On 12/12/07, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> Regular database files need metadata journalling (data=writeback mount
> option for ext3). This is quite faster than full-blown journalling
> which is what you get with default ext3 mount options. WAL files
> (pg_xlog) do not need any kind of journalling, so you can save the
> overhead and put them on an ext2 filesystem (or any other nonjournalled
> filesystem).
I think in practice there won't be a performance difference between
ext3 with 'data=writeback' and ext2 for WAL-the files are
preallocated, so the only activity that's occurring with any frequency
is fsync'd data writes to existing file blocks, which don't go through
the journal. So you might as well go with ext3 since (a) you won't
have to fsck, and (b) ext3 is the bog-standard Linux filesystem now
and as such gets the most testing--ext2 is gradually dropping into
obsolescence.
-Doug