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| poulter90 |
 Posted: Thu Jan 31, 2008 6:54 am Post subject: MQseries V 5.3 estimating Log size |
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Apprentice
Joined: 31 Dec 2007
Posts: 36
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I am trying to find out the formula for estimating my Log size
on a new UNIX HP Queue-Manager
Log should handle :
1 million messages(2024KB each) per day
Persistent message should be available up to 5 days .
Thanks for your help |
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| Vitor |
| Posted: Thu Jan 31, 2008 7:02 am Post subject: Re: MQseries V 5.3 estimating Log size |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| poulter90 wrote: |
Persistent message should be available up to 5 days .
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This has nothing direcrly to do with log size. Persistent messages a) are held in the queue files not the log files and b) stay there until read off the queue.
So what it appears you need is enough space wherever you're hosting the queues to hold 5 days worth of messages (presumably maximum application down time?) and logs large enough to hold the maximum transaction size that will be open (circular logging) or 5 days of messages (linear logging). This is dependent on how your application handles UOW.
There is also a school of though that says you should define as much log as you have space for and use that.
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| jefflowrey |
| Posted: Thu Jan 31, 2008 7:05 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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If you are creating a new queue manager on a new machine, you should be using MQ v6.
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| fjb_saper |
| Posted: Thu Jan 31, 2008 3:13 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20767
Location: LI,NY
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Guys did you check his numbers?
Assuming all messages to be persistent...
I don't know of a log capable of holding 9651.18 GB. Oh wait, isn't that called a DATABASE ??
(1,000,000 * 2MB *5(days)) ???
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| PeterPotkay |
| Posted: Thu Jan 31, 2008 4:09 pm Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7723
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F.J.,
The logs don't have to be big enough hold all the persistent messages. Just big enough to hold the U.O.W.s.
(For example, create a default QM which gives you about 5 MB of logs. Then go ahead and put gigs and gigs of persistent messages into the queues)
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Peter Potkay
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| fjb_saper |
| Posted: Thu Jan 31, 2008 4:21 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20767
Location: LI,NY
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| PeterPotkay wrote: |
F.J.,
The logs don't have to be big enough hold all the persistent messages. Just big enough to hold the U.O.W.s.
(For example, create a default QM which gives you about 5 MB of logs. Then go ahead and put gigs and gigs of persistent messages into the queues) |
Agree with circular logging. Does that apply too for linear logging???
and a queue with 9 Terabyte in size? that's still a DATABASE...
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| jefflowrey |
| Posted: Thu Jan 31, 2008 6:09 pm Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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| fjb_saper wrote: |
| Agree with circular logging. Does that apply too for linear logging??? |
Yes.
The log space is only for active transactions.
The available space on the file system, however...
| fjb_saper wrote: |
| and a queue with 9 Terabyte in size? that's still a DATABASE... |
Nah, just a really paranoid infrastructure engineer.
EDIT: Except, of course, q files in v5.3 can only go to 2 gig.
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| fjb_saper |
| Posted: Thu Jan 31, 2008 7:04 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
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Location: LI,NY
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| jefflowrey wrote: |
| fjb_saper wrote: |
| Agree with circular logging. Does that apply too for linear logging??? |
Yes.
The log space is only for active transactions. |
So this is where the big diff lies [needed for qmgr restart - needed for media recovery]!
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| jefflowrey |
| Posted: Thu Jan 31, 2008 7:49 pm Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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| fjb_saper wrote: |
| So this is where the big diff lies [needed for qmgr restart - needed for media recovery]! |
But that diff is entirely controllable based on how frequently you run rcdmqimg.
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| PeterPotkay |
| Posted: Thu Jan 31, 2008 11:28 pm Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7723
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| jefflowrey wrote: |
| EDIT: Except, of course, q files in v5.3 can only go to 2 gig. |
That 2 gig q file limitation only exits on Unix systems if the O/S'es largefiles option has not been turned on.
Windows does not have this limitation either way. Yay! Score one for Windows. 
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Peter Potkay
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| Vitor |
| Posted: Fri Feb 01, 2008 2:03 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| PeterPotkay wrote: |
| Windows does not have this limitation either way. Yay! Score one for Windows. |
Just the one. This still puts it way, way down the field. 
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| fjb_saper |
| Posted: Fri Feb 01, 2008 4:23 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20767
Location: LI,NY
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| jefflowrey wrote: |
| fjb_saper wrote: |
| So this is where the big diff lies [needed for qmgr restart - needed for media recovery]! |
But that diff is entirely controllable based on how frequently you run rcdmqimg.
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Sure but in this case you still end up with 9 Terabyte of data if you want to keep the media recovery...
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| ChrisW |
| Posted: Tue Feb 05, 2008 7:26 am Post subject: |
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Voyager
Joined: 20 May 2001
Posts: 78
Location: UK
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| Actually around 18 terabytes of log space for media recovery - the old image will have to exist until the new one is there. |
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