Re: Rman Explanation Please

On Jul 31, 8:42 am, artme..._at_yahoo.com wrote:
> On Jul 30, 6:02 pm, Palooka <nob..._at_nowhere.com> wrote:
>
>
>
>
>
> > artme..._at_yahoo.com 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
>
> Palooka,
>
> So, you may suggest a weekly level 0 incremental backup, backs up the
> entire database.  Then after that, cumulative level 0 backups for the
> rest of the week.  Should a restore be needed, then restore the level
> 0 incremental, then the level 0 cumulative, then archive
> logs......correct?
>
> Seems simple enough....
>
> Thank you.

Um, doesn't the level 0 incremental have all blocks?

You probably meant to say cumulative level 1 daily.

The incremental stuff is a trade-off for places that have too many changes to keep an incremental every day.

Not that I've ever tried it, just reading the docs. I've enough horsepower and disk to do a full every day. Getting it offnode is another issue, so I might start. But that depends on management, which is a more difficult problem.

jg

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