parm, then you are likely to run into issues of log space (circular logs) or possibly filesystem space (linear logs). And yes, rollbacks of that many messages can bring a QMgr to a momentary halt.
Remember, the Max Uncommitted Messages is for ALL processes. If you have one process that hits it, then other processes on the same QMgr will be impacted as well. MQ's soft limit parms (Max Uncommitted Messages, QDepth, Max Msg Length, etc.) are generally too high. For example, the DeadQ default of 640,000 max depth and 4MB messages equates to way more space than is generally available in the physical filesystem. If you use large messages, the default Max Uncommitted Messages easily exceeds the default space in the circular logs. Whenever an application wants to bump MQ's soft limits, it's a good idea to sit down with them and look at message size, volumes, peaks, etc. I have NEVER found an application that truly required that many messages in one unit of work once we sat down and discussed it in detail. Still, I always leave that possibility open in the discussion. If it works out that they REALLY need that many uncommitted messages, you will need to evaluate your log method and sizes. Circular logs must be large enough to handle all the expected messages plus a "fudge factor" of 20~50%. If you use linear logs, you may need to run the cleanup script against them several times a day so they don't overrun your file system. -- T.Rob -----Original Message----- From: Dean Montevago [mailto:[EMAIL PROTECTED] Sent: Tuesday, December 16, 2003 12:54 PM To: [EMAIL PROTECTED] Subject: Max Uncommitted Messages Hi, What is the trade off in having the max uncomitted messages set to low or to high. The default looks like 10,000. We have an app that wanted to drop 20,000 messages onto a queue. They received : MQRC_SYNCPOINT_LIMIT_REACHED X'7E8' No more messages can be handled within current unit of work. They want to change the max messages to 100,000. I feel this is to high. If they had 90,000 messages on the queue and had to roll back for whatever reason, this could cause issues right ? Any advise would be great. TIA Dean Dean Montevago Sr. Systems Specialist Visiting Nurse Service of New York phone: (212) 609 - 5596 email: [EMAIL PROTECTED] Instructions for managing your mailing list subscription are provided in the Listserv General Users Guide available at http://www.lsoft.com Archive: http://vm.akh-wien.ac.at/MQSeries.archive Instructions for managing your mailing list subscription are provided in the Listserv General Users Guide available at http://www.lsoft.com Archive: http://vm.akh-wien.ac.at/MQSeries.archive
