Re: Filesystem Direct I/O and WAL sync option - Mailing list pgsql-performance

On Tue, Jul 03, 2007 at 04:06:29PM +0100, Heikki Linnakangas wrote:
> Dimitri wrote:
> >I'm very curious to know if we may expect or guarantee any data
> >consistency with WAL sync=OFF but using file system mounted in Direct
> >I/O mode (means every write() system call called by PG really writes
> >to disk before return)...
>
> You'd have to turn that mode on on the data drives as well to get
> consistency, because fsync=off disables checkpoint fsyncs of the data
> files as well.

BTW, it might be worth trying the different wal_sync_methods. IIRC,
Jonah's seen some good results from open_datasync.
--
Jim Nasby                                      decibel@decibel.org
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)