IDS Forum

RE: Checkpoint duration too long sometimes--no fixed pattern

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Date:

Vineet,

May be you're hitting a bug. I bet that this is happening due to some
adhoc report or query(ies). Longtime back at my work I place, I had a
similar situation. Found out that some of the reports were run, with
sqls creating temp tables with log. I went thru all the sqls and
changed temp table creation to be "with no log". That subsided the
problem. During high checkpoint time, you could trace the sql with
"onstat -g sql" and "onstat -g ses <sql pid>" would give you defaulting
report/application. And I am sure you know that it could be better to
reduce checkpoint interval period to 5/6 minutes.

In my system, I monitor errorlog file for checkpoints for more than 6
seconds. If it does occur then I page myself so that I can quickly see
what is going on.

hope this helps,

Vivek

> -----Original Message-----
> From: vin.us [mailto:vin_us@yahoo.com]
> Sent: Wednesday, April 30, 2003 1:52 PM
> To: ids; forum.subscriber; vin.us
> Subject: Checkpoint duration too long sometimes--no fixed
> pattern [1054]
>
>
>
> Environment:
>
>
> Informix Dynamic Server 7.31 UD2 R1
>
> HP-UX 11.0
>
> As you can see below
>
> 10:44:50 Checkpoint Completed: duration was 0
> seconds.
> 10:59:59 Checkpoint Completed: duration was 0
> seconds.
> 11:15:08 Checkpoint Completed: duration was 0
> seconds.
> 11:30:17 Checkpoint Completed: duration was 0
> seconds.
> 11:45:26 Checkpoint Completed: duration was 0
> seconds.
> 12:00:53 Checkpoint Completed: duration was 19
> seconds.
> 12:16:02 Checkpoint Completed: duration was 0
> seconds.
> 12:31:34 Checkpoint Completed: duration was 23
> seconds.
> 12:46:44 Checkpoint Completed: duration was 0
> seconds.
> 13:01:54 Checkpoint Completed: duration was 1
> seconds.
> 13:17:05 Checkpoint Completed: duration was 2
> seconds.
> 13:32:15 Checkpoint Completed: duration was 0
> seconds.
> 13:47:24 Checkpoint Completed: duration was 0
> seconds.
> 14:02:33 Checkpoint Completed: duration was 1
> seconds.
> 14:17:43 Checkpoint Completed: duration was 1
> seconds.
> 14:32:54 Checkpoint Completed: duration was 0
> seconds.
> 14:48:03 Checkpoint Completed: duration was 0
> seconds.
> 15:03:13 Checkpoint Completed: duration was 2
> seconds.
> 15:18:23 Checkpoint Completed: duration was 0
> seconds.
> 15:35:08 Checkpoint Completed: duration was 97
> seconds.
>
> we have at times checkpoints of duration more than a
> minute. This is totally unacceptable in production
> environment.
>
> We are unable to diagnose a pattern for this. It could
> happen at any time throughout the day. I don't have
> any clues where to look for and what could be the
> possible reason for this behaviour.
> Here are the related checkpoint parameters which we
> have set in our environment for your reference.
>
> MULTIPROCESSOR 1 # 0 for
> single-processor, 1 for multi-processor
> NUMCPUVPS 5 # Number of user (cpu)
> vps
> SINGLE_CPU_VP 0
>
>
> BUFFERS 500000
>
> CLEANERS 128
>
> CKPTINTVL 900
>
> LRUS 128
>
> LRU_MAX_DIRTY 2
>
> LRU_MIN_DIRTY 1
>
>
> Also interesting most of the times we have 0 LRU
> writes in the system and only writes happen are the
> chunkwrites at the time of checkpoint.
>
> Fg Writes LRU Writes Chunk Writes
> 0 2 14620
>
> Are we hitting some kind of bug? Or doing something
> wrong.
>
> Any help on this is highly appreciated.
>
> Do let me know if you need more information.
>
> Thanks and regards,
>
> Vineet
>
>
>
>
>
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Messages In This Thread

• Checkpoint duration too long sometimes--no fixed pattern
  Vineet Mehrotra -- Wednesday, 30 April 2003, at 4:51 p.m.
  • RE: Checkpoint duration too long sometimes--no fixed pattern
    vivek.chaudhary@st.com -- Wednesday, 30 April 2003, at 5:28 p.m.
  • Re: Checkpoint duration too long sometimes--no fixed pattern
    Vineet Mehrotra -- Wednesday, 30 April 2003, at 5:47 p.m.

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