Re: restore challenge - Mailing list pgsql-admin

From Christopher Browne
Subject Re: restore challenge
Date
Msg-id m38xvm3bmj.fsf@mobile.int.cbbrowne.com
Whole thread Raw
In response to restore challenge  ("Yogvinder Singh" <yogvinder@newgen.co.in>)
List pgsql-admin
> On Thu, Nov 17, 2005 at 02:04:42PM -0500, Chris Browne wrote:
>> If your OS or disk hardware supports some sort of "snapshotting"
>> technology, so that you can grab a copy of the whole thing as an
>> instant atomic operation, that provides a way to grab a copy while
>> postmaster is running.  If not, then you have to take a copy while the
>> postmaster is shut down.
>
> It's also worth noting that you _really really_ want to test that
> snapshotting capability.  I've heard some people grumble about "it
> didn't work for me" or some such.  There are others who've reported
> it works (and it ought to, if the snapshots work as advertised --
> just be sure you know what the snapshots actually are).

To add a grumble, of sorts...

People get all excited about separating WAL onto separate disk, to
improve performance.

Unfortunately, if you do that, that separates the database into two
portions, "splitting the atom," as it were.  You'll no longer be able
to get that atomic snapshot.  Oops.
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