Checkpoint Frequency too high

John Arbogast

Checkpoint Frequency too high
I agree 400 per hour is way out of line!! We shoot
for 4 to 6 per hour during our nightly batch flows.
During (relative) quiet times we somtimes go over an
hour without a checkpoint.

Insert your favorite disclaimer here.

Happy Holidays!
John Arbogast.


--- craig patton <[login to unmask email]> wrote:
> Chris,
>
> First, 400 checkpoints per hour is extremely high!
> Definitely raise your
> LOGLOAD parameter so that you take about 4
> checkpoints per hour. Keep in
> mind that while DB2 is taking a checkpoint, NO OTHER
> ACTIVITY can take
> place. Checkpoints are very short in duration, but
> at 400 per hour, your
> system is quite degraded as you are performing 1
> checkpoint about every 9
> seconds....Are you positive about the 400 per hour
> or is that for the whole
> reporting period?? 400 is about right for a 24 hour
> time frame. If it
> really is 400/hour, I would take that LOAGLOAD And
> increase it to 500,000
> and then check your checkpoint frequency and adjust
> from there.
>
> HTH,
> Craig Patton
> DB2 DBA
> Patton Research Group, Inc.
>
>
> >From: "Hayes, Chris" <[login to unmask email]>
> >Reply-To: DB2 Data Base Discussion List
> <[login to unmask email]>
> >To: [login to unmask email]
> >Date: Tue, 21 Dec 1999 11:04:55 -0500
> >
> >While looking through some reports, I noticed that
> one of our production
> >DB2
> >subsystems is checkpointing over 400 times an hour
> during certain times. I
> >checked our checkpoint frequency parameter and it
> is set at 50,000. IBM
> >recommends using 25,000 to 500,000 in their
> Installation Guide. Am I
> >correct in thinking that 400 times an hour is
> excessive? Should I be
> >concerned about raising the threshold? IBM's
> Installation Guide mentions
> >that start-up time may be excessive (over 30
> minutes) if you specify a
> >value
> >over 300,000 and you terminate DB2 without a
> quiesce. Is this a real
> >concern or should DB2 always be stopped with a
> quiesce?
> >
> >
> >To change your subscription options or to cancel
> your subscription visit
> >the DB2-L webpage at http://www.ryci.com/db2-l. The
> owners of the list can
> >
>
>
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John Arbogast

Re: Checkpoint Frequency too high
(in response to John Arbogast)
Yes they do, but they are marked for reuse.

--- "Hayes, Chris" <[login to unmask email]> wrote:
> Craig - Thanks for your prompt response.
>
> The report tool I am using breaks up various system
> statistics by the hour.
> The checkpoint frequency numbers range between 0 and
> 561 (the latest high
> water mark) with the highest occurring between 22:00
> and 01:00 when we do a
> lot of batch updates. Most of the time, the number
> is under 10 per hour. I
> will talk with the system's people about raising
> this parameter.
>
> Another question occurred to me during this
> analysis. When DB2 writes the
> updated pages during a checkpoint, do these pages
> remain in the buffer?
>
> -----Original Message-----
> From: craig patton [mailto:[login to unmask email]
> Sent: Tuesday, December 21, 1999 11:39 AM
> To: [login to unmask email]
> Subject: Re: Checkpoint Frequency to high
>
>
> Chris,
>
> First, 400 checkpoints per hour is extremely high!
> Definitely raise your
> LOGLOAD parameter so that you take about 4
> checkpoints per hour. Keep in
> mind that while DB2 is taking a checkpoint, NO OTHER
> ACTIVITY can take
> place. Checkpoints are very short in duration, but
> at 400 per hour, your
> system is quite degraded as you are performing 1
> checkpoint about every 9
> seconds....Are you positive about the 400 per hour
> or is that for the whole
> reporting period?? 400 is about right for a 24 hour
> time frame. If it
> really is 400/hour, I would take that LOAGLOAD And
> increase it to 500,000
> and then check your checkpoint frequency and adjust
> from there.
>
> HTH,
> Craig Patton
> DB2 DBA
> Patton Research Group, Inc.
>
>
> >From: "Hayes, Chris" <[login to unmask email]>
> >Reply-To: DB2 Data Base Discussion List
> <[login to unmask email]>
> >To: [login to unmask email]
> >Date: Tue, 21 Dec 1999 11:04:55 -0500
> >
> >While looking through some reports, I noticed that
> one of our production
> >DB2
> >subsystems is checkpointing over 400 times an hour
> during certain times. I
> >checked our checkpoint frequency parameter and it
> is set at 50,000. IBM
> >recommends using 25,000 to 500,000 in their
> Installation Guide. Am I
> >correct in thinking that 400 times an hour is
> excessive? Should I be
> >concerned about raising the threshold? IBM's
> Installation Guide mentions
> >that start-up time may be excessive (over 30
> minutes) if you specify a
> >value
> >over 300,000 and you terminate DB2 without a
> quiesce. Is this a real
> >concern or should DB2 always be stopped with a
> quiesce?
> >
> >
> >To change your subscription options or to cancel
> your subscription visit
> >the DB2-L webpage at http://www.ryci.com/db2-l. The
> owners of the list can
> >
>
>
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>
>
> To change your subscription options or to cancel
> your subscription visit the
> DB2-L webpage at http://www.ryci.com/db2-l. The
> owners of the list can be
>
>
>
> To change your subscription options or to cancel
> your subscription visit the DB2-L webpage at
> http://www.ryci.com/db2-l. The owners of the list
> can
>

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HARBRY ARIZA

Re: Checkpoint Frequency to high
(in response to John Arbogast)
Chris:

Here in our shop we have Activity monitor (AM) and Opertune (OP)
(BMC products). I think these products are amazing because some critical
activities could be maiden easily count on these products as part of your
shop. For example , the LOGLOAD parameter was setup 4000 , it seems to be
short enough to kill your db2 but not because using AM and OP we turn on an
exeption that can increase this parameter if the frecuency of checkpoint is
too high and when the db2 activity become normal that value is reset
automatically. If in your shop you can afford these products it would be
great for you and your work as db2 system programmer.

I hope it helps.



>>From: "Hayes, Chris" <[login to unmask email]>
>>Reply-To: DB2 Data Base Discussion List <[login to unmask email]>
>>To: [login to unmask email]
>>Date: Tue, 21 Dec 1999 11:04:55 -0500
>>
>>While looking through some reports, I noticed that one of our production
>>DB2
>>subsystems is checkpointing over 400 times an hour during certain times.
>>I
>>checked our checkpoint frequency parameter and it is set at 50,000. IBM
>>recommends using 25,000 to 500,000 in their Installation Guide. Am I
>>correct in thinking that 400 times an hour is excessive? Should I be
>>concerned about raising the threshold? IBM's Installation Guide mentions
>>that start-up time may be excessive (over 30 minutes) if you specify a
>>value
>>over 300,000 and you terminate DB2 without a quiesce. Is this a real
>>concern or should DB2 always be stopped with a quiesce?
>>
>>
>>
>>
>>
>
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>
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