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| issac |
 Posted: Fri May 17, 2013 12:42 am Post subject: Does it matter for logs to be small? |
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Disciple
Joined: 02 Oct 2008
Posts: 158
Location: Shanghai
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Our production QMGR was created with log size set to 1024, and 3 primary logs and 2 secondary logs, which makes the log space estimated to 4M*5=20M. We have been constantly having log space full stuations and are considering enlarge them.
If we don't recreate the QMGR, we plan to have 180 primary logs and 60 secondary logs, which totals (180+60)*4M=240*4M=960M.
Otherwise we could re-create the QMGR setting log size to 64M, 10 primary logs and 5 secondary logs, totals 960M as well.
Does it make significant difference to have a lot of small logs just to avoid recreating the QMGR?
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| zpat |
| Posted: Fri May 17, 2013 1:32 am Post subject: |
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Jedi Council
Joined: 19 May 2001
Posts: 5866
Location: UK
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IBM need to change the defaults - they are simply too small and it's annoying (if someone forgets to set them at installation time).
I believe you will get better performance with larger size values in fewer files. |
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| exerk |
| Posted: Sat May 18, 2013 2:07 am Post subject: |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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| zpat wrote: |
| IBM need to change the defaults - they are simply too small and it's annoying (if someone forgets to set them at installation time)... |
Site standards, documentation, automation, and peer review should ensure that the mqs.ini file is edited to ensure correct log numbers and size are specified, or made irrelevant.
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| zpat |
| Posted: Sat May 18, 2013 3:16 am Post subject: |
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Jedi Council
Joined: 19 May 2001
Posts: 5866
Location: UK
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Really, that never occurred to me.
Nevertheless not everyone is as perfect as you or me and I have come across queue managers installed with the defaults.
Hence the problem posted above - it will happen due to Sod's law.
Defaults are very, very important to make sensible because beginners will assume they are suitable for most purposes.
I waste a lot of time chasing developers who don't use MQSTR or MQRFH2 as their MQMD format (the default is blank), thanks to that unhelpful default. |
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| PeterPotkay |
| Posted: Sat May 18, 2013 3:30 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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IBM finally bumped up the default size of the MQ error logs a few years ago from 256K, so maybe there's hope for the transactional log defaults to become realistic in the future too.
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Peter Potkay
Keep Calm and MQ On |
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| exerk |
| Posted: Sat May 18, 2013 5:11 am Post subject: |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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| zpat wrote: |
| Really, that never occurred to me. |
Unlike Sheldon I do get sarcasm... 
| zpat wrote: |
| Nevertheless not everyone is as perfect as you or me and I have come across queue managers installed with the defaults. |
Thank you for the vote of confidence, but I'm anything but perfect...
| zpat wrote: |
| Hence the problem posted above - it will happen due to Sod's law. |
Indeed, but only likely on a manual install, which processes and procedures should make all but impossible...
| zpat wrote: |
| Defaults are very, very important to make sensible because beginners will assume they are suitable for most purposes. |
Agreed. The problem, from a vendors point of view, is just how much hand-holding to do...
| zpat wrote: |
| I waste a lot of time chasing developers who don't use MQSTR or MQRFH2 as their MQMD format (the default is blank), thanks to that unhelpful default. |
Now that one I fully sympathise with, which is why 'coding' standards should to be included within any discussion of WMQ standards in a using organisation.
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It's puzzling, I don't think I've ever seen anything quite like this before...and it's hard to soar like an eagle when you're surrounded by turkeys. |
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| bruce2359 |
| Posted: Sat May 18, 2013 5:23 am Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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| zpat wrote: |
| IBM need to change the defaults - they are simply too small ... |
Default log size is more than adequate for initial installation and product verification (IVP).
And, yes, I wholeheartedly agree that the defaults are too small for QA and Production. But, really, what size would you have the defaults set at??
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| zpat |
| Posted: Sat May 18, 2013 8:51 am Post subject: |
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Jedi Council
Joined: 19 May 2001
Posts: 5866
Location: UK
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Since those values were chosen, the average size of disks has increased massively - they should at least keep some pace.
They should increase the logpagesize because then the secondary log files would actually be of some use - and they will only be allocated if needed.
I have no problem with keeping the primary log file number low - just don't make the size so pathetic. |
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| smdavies99 |
| Posted: Sat May 18, 2013 9:35 am Post subject: |
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Jedi Council
Joined: 10 Feb 2003
Posts: 6076
Location: Somewhere over the Rainbow this side of Never-never land.
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| zpat wrote: |
| just don't make the size so pathetic. |
 
Or at least a way to make the default size something more reasonable.
I have nearly lost count of the number of QMGRS I have had to rebuild because the logfile size was too small.
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WMQ User since 1999
MQSI/WBI/WMB/'Thingy' User since 2002
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Every time you reinvent the wheel the more square it gets (anon). If in doubt think and investigate before you ask silly questions. |
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| bruce2359 |
| Posted: Sat May 18, 2013 9:55 am Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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Reasonable for who? How about setting mqs.ini defaults to an invalid value. Next crtmqm attempt will fail, rather than creating irrationally sized logs.
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ב''ה
Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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| exerk |
| Posted: Sat May 18, 2013 10:48 am Post subject: |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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| bruce2359 wrote: |
| Reasonable for who?... |
Precisely the issue - what's good for one site is anathema to another.
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It's puzzling, I don't think I've ever seen anything quite like this before...and it's hard to soar like an eagle when you're surrounded by turkeys. |
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| bruce2359 |
| Posted: Sat May 18, 2013 12:54 pm Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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| exerk wrote: |
| bruce2359 wrote: |
| Reasonable for who?... |
Precisely the issue - what's good for one site is anathema to another. |
I take meds for that.
_________________
I like deadlines. I like to wave as they pass by.
ב''ה
Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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| mvic |
| Posted: Sat May 18, 2013 1:25 pm Post subject: |
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Jedi
Joined: 09 Mar 2004
Posts: 2080
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| zpat wrote: |
| IBM need to change the defaults - they are simply too small and it's annoying (if someone forgets to set them at installation time). |
Probably someone at IBM heard you, a few years ago. 
There was a change in the defaults. See http://publib.boulder.ibm.com/infocenter/wmqv7/v7r0/topic/com.ibm.mq.amqzag.doc/fa12570_.htm
"The default number of log file pages is 4096, giving a log file size of 16 MB."
So a default setting of 5 x 16 = 80 MB maximum active log. Probably keeping pace with modern needs? (though not necessarily modern disk capacities as in your other post, but I'm not clear what relevance that has. Data writing *rate* has more impact on log store size choice than disk max capacity). |
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