Re: Rman Explanation Please

From: Palooka <>
Date: Thu, 31 Jul 2008 00:02:29 +0100
Message-ID: <6q6kk.106606$Gb2.31295@newsfe29.ams2> wrote:
> Hi,
> We just implemented RMAN and were reading the documentation and came
> across this:
> "For example, you can implement a three-level backup scheme so that a
> full or level 0 backup is taken monthly, a cumulative level 1 is taken
> weekly, and a differential level 1 is taken daily. In this scheme, you
> never have to apply more than a day's worth of redo for complete
> recovery."
> We;re trying to understand that. The monthly level 0 is obviously a
> full database backup. We do not understand the difference between the
> cumulative level 1 and the differential level 1 if both seem to use
> the monthly 0 as a source.
> How does that all fit into only needing 1 days worth of logs??
> Thanks all, we all appreciate it.

In principle, if you have your level 0 backup available, plus all your incrementals, you can apply them all, and only need your logs since the last incremental backup. But if it's the wrong day you might need to restore 8 backups, plus apply today's redo.

Instictively I prefer cumulative incremental backups if it is feasible. That way, you only need to restore one full backup, one cumulative incremental, then apply archive logs since the last backup and the online redo.

Palooka Received on Wed Jul 30 2008 - 18:02:29 CDT

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