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| dgolding |
 Posted: Thu Jul 31, 2008 2:57 am Post subject: IBM finally admits linear logging sucks |
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Yatiri
Joined: 16 May 2001
Posts: 668
Location: Switzerland
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From the MQ best practices page (Link here):
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| A common misconception in the MQ community is that linear logging is more appropriate for production-level systems. In addition to the circular logging benefits, linear logging only incrementally provides object-recovery abilities, and it comes with the cost of regular maintenance to prevent file systems from filling. If the MS03 SupportPac is set up to run regularly, a copy of objects can be replayed from those scripts, minimizing the need for linear logging. Circular-logging queue managers require less maintenance and have less risk of crashing due to using up disk space. |
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| Mr Butcher |
| Posted: Thu Jul 31, 2008 4:27 am Post subject: |
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Padawan
Joined: 23 May 2005
Posts: 1716
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no linear logging, no media recovery. what really s*cks always depends on what you need or not.
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Regards, Butcher |
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| fjb_saper |
| Posted: Thu Jul 31, 2008 6:47 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| Mr Butcher wrote: |
| no linear logging, no media recovery. what really s*cks always depends on what you need or not. |
I believe the question here is can you afford to loose all the messages on a damaged queue, or does your app mandate you to recover the object...
Remember that loosing object recovery from media (linear logging) breaks the assured delivery paradigm.
Enjoy 
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| mlr |
| Posted: Thu Jul 31, 2008 12:53 pm Post subject: |
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Novice
Joined: 29 Jun 2008
Posts: 13
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i think that should be lose...
loose is the opposite of tight
lose is the opposite of find
why is this such a common error in postings?
others are: teh (typo), could of for could have (illiterate)
any more for any more? |
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| bruce2359 |
| Posted: Thu Jul 31, 2008 1:23 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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Skipping over the issue of loose vs lose...[EDIT] vs. Lucy, I'm home!.
Media recovery seems like a mixed blessing. I ponder whether logging messages to the log AND recording media images to the log doesn't put all our mission-critical message eggs in one single-point-of-failure basket.
As an example: I'm logging 100meg messages; I then record the queue image to the log, Voila! (pronounced wah-lah) lots of log segments.
For clients (people, not applications), I suggest that for messages that reside in queues for batch processing, perhaps writing an application that browses the messages and writes them to a sequential file (or whatever) might be a better career-saving methodology.
Did I offer any language correction opportunities?
_________________
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.
Last edited by bruce2359 on Thu Jul 31, 2008 1:49 pm; edited 1 time in total |
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| mqjeff |
| Posted: Thu Jul 31, 2008 1:46 pm Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| I never like to contemplate what happens if SYSTEM.CLUSTER.REPOSITORY.QUEUE gets media damage. |
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| PeterPotkay |
| Posted: Tue Aug 05, 2008 11:23 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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Nowadays (storage technology gets better, average MQ admin skill going down), I wonder what's more likely:
Media failure, or linear logs not maintained properly.
_________________
Peter Potkay
Keep Calm and MQ On |
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| Michael Dag |
| Posted: Tue Aug 05, 2008 11:41 am Post subject: |
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Jedi Knight
Joined: 13 Jun 2002
Posts: 2607
Location: The Netherlands (Amsterdam)
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| PeterPotkay wrote: |
Nowadays (storage technology gets better, average MQ admin skill going down), I wonder what's more likely:
Media failure, or linear logs not maintained properly. |
I experienced some damaged objects lately at a new customer location.
Fortunately the data could be retrieved from another place (always a good option!!!  ),
turns out large file support was not on for the file system and every now and then the Q file got corrupted... 
It should be fixed now, but it does make you panic for a moment... as with
circular logs there is nothing you can do to recover the object's data....
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Michael
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| mqjeff |
| Posted: Tue Aug 05, 2008 11:44 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| Michael Dag wrote: |
| PeterPotkay wrote: |
Nowadays (storage technology gets better, average MQ admin skill going down), I wonder what's more likely:
Media failure, or linear logs not maintained properly. |
I experienced some damaged objects lately at a new customer location.
Fortunately the data could be retrieved from another place (always a good option!!! ),
turns out large file support was not on for the file system and every now and then the Q file got corrupted...
It should be fixed now, but it does make you panic for a moment... as with
circular logs there is nothing you can do to recover the object's data.... |
Yes... Clearly Peter forgot to account for "average storage admin skill going down"...  |
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| bruce2359 |
| Posted: Tue Aug 05, 2008 11:46 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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In a real world, the likelihood of media failure OR a runaway application filling the logs or linear logs not maintained properly or average MQ admin skill going down, are low, unless it happens to you; then the likelihood is very high.
_________________
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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| PeterPotkay |
| Posted: Tue Aug 05, 2008 11:51 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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Touché Jeff 
Although if the SAN guy ain't got no clue, I doubt its just 1 queue getting damaged. The whole QM is gone.
No storage admins, good or otherwise, are involved if you are running on local mirrored disks, though.
_________________
Peter Potkay
Keep Calm and MQ On |
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| PeterPotkay |
| Posted: Tue Aug 05, 2008 11:59 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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| bruce2359 wrote: |
| In a real world, the likelihood of media failure OR a runaway application filling the logs or linear logs not maintained properly or average MQ admin skill going down, are low, unless it happens to you; then the likelihood is very high. |
The most oddball, extremely rare problem is a big deal when it hits you.
You gotta weigh all the pros and cons when deciding between logging types, and don't forget to factor in technology moving forward.
People tend to be passionate about this topic in general.
_________________
Peter Potkay
Keep Calm and MQ On |
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| falconX |
| Posted: Tue Aug 05, 2008 12:27 pm Post subject: |
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Novice
Joined: 04 Sep 2007
Posts: 18
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| PeterPotkay wrote: |
Nowadays (storage technology gets better, average MQ admin skill going down), I wonder what's more likely:
Media failure, or linear logs not maintained properly. |
we are still wondring which is more likely  |
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| Michael Dag |
| Posted: Tue Aug 05, 2008 12:58 pm Post subject: |
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Jedi Knight
Joined: 13 Jun 2002
Posts: 2607
Location: The Netherlands (Amsterdam)
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| PeterPotkay wrote: |
| People tend to be passionate about this topic in general. |
holy wars? 
I gave up and just deal with it the way it is.
I try to keep things as simple as possible (circular) and point out the 'risks' ...
this last incident blindsided me as I was just in for a day and the Q file got corrupted (uh oh...  )
Luck was on my side and the data was also somewhere else... but it could have been different...
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Michael
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| bruce2359 |
| Posted: Tue Aug 05, 2008 3:36 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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| Quote: |
| I try to keep things as simple as possible (circular) and point out the 'risks' |
If something is inevitable or likely, warning someone ahead of time doesn't keep them from complaining bitterly when it occurs; or fingering you for an ineffective warning.
I usually look to what I can manage, and what I can't. I can't manage how programmers write their code; but I can manage (buy, write) some automation that will archive inactive log segments as they occur.
_________________
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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