Re: Power outage and funny chars in the logs

> From: Albe Laurenz <laurenz(dot)albe(at)wien(dot)gv(dot)at>
> Subject: RE: [GENERAL] Power outage and funny chars in the logs
> To: glynastill(at)yahoo(dot)co(dot)uk, pgsql-general(at)postgresql(dot)org
> Date: Thursday, 7 May, 2009, 2:44 PM
> Glyn Astill wrote:
> > We had a power outage today when a couple of computer
>
> > controlled power strips crashed (my secondary
> psu's will stay
> > firmly in the wall sockets now though).
> >
> > I'd had a lot of fun pulling plugs out under load
> before we
> > went into production so I wasn't particularly
> worried, and
> > the databases came back up and appled the redo logs as
> expected.
> >
> > What did make me scratch my head was a short stream of
> @
> > symbols (well they show up as @ symbols in vi) in the
> log
> > file of the main server (others are slony
> subscribers).
> >
> > My only reasoning so far is that it's just garbage
> from
> > postgres as the power died? The contorllers have BBU
> cache
> > and drive caches are off. The only other thing I can
> think is
> > it's something to do with me using data=writeback
> on the data
> > partition, and relying on the wal for journaling of
> the data.
> > The logs are on that same partition...
> >
> > Just wondered what you chaps thought about this?
>
> You mean the error log and not the transaction log, right?
>

Yes just the text based server logs.

> I would say that the file system suffered data loss in the
> system crash, and what you see is something that happened
> during file system recovery.
>
> The strange characters are towards the end of the file,
> right?

Yeah right at the end

> Can you find anything about file system recovery in the
> operating system log files?

As tom said in his post, I think this is just down to os cache of the server log etc - it's not actually flushed to disk with fsync like the wal.