Ah, yes, you're right, I'm with you now. You're kicking off a whole lot of 
parallel opens which all block, then get unblocked one at a time as Bacula 
starts reading them, at which point the tablespace is altered and the file 
copied to the FIFO and hence to tape. I hadn't clicked that the tablespace 
alter would only happen *after* Bacula started trying to read the file.

So as long as there's no timeout on Bacula trying to read the FIFO before the 
database is altered and the copy starts writing to it (which should be quick) 
and also on the open of the FIFO before Bacula starts reading to it (which 
would be hours), all is happy.

I'll have a bit of a play with this, see if I can make it work and, most 
importantly, make sure I can restore a working database from it! (Beware of 
filenames!) This may take some time...


Cheers,

David.

-----Original Message-----
From: Kjetil Torgrim Homme [mailto:kjetilho AT linpro DOT no] 
Sent: Thursday, 27 November 2008 16:56
To: bacula-users AT lists.sourceforge DOT net
Subject: Re: [Bacula-users] How to set up large database backup

"David Jurke" <David.Jurke AT tnzi DOT com> writes:

> I think it'd need some tweaking to delay putting each tablespace
> into backup mode until Bacula is ready to back it up - one of the
> problems I have is that we can't put all the tablespaces into backup
> mode at the same time because of the volume of logs produced.

the open of the FIFO will not return until Bacula is there wanting to
read the data, so do the locking after the "Dumping $ts" line.

> Perhaps I could run a script before the backups start to query the
> database for a list of tablespaces, and build a set of Bacula job
> configs, one per tablespace, then tell Bacula to reload its config.

you could do that, but I don't think you gain anything.  the code I
included is intended to be a pre-script, where the @tablesspaces
initilisation at the top should be replaced by a database query.

> In fact, Would I need to dump the database to anything? Wouldn't I
> just have a pre-backup job to put the tablespace into backup mode,
> bacula that tablespace's file straight to tape, then a post-backup
> to put the tablespace back to normal?

indeed.  with my script, you don't actually have a post-backup script,
though -- the tablespace twiddling is done in the FIFO handling
process which exits as soon as Bacula is done reading.

-- 
regards,          | Redpill  _
Kjetil T. Homme   | Linpro  (_)


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