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Re: Backup of live database

From: "Brian Modra" <epailty(at)googlemail(dot)com>
To: "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: Backup of live database
Date: 2008-01-16 08:24:00
Message-ID: 5a9699850801160024y7abdcd2fjdb1035c2070797eb@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-admin
Sorry to be hammering this point, but I want to be totally sure its OK,
rather than 5 months down the line attempt to recover, and it fails...

Are you absolutely certain that the tar backup of the file that changed, is
OK? (And that even if that file is huge, tar has managed to save the file as
it was before it was changed - otherwise I'm afraid that the first part of
the file is saved to tar, and then the file is modified, and the last part
of the file is saved to tar from the point it was modified - and so
therefore not consistent with the first part... And therefore the file has
lost its integrity, so even a WAL restore won't help because the base files
themselves are corrupt in the tar file?

On 16/01/2008, Joshua D. Drake <jd(at)commandprompt(dot)com> wrote:
>
> Brian Modra wrote:
> > The documentation about WAL says that you can start a live backup, as
> > long as you use WAL backup also.
> > I'm concerned about the integrity of the tar file. Can someone help me
> > with that?
>
> If you are using point in time recovery:
>
> http://www.postgresql.org/docs/8.2/static/continuous-archiving.html
>
> You do not have to worry about it.
>
> Joshua D. Drake
>
>
>
>
>
>
> >
> > On 16/01/2008, *Joshua D. Drake* <jd(at)commandprompt(dot)com
> > <mailto:jd(at)commandprompt(dot)com>> wrote:
> >
> >     Brian Modra wrote:
> >      > Hi,
> >      > If tar reports that a file was modified while it was being
> archived,
> >      > does that mean that the file was archived correctly, or is it
> >     corrupted
> >      > in the archive?
> >      > Does tar take a snapshot of the file so that even if it is
> >     modified, at
> >      > least the archive is safe?
> >
> >     You can not use tar to backup postgresql if it is running.
> >
> >     http://www.postgresql.org/docs/8.2/static/backup.html
> >     <http://www.postgresql.org/docs/8.2/static/backup.html>
> >
> >     Sincerely,
> >
> >     Joshua D. Drake
> >
> >      > Thanks
> >      >
> >      > --
> >      > Brian Modra   Land line: +27 23 5411 462
> >      > Mobile: +27 79 183 8059
> >      > 6 Jan Louw Str, Prince Albert, 6930
> >      > Postal: P.O. Box 2, Prince Albert 6930
> >      > South Africa
> >
> >
> >
> >
> > --
> > Brian Modra   Land line: +27 23 5411 462
> > Mobile: +27 79 183 8059
> > 6 Jan Louw Str, Prince Albert, 6930
> > Postal: P.O. Box 2, Prince Albert 6930
> > South Africa
>
>


-- 
Brian Modra   Land line: +27 23 5411 462
Mobile: +27 79 183 8059
6 Jan Louw Str, Prince Albert, 6930
Postal: P.O. Box 2, Prince Albert 6930
South Africa

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Subject: Re: trigger run of archive_command?
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Subject: Re: Backup of live database

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