Re: Simulating WAL on separate disks - Mailing list pgsql-general

From Tom Lane
Subject Re: Simulating WAL on separate disks
Date
Msg-id 9972.1105400802@sss.pgh.pa.us
Whole thread Raw
In response to Simulating WAL on separate disks  ("Guy Rouillier" <guyr@masergy.com>)
List pgsql-general
"Guy Rouillier" <guyr@masergy.com> writes:
> We are soon to be doing performance testing.  Our testing environment
> contains 4 SCSI disks in a RAID5 configuration, while our production
> environment will have 6 SCSI disks, which I'm suggesting we allocate as
> 4 in RAID5 for data and 2 in RAID1 for WAL.

> Because we don't have separate disks for WAL in our test environment,
> I'd like to minimize the effect of WAL.  I've read the sections in both
> the tuning guide and the base documentation, and I'm still a little
> unclear about fsync and wal_sync_method.  If I set fsync FALSE, does
> this disable WAL entirely?

No, but in any case it would entirely invalidate any performance testing
you might do.  fsync off is a completely different regime of operation
(unless perhaps you have hardly any updates).

            regards, tom lane

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