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| Max message size and Max queue size |
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| lwl |
 Posted: Wed Sep 01, 2004 6:31 pm Post subject: Max message size and Max queue size |
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Apprentice
Joined: 30 Mar 2004
Posts: 41
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Hi
We are using MQ v5.3, CSD06.
My question is:
1. what is the maximum size of a single message?
2. what is the maximum size of messages stored in a queue? (is it related to MAXMSGL, how large can it be set?)
3. what is the maximum number of messages stored in a queue? (is it related to MAXDEPTH, how large can it be set?)
Thank you
lwl  |
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| kman |
| Posted: Wed Sep 01, 2004 6:48 pm Post subject: |
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Partisan
Joined: 21 Jan 2003
Posts: 309
Location: Kuala Lumpur, Malaysia
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Take a look at the Quick Beginnings Guide, Application Programming Reference, Application Programming Guide to find out. I hope these docs has it mentioned somewhere. Follow the 'documentation' link from the top of the page.
On Dist. Platform, WMQ v5.3 single message can be 100 MB. The message size in the queue is the same. You can alter the queue to change the MAXMSGL. That parameter is to tell what is the size of the message on the queue. It is set to a good value by default, but you can change that.
maximum number of messages on the queue depends on your system, but should not exceed 2 GB in total length per queue. Pls be reminded, WMQ is not a database, and should not be used as such. So remove the message immediately by running your application to service the queue (i.e., Get the message).
My info above is off my head. May not be correct. Check out the docs. |
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| kirani |
| Posted: Wed Sep 01, 2004 10:16 pm Post subject: Re: Max message size and Max queue size |
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Jedi Knight
Joined: 05 Sep 2001
Posts: 3779
Location: Torrance, CA, USA
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| lwl wrote: |
3. what is the maximum number of messages stored in a queue? (is it related to MAXDEPTH, how large can it be set?)
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I think on non-M/f system it can be set to 640,000.
_________________
Kiran
IBM Cert. Solution Designer & System Administrator - WBIMB V5
IBM Cert. Solutions Expert - WMQI
IBM Cert. Specialist - WMQI, MQSeries
IBM Cert. Developer - MQSeries
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| kman |
| Posted: Wed Sep 01, 2004 11:44 pm Post subject: |
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Partisan
Joined: 21 Jan 2003
Posts: 309
Location: Kuala Lumpur, Malaysia
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| Quote: |
WebSphere MQ Version 5.3 supports queues larger than 2 GB. On Windows systems, support for large files is available without any additional enablement. On AIX, HP-UX, Linux, and Solaris systems, you need to explicitly enable large file support before you can create queue files larger than 2 GB. See your operating system documentation for information on how to do this.
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So my thought was right. It was 2 GB. MAXDEPTH is the number of messages. Well if the messages is 1 MB each, you can't reach maxdepth 640k . |
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| PGoodhart |
| Posted: Thu Sep 02, 2004 5:21 am Post subject: |
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Master
Joined: 17 Jun 2004
Posts: 278
Location: Harrisburg PA
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We are using MQ v5.3, CSD06.
(This is important, different versions have different levels. Different Platforms also have effects)
My question is:
1. what is the maximum size of a single message?
It depends...
This can be affected by several queue and queue manager settings, circular logging, message persistence, segmentation, platform, etc. With segmentation a single logicial message is as large as your storage medium.
2. what is the maximum size of messages stored in a queue? (is it related to MAXMSGL, how large can it be set?)
The size of the queue is unlimited, so your storage medium defines this.
MAXMSGL actually is the limit on the size of a single physical message, and depending on platform you are looking at 100 MBs or more. In actual practice you will most likely want to set this to something like 4 MB, and segement larger messages.
3. what is the maximum number of messages stored in a queue? (is it related to MAXDEPTH, how large can it be set?)
The depth is unlimited if MAXDEPTH is unset and you don't consume all the storage. I believe MAXDEPTH's limit is something like 99999999 on most of the platforms.
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Patrick Goodhart
MQ Admin/Web Developer/Consultant
WebSphere Application Server Admin |
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| kman |
| Posted: Thu Sep 02, 2004 7:47 pm Post subject: |
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Partisan
Joined: 21 Jan 2003
Posts: 309
Location: Kuala Lumpur, Malaysia
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You may also be interested on this link,
http://www-1.ibm.com/support/docview.wss?uid=swg21040449
Though it was based on MQ 5.2, but the statement still holds.
IN case you can't get to the link, here it is;
| Quote: |
MAXDEPTH=640000 dates back to the times when the maximum queue file size was limited to 320MB. The minimum message size is 512 bytes and 512*640KB=320MB. The maximum size for the queue file is currently 2GB. We are currently investigating raising this limit in a future
release. |
Here's what I think of it.
A single message size is 100MB. But if you segment the messages, it can be any size. Or rather multiple messages of max 100MB can be reconstructed into 1 single message of very big size.
Queue limit on certain platform is initially set at 2 GB. And can go beyond that on Windows automatically, so the max msg size in the queue can be anything. Number of messages also can be anything.
But if it is persistent message, the the size of the log determine the size of the message. If non-persistent, the size of the memory determine the size of the message.
As I can remember Windows (w2k?) has a limit of 2GB memory, so if all messages are non persistent, they are all on the memory. They can't take all the 2GB.. and so it goes... |
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| PeterPotkay |
| Posted: Fri Sep 03, 2004 5:00 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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| Quote: |
...so if all messages are non persistent, they are all on the memory.
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Not true.
There is a Space Table kept to manage the space in the queue buffer and the queue file.
NP messages are stored in a shared memory buffer by preferance. If the buffer overflows, they are written to the file system buffer but there is never a synchronous disk write for NP messages.
When a PUT happens, and the message is persistent, it will be allocated space in the queue file. If the message is non persistent, it will be allocated space in the queue buffer, or in the queue file if the buffer is full.
LOGS - If the message is persistent, there will normally be 1 log record written. If the message is not persistent, there is no write to the log record, even if the message spilled over to the queue file.
There is an exception to the rule of persistent messages being written to logs. If an app does an MQPUT outside of syncpoint to a queue where there is an MQGET waiting outside of syncpoint, the persistent message is passed thru in memory with no writes to the log.
If the space was allocated in the queue buffer, the message data is copied to the queue buffer. If the space was allocated to the queue file, the data will be written to the queue file via the file system buffer. If a log record is needed to record the update, it will be written before the message data is written to the queue file. If the message is put under syncpoint, neither write will by synchronous. A synchronous write to the log will be required when the transaction is committed or rolled back.
_________________
Peter Potkay
Keep Calm and MQ On |
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| sstubble |
| Posted: Tue Sep 18, 2007 10:31 am Post subject: |
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Novice
Joined: 09 Dec 2005
Posts: 20
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I just had to research this because we are  using WMQ as a database right now. We are running V5.3 CSD 13 on AIX 5.2. According to my AIX admin, the JFS2 file system will allow a single file (i.e. q) to grow to 16 terabytes in size. JFS is limited to 2GB. |
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| jefflowrey |
| Posted: Tue Sep 18, 2007 10:46 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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The limitations on the size of the q files changed in v6, too.
Yet another compelling reason to upgrade.
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I am *not* the model of the modern major general. |
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| fjb_saper |
| Posted: Tue Sep 18, 2007 3:28 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| sstubble wrote: |
| I just had to research this because we are using WMQ as a database right now. |
That is going to bring you another can of worms.
If you have to, use a real DB, and have the messages there by msgid or correlid in a BLOB or CLOB ....
DO NOT USE MQ as a DB. You're just asking for trouble... 
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MQ & Broker admin |
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