I am just quoting my learned college in Mentor, who was advised by Rational that incremental backups were not the way to go. I see your point that there's little you can do with a volume of your size, but since we are talking about a database with file history, should you suffer any mishap in your backup software, would that cause a major problem in your ability to restore?
We use netbackup, and I know there are times when the software misses a backup. It did last night!
Simon -----Original Message----- From: John Stoffel To: Clawson, Simon Cc: 'Kumar, Rahul'; toasters@mathworks.com Sent: 27/06/03 22:03 Subject: RE: Clearcase and Netapp
Simon> This kind of adds weight to the argument for having a separate Simon> volume. You are not wise to do incremental backups of CC Simon> data. There is no real way to restore an incremental, so full Simon> backups are required, and this means nightly full backups of Simon> the whole CC data. If you are chucking other data in there as Simon> well this means full nightly backups of ALL your data! CC data Simon> grows fast, so will be a big lump on its own.
I just wanted to chime in here and say that this is wrong, incremental backups of VOBs data works just fine, as long as the previous full and all the incrementals were properly locked when the backup was made.
We use Legato Networker with incremental backups on our VOBs and we've never had a problem. Since the VOBs are around 300gb for a full backup, and 60gb a night for incrementals, it's a *huge* savings in tape to do it this way.
You need to make sure that your backup software offers a true incremental restore option though, plain old dump/restore won't work right since it doens't handle files that existed in the full, but not in the incremental case.
John John Stoffel - Senior Unix Systems Administrator - Lucent Technologies stoffel@lucent.com - http://www.lucent.com - 978-399-0479
Simon> I am just quoting my learned college in Mentor, who was advised Simon> by Rational that incremental backups were not the way to go.
I can understand their rational (sorry for the pun), since making full backups each time reduces the chances of any data loss, but the time to do so each night is prohibitive. Though these days, using either VxFS filesystem snapshots, or storing the VOBs on toasters and using snapshots there, you can do the backups outside of normal hours, or even export the data to another host and dothe backups there. It depends on your money mostly. :]
Simon> I see your point that there's little you can do with a volume Simon> of your size, but since we are talking about a database with Simon> file history, should you suffer any mishap in your backup Simon> software, would that cause a major problem in your ability to Simon> restore?
Sure, but since Legato (and NetBackup as I understand it, still not intimately familiar with it) dumps the file indexes with each backup, in the worst case I can just scan the backups to do a restore.
And when you're doing a restore of a VOB, you're restoring *all* the data, just not specific files, since you need to restore them all to the same known state to guarenttee that you get a good VOB db back.
Simon> We use netbackup, and I know there are times when the software Simon> misses a backup. It did last night!
Now if you were using a toaster for backup storage, you'd be backing up the snapshot, and of course you'd keep a couple of days of snapshots around for just such an occurance?
The nice thing about VOB backups, is that after a while you're not going to go back and restore them, since the data is cummulative (ideally, I'm ignoring if you purposefully nuke data in your VOBs). So once a week or two have gone by, you really don't need the backups, since the data is there.
John John Stoffel - Senior Unix Systems Administrator - Lucent Technologies stoffel@lucent.com - http://www.lucent.com - 978-399-0479
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Clawson, Simon -
John Stoffel