Re: Power outage and funny chars in the logs

From: Glyn Astill <glynastill(at)yahoo(dot)co(dot)uk>
To: "Massa, Harald Armin" <chef(at)ghum(dot)de>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Power outage and funny chars in the logs
Date: 2009-05-07 15:06:54
Message-ID: 851078.50908.qm@web23606.mail.ird.yahoo.com
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--- On Thu, 7/5/09, Massa, Harald Armin <chef(at)ghum(dot)de> wrote:

> >
> > mentioning those @@@@@ symbols ...
>
> 1,5 weeks ago there was reported on this list the problem
> "postgres service
> not starting on windows"; after consulting event log
> the user reported as
> message "bogus data in postmaster.pid". After
> deleting postmaster.pid the
> service started up fine.
>
> Soon after a customer of mine reported the same error, also
> on windows; and
> before deleting postmaster.pid I got a copy of that
> "bogus one". AND: there
> where also a lot of @@@@ symobols in postmaster.pid (hex 0)
>
> After reading the answers to the funny chars in the logs
> and no fsync on the
> logs: is there a fsync on postmaster.pid? Or is that file
> not considered
> important enough?
>
> (just digging for the reason for corrupted data in
> postmaster.pid)...
>

Aha, nice one Harald,

So the @ symbols are hex 0. Perhaps all the @ symbols are the pattern of the text that was written to the log - but since ext3 is in data=writeback mode it knows that there should be some data there *but* it doesn't know what that data is, so it just ends up as 0's.

With regards to your question, if the .pid is not fsynced I agree doing so would perhaps be a good idea, is there any reason why not to?

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