Re: Recommended File System Configuration

james(at)jamesthornton(dot)com (James Thornton) writes:
> Back in 2001, there was a lengthy thread on the PG Hackers list about
> PG and journaling file systems
> (http://archives.postgresql.org/pgsql-hackers/2001-05/msg00017.php),
> but there was no decisive conclusion regarding what FS to use. At the
> time the fly in the XFS ointment was that deletes were slow, but this
> was improved with XFS 1.1.
>
> I think a journaling a FS is needed for PG data since large DBs could
> take hours to recover on a non-journaling FS, but what about WAL files?

If the WAL files are on a small filesystem, it presumably won't take
hours for that filesystem to recover at fsck time.

The results have not been totally conclusive...

- Several have found JFS to be a bit faster than anything else on
Linux, but some data loss problems have been experienced;

- ext2 has the significant demerit that with big filesystems, fsck
will "take forever" to run;

- ext3 appears to be the slowest option out there, and there are some
stories of filesystem corruption;

- ReiserFS was designed to be real fast with tiny files, which is not
the ideal "use case" for PostgreSQL; the designers there are
definitely the most aggressive at pushing out "bleeding edge" code,
which isn't likely the ideal;

- XFS is neither fastest nor slowest, but there has been a lack of
reports of "spontaneous data loss" under heavy load, which is a
good thing. It's not part of "official 2.4" kernels, requiring
backports, but once 2.6 gets more widely deployed, this shouldn't
be a demerit anymore...

I think that provides a reasonable overview of what has been seen...
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