IDS Forum

Re: LOGBUFF Setting

Posted By: John Miller iii
Date: Wednesday, 25 January 2017, at 10:59 a.m.

In Response To: Re: LOGBUFF Setting (Keith Simmons)

I think you might be mixing up LOGBUF and LOGSIZE. The logical log buffer
is a buffer
that can group logical log records together before writing them to disk.
If you have
unbuffered logging then every commit from an unbuffered logging database
will
write this buffer to disk and not allow the commit to continue until the
write
has completed. So the data is always on disk for every commit.

The warning you are receiving has to do with the size of a single log
record. You can
examine your logs with onlog and look at the size column. Logical Log
records must
fit into a single buffer and in your case you have a record which is larger
than 128K.

If you are not hurting for 1MB of memory I would suggest 512KB. There are
three buffers
so this means you will be using 1.5 MB of memory for the log buffers.
There will be 0
chance of additional loss of data by expanding these buffers, only a chance
of wasting memory.
If these buffers are undersized then there will be allot of extra I/O done.
So increasing
the size in your case my reduce the I/O to the disk the logical logs reside
on.

John F. Miller III
miller3@us.ibm.com

ids-bounces@iiug.org wrote on 01/25/2017 07:38:50 AM:

> From: "Keith Simmons" <smiley73@gmail.com>
> To: ids@iiug.org
> Date: 01/25/2017 07:39 AM
> Subject: Re: LOGBUFF Setting [38561]
> Sent by: ids-bounces@iiug.org
>
> Dave
>
> Rule of thumb is that it should be large enough for the system
throughput,
> but not so large that you could not afford to lose that data in the case
of
> a catastrophic server event and you had to recover and roll-forward log
> files. I too have a busy OLTP system and have LOGBUFF set to 256. You
could
> try 130 but I would suggest a bit bigger and would try 192 (binary-type
> sizes always work better :-) ).
>
> Keith
>
> On 25 January 2017 at 14:40, Informix DBA <in4mixdba@gmail.com> wrote:
>
> > Hi,
> >
> > We are running Informix 11.70.FC7W2 on Solaris 11. We have been getting

> > the following message in the online.log.
> >
> > 01/24/17 15:24:55 Checkpoint log record may not fit into the logical
log
> > buffer.
> > Recommended minimum value for LOGBUFF is 130.
> >
> > We currently have LOGBUFF set to 128 and RTO=5FSERVER=5FRESTART 0. We a=
re
> > running a busy OLTP system with unbuffered DB's.
> >
> > What is the recommended setting for LOGBUFF and how to you calculate
it?
> >
> > Thank You,
> >
> > --Dave
> >
> > --f403045ea5243e29980546ec366e
> >
> >
> > ************************************************************
> > *******************
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> >
> >
>
> --001a1145ac32c8f2eb0546ed0650
>
>
>
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****

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Messages In This Thread

• LOGBUFF Setting
  Informix DBA -- Wednesday, 25 January 2017, at 9:40 a.m.
  • Re: LOGBUFF Setting
    Andreas Legner -- Wednesday, 25 January 2017, at 10:34 a.m.
  • Re: LOGBUFF Setting
    Keith Simmons -- Wednesday, 25 January 2017, at 10:38 a.m.
    • Re: LOGBUFF Setting
      John Miller iii -- Wednesday, 25 January 2017, at 10:59 a.m.
      • Re: LOGBUFF Setting
        Informix DBA -- Wednesday, 25 January 2017, at 3:23 p.m.
      • Re: LOGBUFF Setting
        Fernando Nunes -- Wednesday, 25 January 2017, at 8:12 p.m.
  • Re: LOGBUFF Setting
    Madison Pruet -- Wednesday, 25 January 2017, at 11:09 a.m.

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