On Fri, 2010-03-12 at 18:19 +1300, Jim Cheetham wrote: > On Fri, Mar 12, 2010 at 1:34 PM, Steve Holdoway <[email protected]> > wrote: > > I wouldn't do that with the backups personally. If you're after backing > > up important production databases, then I'd look at replicating them > > ( to another machine preferably ) as a frist line of defence. > > Replication gives you defence from hardware failure, the same way that > RAID does. But it has nothing whatsoever to do with being a "backup" > in the data sense. Except ... > > > whilst over there, cold backups have no effect on live systems > > performance... > > The only effect that they have is to push back on your replication > system :-) As long as the primary doesn't get excess load while > waiting for the replicant to come back up, you're in business. Well, it just extends the list of changes to be made. No different to adding rows to a table. > > > and no matter how cumbersome they are, I reckon they > > should always be a part of your backup strategy (: > > Sure, but effectively that's what a snapshot is; if a full cold backup > takes say 1 hour, with LVM snapshotting you can reduce that to a > couple of seconds. Surely that's worth investigating? If you can grab > a snapshot that quickly (it'll still take an hour to actually back up > from there, but the DB doesn't have to know), and your production > system can handle being read-only for a second or so, you can dispense > with the need for a replicant in the first place. I disagree. LVM doesn't magically invent performance, which it must do to provide the 'virtual' instant backup you're talking about. The server still suffers. If this isn't a problem, then this is not really relevant.
The big difference between this setup and what I'm recommending is that you've moved the whole of your non production oriented services away from the production server, which means that it can do what it needs to - support the live services. The replicated database can then be secured with minimal effect on this database or server. > > -jim
