Re: [HACKERS] Re: PD_ALL_VISIBLE flag was incorrectly set happend during repeatable vacuum

On Wed, Mar 02, 2011 at 06:45:13PM -0300, Alvaro Herrera wrote:
> Excerpts from daveg's message of mié mar 02 18:30:34 -0300 2011:
>
> > After a restart and vacuum of all dbs with no other activity things were
> > quiet for a couple hours and then we started seeing these PD_ALL_VISIBLE
> > messages again.
> >
> > Going back through the logs we have been getting these since at least before
> > mid January. Oddly, this only happens on four systems which are all new Dell
> > 32 core Nehalem 512GB machines using iscsi partitions served off a Netapp.
> > Our older 8 core 64GB hosts have never logged any of these errors. I'm not
> > saying it is related to the hw, as these hosts are doing a lot more work than
> > the old hosts so it may be a concurrency problem that just never came up at
> > lower levels before.
> >
> > Postgresql version is 8.4.4.
>
> I don't see how this could be related, but since you're running on NFS,
> maybe it is, somehow:
> http://archives.postgresql.org/message-id/4D40DDB7.1010000@credativ.com
> (for example what if the visibility map fork's last page is overwritten?)

Running on ISCSI, not nfs. But it is still a Netapp, so who knows. I'll look.
Also, we are not seeing any of the "unexpected data beyond EOF" errors,
just thousands per day of the PD_ALL_VISIBLE error.

-dg

--
David Gould daveg(at)sonic(dot)net 510 536 1443 510 282 0869
If simplicity worked, the world would be overrun with insects.