Thanks Dan, good suggestion, subject duly changed...
Our DBAs are well aware of the implications of disaster recovery, we have
another site with DR hardware, which in the long term will have a hot-standby
database with logs shipped up to it and suchlike. For various reasons (don't
ask; not the DBAs' fault, though) that's not ready yet. In the meantime, we've
got agreement from the business that an outage of "probably a few days" is
acceptable for the application as it now stands (it's a work in progress) in
the event of a disaster.
The backup process we've got in place was always acknowledged to be a (cheap)
interim solution to cover us until we got a "proper" backup solution - meaning
one which would scale up to handle a 7TB database backup daily. As it stands,
as we've implemented it, Bacula doesn't; what I'm doing is trying to work out
whether Bacula can be the "final" solution, or whether we need to move to
something like Networker + RMAN. Or Bacula + RMAN, if I can find a good
description of how to integrate them together. Or some other solution if
someone can suggest one!
DJ
-----Original Message-----
From: Dan Langille [mailto:dan AT langille DOT org]
Sent: Wednesday, 26 November 2008 09:20
To: David Jurke
Cc: bacula-users AT lists.sourceforge DOT net
Subject: Re: [Bacula-users] How to set up large database backup
On Nov 25, 2008, at 2:03 PM, David Jurke wrote:
> Hiya Dan,
>
> I'm not a DBA, so I don't know the internal details, but to do a hot
> backup with Oracle you have to put it into hot backup mode, take a
> copy of the data files, take it out of backup mode, switch logs, and
> back up all the log files. Then at restore time you restore all the
> data files and fire up Oracle. It will ask for all the log files and
> apply them, thus bringing the database back into a consistent state.
>
> The problem is, while the hot backup is running it's got to write a
> copy of all the transactions to log files, to leave the data files
> in a semi-consistent state while you back them up. We're an
> international telco, the database is receiving call detail records
> for every phone call in or out of our network; I'm told the volume
> of records is about five times the total of all the banking
> transactions handled by all the banks in the country (NZ) combined.
> Over the several hours it takes to back up the database, this
> creates a lot of extra log files, hence the one-tablespace-at-a-time
> scheme to keep it down a bit.
>
> The DBAs have provided a script to do this, taking a copy of the
> data files to disk, over NFS. This is a proven method, and works
> well... for now. But the database is fairly new and hence small
> (700GB) and is expected to grow by roughly an order of magnitude, so
> we will a) run out of disk space to copy it to, and b) run out of
> time in the day to back it up. Part of the latter problem is that
> we're copying the data twice - once to disk, and then again from
> disk to tape - so the backup is taking twice as long as it could be.
>
> I really need to find a way to back it up straight to tape,
> integrated with (though not necessarily using) Bacula backing up the
> other servers in our environment. Hence my mention of scripting
> around bits of Bacula functionality, integrating Bacula into the
> DBAs' script.
>
> Or, if it's not possible, someone please tell me there's no way to
> do it and we'll go and spend some money on something like Legato
> Networker + Oracle RMAN. I like Bacula, it has a few quirks but
> seems good at what it does, but I suspect maybe Kern hasn't got a
> multi-terabyte SAN-based Oracle environment sitting around for him
> to play with, so handling some of the "larger" problems may be out
> of scope... *grin*
I think it would be much better if you started a new thread with a
more descriptive topic (e.g. best practices for large Oracle
backups). You want the Oracle people in on this thread. At the
moment, you're probably not getting their attention. Also, Google for
Oracle backups.
I also think your DBA team needs to look at disaster recovery options:
- the DBA server hardware has died
- the disks are dead
- etc
If the time it would take to restore from a backup is insufficient,
then they really need to look at replicas.
--
Dan Langille
http://langille.org/
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