In my testing, clear q on an empty q didn't release the space. It needed to actually clear a message to work. This was on Windows 2000. MQ 5.3.0.8. In case Phil's way doesn't work as expected for you:
Load up a queue with 200,000 Persistent messages. Each 100K in length. Queue File is 20GB. Issue Clear Q command. Q file drops to 1K. Load up a queue with 200,000 Persistent messages. Each 100K in length. Queue File is 20GB. Destructively MQGET all the messages till the queue is empty. Queue file is still 20GB. Issuing Clear Q against the empty q does nothing, still 20 GB Add 1 message to that empty queue with a 20GB file size, and then issue the clear queue command against that one little message, and it shrinks the queue file down to about 1K! -Peter -----Original Message----- From: MQSeries List [mailto:[EMAIL PROTECTED] Behalf Of [EMAIL PROTECTED] Sent: Monday, April 17, 2006 2:40 PM To: [email protected] Subject: Re: sizing disk space on AIX This may be helpful... This was tested for Sun, but I'd doubt it would be very different on AIX. If the messages sent were not removed, and the linear logs were not compressed, then this chart would give you a good idea of the amount of disk space you would need. Of course, reclaiming the space depends upon the behavior of the applications and the frequency your log clean up utility is run. A couple of other points... we give each queue manager its own file system. We alert whenever the file system exceeds 80%. Also, if the queue is empty, and you issue a clear queue, then WMQ will release all but 1620 bytes back to the OS for reuse. Queue space is allocated and grows as long as the queue depth and message sizes grow. The queue space is not normally returned to the OS until the queue is cleared or a qmgr recycle occurs. It may also release queue space after a WMQ overall checkpoint occurs. (not too sure when this occurs...). (Embedded image moved to file: pic05829.jpg) Robert Broderick <[EMAIL PROTECTED] To: [email protected] COM> cc: Sent by: MQSeries List Subject: Re: sizing disk space on AIX <[EMAIL PROTECTED] WIEN.AC.AT> 04/17/2006 01:58 PM Please respond to MQSeries List That would be goo if you had two applications and both sent in the same amount of messages per hour/day/week/month. What you need to do is figure out what each application will send in numbers and size. Per QMGR. THis would include both intr and extr QMGR messages. Now if your QMGR and application are humming along perfectly you could basically say How much space do I need within one hour. Ahhhh but this isn't a perfect world. So now you have to start considering what happens when some bonehead for the receiving application puts in a code change and the pitcher throw the ball and there is no one there to catch it. How long will it be OK for this condition to exist. Will the pitcher keep throwing the ball. You could end up drowning the umpire!! Now, what happens in a failover situation. Things have to move and it will be a good bet ALL the applications will not come up perfect. You need somewhere to store these messages. What do the SLA's indicate. I will tell you. In a DR there will be a lot of yelling later on but you can use your SLA in the bathroom as paper. So what I usually do, and everyone is different, but the main idea is to be safe. I figure out what a day would cost me in bytes. I multiple that by two for matrixes' that were not correct and then by 2 for two days worth of work. If this comes in nice you will have plenty of room to grow. Oh....that was something else I forgot to mention!!!! Once you buy the storage it is static in cost. But you do not want to go back to infrastructure 6 months (if you can last that long) and tell them you need to purchase MORE hardware. Hit them hard and hit them fast I always say!!! Just my 1.588798566354373389 cents bobbee Date: Mon, 17 Apr 2006 12:35:19 -0400 From: [EMAIL PROTECTED] Subject: sizing disk space on AIX To: [email protected] It's more of a general question regarding sizing disk space on unix. Unlike the mainframe, where a couple of formulas are provided to help you size the disk space needed for a queue manager, there isn't anything like that for unix. What are others doing? Are they simply taking the average size of all messages, slapping on the MQMD and XMIT header, and then converting that into total bytes required? 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