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| How fast is my MQ log being consummed ? |
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| KIT_INC |
 Posted: Mon Oct 21, 2013 9:00 am Post subject: How fast is my MQ log being consummed ? |
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Knight
Joined: 25 Aug 2006
Posts: 589
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We are using MQ v7.0.1 on Linux 64 bit and doing circular logging. We are interested in knowing how fast is the MQ log being consummed. We know that the admin manual has the formula for estimating the log usage.
We like to get some advice on how to do the real usage estimate base on data from the real environment.
Our MQ logs are default size of 16M and I always see on 3 active logs.I am not sure if secondary log is ever used.
an ls -l of my log file shows
-rw-rw---- 1 mqm mqm 16785408 2013-10-21 08:48 S0000000.LOG
-rw-rw---- 1 mqm mqm 16785408 2013-10-21 08:55 S0000001.LOG
-rw-rw---- 1 mqm mqm 16785408 2013-10-21 08:35 S0000002.LOG
If the time is the last mofication time to the file. The time between log...2 and log...0 is 13 minutes and the time between log...0 to log...1 is 7 minutes. Log...1 has the latest time time, so it is the current log and is not filled yet. I can have a rough estimate saying that around the time of the display, MQ using consumming 16M of log space in 13 minutes. We understand this kind of estimate is not good enough for any planning. But what we need is just a rough idea at this time.
A more acccurate way I think may be using data from dmping the MQ log, We did that and we have trouble finding any time stamps inthe dmpmqlog output
LOG FILE HEADER
***************
counter1 . . . : 34309 counter2 . . . : 65535
FormatVersion . : 4 StrucId . . . . : 'HLFH'
logactive . . . : 3 loginactive . . : 2
logsize . . . . : 4096 pages
baselsn . . . . : <0:219:49408:0>
nextlsn . . . . : <0:219:49920:59820>
lowtranlsn . . : <0:219:49564:58647>
minbufflsn . . : <0:219:49565:49562>
headlsn . . . . : <0:219:49564:58647>
taillsn . . . . : <0:219:49920:59819>
hflag1 . . . . : 0
-> CIRCULAR
HeadExtentID . : 0 LastEID . . . . : 1382303670
LogId . . . . . : 1328115161
FirstArchNum . : 4294967295 LastArchNum . . : 4294967295
nextArcFile . . : 4294967295
FileCount . . . : 3
Files . . . . . : 0, 1, 2
LastCId . . . . : 4294967295 softmax . . . . : 4294967295
I can see the
headlsn . . . . : <0:219:49564:58647>
taillsn . . . . : <0:219:49920:59819>
But I don't know what these number means and I don't know where to get the timestamps. So that I can tell how many log records were written within the time. |
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| JosephGramig |
| Posted: Mon Oct 21, 2013 10:33 am Post subject: |
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Grand Master
Joined: 09 Feb 2006
Posts: 1244
Location: Gold Coast of Florida, USA
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If you don't know anything to calculate the size of your Log File Pages, then pick 16384 which is 1/8th the max size. The default of 4098 is not likely going to work well (eventually) on a production Qmgr.
Of course, I'm assuming you are going to stick with circular logs. Note that you cannot change LogFilePages or the type of transaction logging after the Qmgr has been created. If you want to change it, then you must saveqmgr and authorizations and unload any queues where you want to keep the msgs. Recreate it as you actually want it. You may need to reset some channels. If you were using clustering, you should remove the Qmgr from each cluster first before deleting the Qmgr (otherwise you will need to force remove the old Qmgr by QMID). |
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| KIT_INC |
| Posted: Mon Oct 21, 2013 10:54 am Post subject: |
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Knight
Joined: 25 Aug 2006
Posts: 589
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| No we are not looking at making any changes unless the results indicate a need. Someone did the planning and create the Qmgr using the defaults We are just being asked if we can tell how fast is the allocated log space is comsumed. That why I tried to use the file time stamp as an initial indicator and see if the dmpmqlog will give us more accurate results. |
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| bruce2359 |
| Posted: Mon Oct 21, 2013 1:50 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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Arriving at a well-configured logging environment is well documented. Search google for 'calculating the size of logs', or go here: http://publib.boulder.ibm.com/infocenter/wmqv6/v6r0/index.jsp?topic=%2Fcom.ibm.mq.amqzag.doc%2Ffa14560_.htm
You or your developers will need to know how many transactions, duration and maximum transaction length, size of messages that comprise transactions, and so on.
Other than calculating, you can make a presumption that your current log size is adequate if current transaction activity is representative of your average and peak transaction activity. So, if each log lasts 5 minutes or so now, before being reused, and you have 3 primary and 2 secondary, you likely have sufficient logs. Growth over time (new apps, new users, etc.) may change this.
I'd take the time to do the calculations. Sysadmins should understand current and future applications, and their impact on all system resources.
_________________
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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| gbaddeley |
| Posted: Mon Oct 21, 2013 2:18 pm Post subject: Re: How fast is my MQ log being consummed ? |
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Jedi Knight
Joined: 25 Mar 2003
Posts: 2538
Location: Melbourne, Australia
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| KIT_INC wrote: |
We are using MQ v7.0.1 on Linux 64 bit and doing circular logging. We are interested in knowing how fast is the MQ log being consummed. We know that the admin manual has the formula for estimating the log usage. We like to get some advice on how to do the real usage estimate base on data from the real environment.
Our MQ logs are default size of 16M and I always see on 3 active logs.I am not sure if secondary log is ever used.
an ls -l of my log file shows
-rw-rw---- 1 mqm mqm 16785408 2013-10-21 08:48 S0000000.LOG
-rw-rw---- 1 mqm mqm 16785408 2013-10-21 08:55 S0000001.LOG
-rw-rw---- 1 mqm mqm 16785408 2013-10-21 08:35 S0000002.LOG
If the time is the last mofication time to the file. The time between log...2 and log...0 is 13 minutes and the time between log...0 to log...1 is 7 minutes. Log...1 has the latest time time, so it is the current log and is not filled yet. I can have a rough estimate saying that around the time of the display, MQ using consumming 16M of log space in 13 minutes. We understand this kind of estimate is not good enough for any planning. But what we need is just a rough idea at this time. |
This estimate can be good enough for planning. Your logs are cycling fairly quickly. To avoid running out of log space, make sure you don't have any long running UOW that might exceed this time. 3 primary logs is a low number for production. If you have the disk space, go for 16, 64 or even a higher number, and use larger log files 32MB or 64MB. Disk space is cheap. Allow for the same number of secondary log files. eg. 64 prim + 64 sec * 32 meg = 4 GB space required on /var/mqm/log file system.
It is very hard to come up with accurate figures for log sizes, application behaviour and message volume and be unpredicable.
_________________
Glenn |
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| KIT_INC |
| Posted: Mon Oct 21, 2013 3:02 pm Post subject: |
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Knight
Joined: 25 Aug 2006
Posts: 589
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Thanks gbaddeley for confirming that estimate based on file time can be good enough for planning.
I was actually quite surprised that there is no time stamps for each log record so that I can tell how many log records are in a log file and the start and the end time of the use of the file. |
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