Re: Backup/Recovery (BR) question

Hi,
Hi,

We do a back-up of our postgresql server by stopping it, takning a LVM
snapshot starting te server again (< 10 seconds), than we write the snapshot
to a tape.
Works fine, and with your theory it should be able to take the snapshot
without stopping postgresql. (to make the log replay work you at least need
the log & db files from the exact same moment in time).

See attached batch file (used with Redhat 9, LVM 1.0.7 and taper)

Regards,

Jean Huveneers

Xillion ICT Solutions B.V.
Marktplein 8
6243 BR  Geulle
The Netherlands

tel: +31 (0)43 3659244
fax: +31 (0)43 3659249
gsm: +31 (0)6 456 44 357
www: www.xillion.nl

> -----Original Message-----
> From: Robert Treat [mailto:xzilla@users.sourceforge.net]
> Sent: vrijdag 21 november 2003 7:55
> To: Oli Sennhauser
> Cc: pgsql-admin@postgresql.org
> Subject: Re: [ADMIN] Backup/Recovery (BR) question
>
>
> On Thursday 20 November 2003 18:00, Oli Sennhauser wrote:
> > Hello Robert
> >
> > >If you do  // drop database "DB1" // the first database will drop,
> > >though you might want to verify if it is really damaged.
> >
> > Oh sh....! It worked. Thanks. I am used to do the other way
> around (from
> > oracle).
> >
> > Do you have any idea to my second question?
> >
> > Q2: New situation: Why is it not a good idea to backup the database
> > files of a cluster incl. all c_log and x_log (log files
> last) to get a
> > "physicaly hot backup".
> > In principle it is the same situation like a server which
> is crashing
> > (not a once but during some time). After restoring, it
> should do a redo
> > and rollback automatically like after a crash. This methode
> (physical
> > hot backup) would increas backup and restore times dramatically.
> >
>
> Essentially I think you're right, it should behave much like
> a crashing
> server.  The main reason why people don't recommend it is
> that (depending on
> your os setup) there is the potential to lose data that has
> been commited but
> not actually written to disk.  Note that you shouldn't get
> corrupted data
> from this, but in many cases losing data is just as bad so we
> don't recomend
> it.  If you really want to do this, you should really either
> shut down the
> database  or get LVM going.
>
>
> Robert Treat
> --
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