Re: Write errors in postgres log

Hello Tom,

Thanks for the response. My replies inline...

On 2/18/07, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> "CAJ CAJ" <pguser(at)gmail(dot)com> writes:
> > We have 2 servers running postgres database 8.0.3 serving a web
> application.
>
> You do realize we are up to 8.0.12 in that branch? You're missing
> nearly two years worth of bug fixes.

Yes we're aware of it. The web-application is from a 3rd party vendor and
comes bundled with postgresql 8.0.3. Is there a specific fix in the recent
releases that might have fixed the data corruption I described? We can then
request the vendor to upgrade their software stack including Pg. I'm also
concerned about the security fixes as well.

> ERROR: xlog flush request 2/66B19020 is not satisfied --- flushed only to
> > 2/5F8F95A2 ...
> > CONTEXT: writing block 754 of relation 1663/17230/17443
>
> Looks a bit ugly --- might be worth looking at that block with
> pg_filedump to see what the extent of the corruption is.

Will try pg_filedump and let you know what happens.

> 1. pg_reset_xlog did not work.
>
> Define "did not work". What did you do exactly, and what results did
> you get?

I apologize for the lack of information. I will get that to you as soon as I
can. In brief, ran pg_resetxlog which identified the last good WAL address.
Postgres successfully recovered at start but.pg_dump ran into similar
errors.

> 2. Recent backups are corrupted as well.
>
> It's not possible for a pg_dump backup to be affected by this problem.
> How exactly are you making your backups, and what happens when you try
> to use them?

We shutdown the database and make a copy of the pgdata directory.
pg_dump/pg_restore takes a long time to be used for backups. We are
exploring the PITR method (a little too late),

Since the data corruption goes way back, our recent backup is corrupted as
well (we see the same errors when we restore the old pgdata backup)

I appreciate your response and feel free to ask for any information that
might help.

Thanks