Good stuff, thanks!
T
-----Original Message-----
From: Alex Levy [mailto:db2udbdba-ezmlmshield-x77940949.[Email address protected]
Sent: Thursday, May 01, 2008 9:11 AM
To: LazyDBA Discussion
Subject: RE: History File v8.2
Hi Terry,
Yes, the reason for your question now makes very good sense! and indeed you
have answered your own question:
Anyone else please jump in, but a basic mount point design principle for
database layout is to keep each one of these in their own separate
filesystems: application data, system catalog tables, temporary data, logs,
archive logs, database and system directories, the instance home and db2dump
directories. Anything that can end up in a bufferpool (i.e. table data)
should benefit from CIO, flat files won't. Assuming your RHF is also pruned
regularly, I'm pretty sure relocating your tablespaces and altering the
filesystem properties will solve your issue. Remember CIO can be turned on
at tablespace level, so there is no need to place system files in JFS rather
than JFS2.
HTH
Alex
-----Original Message-----
From: Terry Gilbert
[mailto:db2udbdba-ezmlmshield-x39734805.[Email address protected]
Sent: 1 May 2008 13:15
To: LazyDBA Discussion
Subject: RE: History File v8.2
Caveat - new to this so some of my terms may be wrong, my arguments and
ideas may be whacked. (admittedly that may have nothing to do with me being
new to db2;-)
We have a lot of bulkloads (1k's to 10k's or rows) happening concurrently
and they are getting blocked waiting for history file access. The
filesystem is mounted CIO so the access to the history file is not
benefiting from a system file cache. We have had better performance with
CIO generally, I believe that's typical but I would love to hear of any
differing experiences .
So we thought first that maybe we don't need the history file but you've
answered that (thank you) secondly we thought to move the history file on
to another JFS filesystem but you've answered that too, thanks again :-)
Sounds like it was just unfortunate that the tablespace container for the
application data was placed in the same filesystem, and we should possibly
rebuiild this instance so that we can keep some of the db2 stuff using JFS
while our application data ends up using CIO filesystems.
Does that make sense?
Cheers
T
-----Original Message-----
From: Alex Levy [mailto:db2udbdba-ezmlmshield-x77382017.[Email address
protected]
Sent: Thursday, May 01, 2008 6:07 AM
To: LazyDBA Discussion
Subject: RE: History File v8.2
Is a history file required in DB2? Absolutely! as its name suggests, for
recovery. Every backup, recovery, load, roll-forward, tablespace alter and
quiesce, reorg, stats and table drop is recorded and timestamped there.
That's from memory, there's probably a whole bunch of other stuff essential
for recovery that goes in there too.
You cannot sensibly 'move' a history file to a new directory as such - it
needs to be in its default location, because that's where DB2 will look for
it and there's no way to tell the engine to look for it elsewhere. The
command you refer to simply updates the reference to the location of a
backup within the RHF file itself.
What underlies your question? why do you want to move the RHF? If you are
concerned by its size, consider the PRUNE HISTORY command, and the per
partition REC_HIS_RETENTN and NUM_DB_BACKUPS db cfg parameters.
Regards
Alex Levy
Sustainable Software Ltd.
-----Original Message-----
From: Terry Gilbert
[mailto:db2udbdba-ezmlmshield-x78394382.[Email address protected]
Sent: 30 April 2008 21:41
To: LazyDBA Discussion
Subject: History File v8.2
Few history file questions,
Is a history file required in db2? (If not, can I turn it off or disable
it?)
If I have to have one, how do I move it? The update history location
command seems to apply to entries inside the history file somehow - doc is
unclear.
Thanks in advance
T
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