Re: Postgresql Performance on an HP DL385 and

On Tue, Aug 15, 2006 at 04:05:17PM -0400, Tom Lane wrote:
> mark(at)mark(dot)mielke(dot)cc writes:
> > 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?).
> At least for xlog, this worrying is misguided, because we zero and fsync
> a WAL file before we ever put any valuable data into it. Unless the
> filesystem is lying through its teeth about having done an fsync, there
> should be no metadata changes happening for an active WAL file (other
> than mtime of course).

Hmmm... I may have missed a post about this in the archive.

WAL file is never appended - only re-written?

If so, then I'm wrong, and ext2 is fine. The requirement is that no
file system structures change as a result of any writes that
PostgreSQL does. If no file system structures change, then I take
everything back as uninformed.

Please confirm whichever. :-)

Cheers,
mark

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