Lists: | pgsql-admin |
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From: | "Ed Murphy" <emurphy1(at)email(dot)arizona(dot)edu> |
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To: | <pgsql-admin(at)postgresql(dot)org> |
Subject: | Snapshot as Backup |
Date: | 2004-01-13 17:15:34 |
Message-ID: | 000901c3d9f8$db4a1cd0$33a48796@ilc.arizona.edu |
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Lists: | pgsql-admin |
Hello,
I'm using Red Hat Enterprise v2.1 and PostgreSQL v7.3.4. Our hardware
setup includes a large Storage Area Network (SAN). The systems folks
are going to utilize a snapshot type backup to backup the file system.
This snapshot will include PGDATA and all the PostgreSQL files. My
question is if I restore this snapshot will PostgreSQL work? I know if
doing a typical file system backup of PostgreSQL I must first stop the
postmaster or the backup will not produce a useable PostgreSQL system.
Is it necessary to stop the postmaster for this snapshot backup also?
Thanks,
Ed Murphy
The University of Arizona
From: | "Matt Clark" <matt(at)ymogen(dot)net> |
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To: | <emurphy1(at)email(dot)arizona(dot)edu>, <pgsql-admin(at)postgresql(dot)org> |
Subject: | Re: Snapshot as Backup |
Date: | 2004-01-13 17:59:09 |
Message-ID: | OAEAKHEHCMLBLIDGAFELKEBNEHAA.matt@ymogen.net |
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Lists: | pgsql-admin |
MessageThe consensus from previous discussions (search for 'LVM' in the
archives) is essentially that it definitely *should* work, some people *do*
use it successfully, but that you *must* test it thoroughly in your own
setup under heavy write load before relying on it.
PG will believe it has 'crashed' when you start it from a restored snapshot,
and PG is designed to recover perfectly well from crashes. If you stop the
postmaster before the snapshot is taken then it will definitely work fine.
Matt
-----Original Message-----
From: pgsql-admin-owner(at)postgresql(dot)org
[mailto:pgsql-admin-owner(at)postgresql(dot)org]On Behalf Of Ed Murphy
Sent: 13 January 2004 17:16
To: pgsql-admin(at)postgresql(dot)org
Subject: [ADMIN] Snapshot as Backup
Hello,
I'm using Red Hat Enterprise v2.1 and PostgreSQL v7.3.4. Our hardware
setup includes a large Storage Area Network (SAN). The systems folks are
going to utilize a snapshot type backup to backup the file system. This
snapshot will include PGDATA and all the PostgreSQL files. My question is
if I restore this snapshot will PostgreSQL work? I know if doing a typical
file system backup of PostgreSQL I must first stop the postmaster or the
backup will not produce a useable PostgreSQL system. Is it necessary to
stop the postmaster for this snapshot backup also?
Thanks,
Ed Murphy
The University of Arizona
From: | Sai Hertz And Control Systems <sank89(at)sancharnet(dot)in> |
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To: | emurphy1(at)email(dot)arizona(dot)edu |
Cc: | pgsql-admin(at)postgresql(dot)org |
Subject: | Re: Snapshot as Backup |
Date: | 2004-01-13 20:30:45 |
Message-ID: | 40045575.60007@sancharnet.in |
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Lists: | pgsql-admin |
Dear Ed Murphy ,
> and all the PostgreSQL files. My question is if I restore this
> snapshot will PostgreSQL work? I know if doing a typical file system
> backup of PostgreSQL I must first stop the postmaster or the backup
> will not produce a useable PostgreSQL system. Is it necessary to stop
> the postmaster for this snapshot backup also?
>
Yes if the snapshot (filesystem) backup and restore is performed when
postmaster is NOT running you can reproduce it.
I have done this with command
dump <-- for file system backup
Filesystem ext3
Regards
Vishal Kashyap
From: | Jeff <threshar(at)torgo(dot)978(dot)org> |
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To: | aspire420(at)hotpop(dot)com |
Cc: | sank89(at)sancharnet(dot)in, emurphy1(at)email(dot)arizona(dot)edu, pgsql-admin(at)postgresql(dot)org |
Subject: | Re: Snapshot as Backup |
Date: | 2004-01-16 14:54:29 |
Message-ID: | 20040116095429.0bbc6b86.threshar@torgo.978.org |
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Lists: | pgsql-admin |
On Wed, 14 Jan 2004 02:00:45 +0530
Sai Hertz And Control Systems <sank89(at)sancharnet(dot)in> wrote:
>
> > and all the PostgreSQL files. My question is if I restore this
> > snapshot will PostgreSQL work? I know if doing a typical file
> > system backup of PostgreSQL I must first stop the postmaster or the
> > backup will not produce a useable PostgreSQL system. Is it
> > necessary to stop the postmaster for this snapshot backup also?
> >
I've done testing on this. It works fine.
Just make sure you're doing a filesystem snapshot and not a "cp".
To PG it just looks like the power went out or some other failure.
It'll replay parts of its log and be on its merry way. This is *much*
faster than using pg_dump / pg_restore, especially on huge db's.
If you are using xfs you may want to wrap the snapshot call with
xfs_freeze/unfreeze.
It may also be nice every once in a while to do a normal pg_dump..
--
Jeff Trout <jeff(at)jefftrout(dot)com>
http://www.jefftrout.com/
http://www.stuarthamm.net/