Re: database errors - Mailing list pgsql-hackers

> -----Original Message-----
> From: pgsql-hackers-owner@postgresql.org
>
> > > pg_dump: ERROR:  XLogFlush: request 0/A971020 is not satisfied ---
> > >   flushed only to 0/5000050 ... lost synchronization with
> server, resetting
> > > connection
> >
> > Okay, you have a page with an LSN of A971020 which is past end of XLOG
> > (5000050).  You may have created this problem for yourself by doing
> > pg_resetxlog with poorly chosen parameters.
>
> Michael,
>
> >From reading this error logs, it would appear that this system has been
> very strangely configured indeed.
>
> The recommendations for usage are fairly clear
> - don't use it on NFS....not cause we hate NFS....its just unsuited to
> the task of serving files to a database system
> - don't delete the transaction logs manually...they get recycled soon
> enough anyhow
>
> [ Is there a connection between the fact that it is on NFS and the logs
> have been manually deleted?

From what I know this was an attempt to make things better after they
ran into bad problems. There's no direct indication these problems
were in any way related to NFS, but I can't exclude this chance either.
They ran pg_resetxlog without any arguments, then ran it with -f.
(Perhaps this was done more than once) At some point they deleted the logs.
And the errors I posted above were generated after I got the copy of this
database and started experimenting with it.

> We know that SQLServer allows a "truncate transcation log" facility....
> is that something that you were expecting to see and trying to emulate
> with PostgreSQL? Were you trying to stop NFS writes taking place?
No, I don't think this was the idea.

> Your logs are rated very low. Is the transaction rate very low on this
> system or has the system recently been set up?
This was a very fresh database indeed.

> ... what is the benefit of using NFS?
> PostgreSQL offers client/server access - so why not use that instead?

We don't have a full control over this. The database is a relatively small
piece of a larger system, which includes the customized Apache server and
a number of other modules as well. Setting up the system involves some rules
and restrictions, one of them is that we don't yet support installing the
database server on a different host. (If this is what you meant)
We may actually support it soon, this is not a problem.
But NFS is an entirely another issue - our customers often install database
on NFS.
I am not sure if we can ever prevent it...
Thank you,
Mike

P.S. This is not the first time I'm bringing my problems to this list,
and I sincerely want to thank you, folks for responsiveness and help...

>
> Best Regards,
>
> Simon Riggs