Re: What happens when wal fails?

Joseph Shraibman wrote:
> If I put the pg_xlog directory on its own disk, then that disk fails,
> does that mean the postgres is hosed or does it just mean that postgres
> no longer safe from a power outage? Does pg detect a problem with the
> wal and then call fsync() on the database files if wal isn't working?

I'm guessing hosed, or at least potentially so. You'd fit a new disk,
restart PG and it would complain that it couldn't re-run the WAL files.
That implies that at least some of your transactions might be lost.

Of course PITR would reduce the danger of this, even if you just copied
the WAL to another disk on the same machine.

I don't know about fsync-ing database files in their absence I'm afraid.

--
Richard Huxton
Archonet Ltd