Re: tape backups

Thanks for the pointer. This does look like what I want, because in
retrospect I don't know how I would know which wal logs I would start
to replay after a given pg_dumpall to bring myself up to the present
after a recovery.

But, this page confuses me when it talks about pg_start_backup and
pg_stop_backup. What do these functions do? It seems like they do
nothing more than let me know which wal files were in use over the
duration of the backup, which is certainly useful. But they do NOT
seem to freeze the actual data files, and it seems to me that because
the data files won't be archived atomically while they may be
changing, that I might end up with corrupted data files that a replay
of wal files wouldn't correct. Is my fear groundless?

On Dec 23, 2006, at 10:20 AM, Shoaib Mir wrote:

> I think you might want to do incremental backups so a better
> approach to that as you mentioned too will be WAL files. For
> details you can refer to --> http://www.postgresql.org/docs/current/
> static/continuous-archiving.html
>
> --------------------
> Shoaib Mir
> EnterpriseDB (www.enterprisedb.com)
>
> On 12/23/06, Ben <bench(at)silentmedia(dot)com> wrote:
> Hi everybody,
>
> I'm trying to find a good solution to making backups to tape, where I
> want to define "good" as:
>
> - easy to use, like pg_dumpall, BUT
> - not in a single file, so I don't backup my entire database cluster
> with every differential backup
>
> As I understand my backup program (Bacula) if a file changes at all
> between differential backups then it gets backed up again in its
> entirety. That seems pretty reasonable. So now I'm trying to figure
> out how to get my postgres dump to end up in files in such a way that
> little change in data means few file changes. But if there's no
> native tool to do that (and it seems like there isn't) then setting
> up something like that sounds like it might be a pain, as would
> restoring from it.
>
> Am I going about this the wrong way? Would it just be easier to do a
> full pg_dumpall for my full backups and then build up a list of WAL
> files with each differential? How do other people do it?
>
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