Re: Postgresql Performance on an HP DL385 and

On Tue, Aug 15, 2006 at 11:29:26AM -0500, Jim C. Nasby wrote:
> On Mon, Aug 14, 2006 at 01:09:04PM -0400, Michael Stone wrote:
> > On Mon, Aug 14, 2006 at 12:05:46PM -0500, Jim C. Nasby wrote:
> > >Wow, interesting. IIRC, XFS is lower performing than ext3,
> > For xlog, maybe. For data, no. Both are definately slower than ext2 for
> > xlog, which is another reason to have xlog on a small filesystem which
> > doesn't need metadata journalling.
> Are 'we' sure that such a setup can't lose any data? I'm worried about
> files getting lost when they get written out before the metadata does.

I've been worrying about this myself, and my current conclusion is that
ext2 is bad because: a) fsck, and b) data can be lost or corrupted, which
could lead to the need to trash the xlog.

Even ext3 in writeback mode allows for the indirect blocks to be updated
without the data underneath, allowing for blocks to point to random data,
or worse, previous apparently sane data (especially if the data is from
a drive only used for xlog - the chance is high that a block might look
partially valid?).

So, I'm sticking with ext3 in ordered mode.

Cheers,
mark

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