Re: found xmin from before relfrozenxid on pg_catalog.pg_authid - Mailing list pgsql-general

From Peter Geoghegan
Subject Re: found xmin from before relfrozenxid on pg_catalog.pg_authid
Date
Msg-id CAH2-WznQE_R8v5RH7ZHF-J70cwV6AHZiQRwXdXqXNgc=qj3+ng@mail.gmail.com
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In response to Re: found xmin from before relfrozenxid on pg_catalog.pg_authid  (Jeremy Finzel <finzelj@gmail.com>)
Responses Re: found xmin from before relfrozenxid on pg_catalog.pg_authid  (Maxim Boguk <maxim.boguk@gmail.com>)
List pgsql-general
On Thu, Mar 22, 2018 at 2:24 PM, Jeremy Finzel <finzelj@gmail.com> wrote:
> I am running this on a san snapshot of our production system.  I assume that
> this will give me a valid check for file-system-level corruption.  I am
> going to kick it off and see if I find anything interesting.

It might. Note that SAN snapshots might have corruption hazards,
though. Postgres expects crash consistency across all filesystems, so
you might run into trouble if you had a separate filesystem for WAL,
for example. I know that LVM snapshots only provide a consistent view
of a single logical volume, even though many LVM + Postgres setups
will involve multiple logical volumes. This makes it possible for a
small inconsistency across logical volumes to corrupt data.

I don't know anything about your SAN snapshotting, but this is at
least something to consider.

-- 
Peter Geoghegan


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