[SOLVED] Are Incremental Backups Worth It?

[the_griz]

I can run a full backup of my NE zimbra installation to a drive with no other full backups and it takes seven hours. All incremental backups after that take mere seconds to do. Zimbra tech explained to me that was because the incrementals basically copy the redo logs.

However, the redo logs don't include incoming/outgoing email between the time of the full backups and the time of the incremental, correct? I thought the redo logs only do message movements (between folders) and deletions, etc.

If this is the case, how would one ever do a full point in time recovery of person's email if there are incrementals involved.

In two years, I have had to only do one person's full recovery of their email account. I had a full backup plus 4 incrementals. Only the full backup had mail messages. After the full backup the person lost their subsequent incoming/outgoing.

Am I just completely wrong on the definition of an incremental backup? Aren't they supposed to have all incoming and outgoing messages/attachments that came in AFTER the last full backup?

If you could shed some light on this, it would be appreciated. Otherwise, I think I am goiing to bag the incremental backups for nightly full backups.

Thansk!

[bdial]

redologs have everything. messages sent, received, moved, deleted, marked. you can basically replay a redolog over a backup and get an account to reflect how it existed at any time down to the second

[the_griz]

Originally Posted by bdial

redologs have everything. messages sent, received, moved, deleted, marked. you can basically replay a redolog over a backup and get an account to reflect how it existed at any time down to the second

Thanks for the information. I guess since I had that one bad experience with recovering that one user's mail store, I felt there was something else I was doing wrong.

I will have to try with an active account just to convince myself it really works properly.

Thanks!

[dave_kempe]

Had a customer call up the other day, wanting us to restore his email back to how it was fifteen minutes ago. He just realised he deleted a bunch of mail or something.
I was able to do this:
zmrestore -s server.domain -a user@domain -restoreToTime "2010/08/03 11:15:00" -ca -pre restored_

and it worked a charm.

[LMStone]

There's another reason to do incremental backups periodically:

If you don't, the redo logs just keep keep building up. Only an incremental backup moves the redo logs into the ~/backup folder, where they will be purged according to your backup days retention policy.

Put differently, no incremental backups means you will fill up your hard disk eventually with old redo logs from the dawn of time!

Hope that helps,
Mark

[ewilen]

If you really don't want to do incrementals, then this post contains the secret to keeping the redologs from piling up: Of backups and restoration

But I agree that incrementals are worthwhile.

But seven hours for a full backup? Are you using zipped or nonzipped full backups? How many users do you have? (And what's the average mailbox size?)