Re: Backup & Restore

Ravip via DBMonster.com wrote:
> Hi Brian
>
> My backup strategy:
>
> Initial Level 0 backup
>
> daily level 2 backup
>
> weekly level 1 backup
>
> I have the clarifications below:
>
> 1. Should I take the archive log backups as part of daily and weekly backup ?
> My intention is to take the archive log backup separately. Is this
> recommended ?

How much data can you afford to lose? Note that this is a business decision since data is a corporate asset. That data has a value to the company. And when you get closer and closer to losing less and less data (or even zero data loss), the solution gets more expensive.

The reason I ask the above is that if you lose your database server, you can go to your backup tape (hopefully you have a backup on tape) and recover from your incremental backups. So that get's you to the point in time up to the backup. Your archived redo logs will get you the rest of the way. If you can only lose one hour's worth transactions, then you should back up your archived redo logs to tape once an hour. If you can lose a day's worth of transactions, then you should back up the archived redo logs at least once a day. If you can only lose 5 mins of transactions...or have a zero data loss requirement, then you should probably be looking at Data Guard.

How often you backup your archived redo logs depends on your data loss requirements. It does not matter if this is done seperately from your incremental backups or not. A RMAN backup of your archived redo logs is a RMAN backup no matter what else was backed up with it.

> 2. During the rotation I feel I can remove the level 2 backup taken on 1st
> week during the 5th week.
>
> The incremental backup merge in 10g can be used in my weekly backup. So that
> every week backup will be merged with Level 0 backup.
>
> I'm in a little confusion of using incremental backup with merging. My DB
> size is close 200GB and daily 7-8 archive log of each 500MB get generated.
> What kind of backup strategy will you recommend.?

To be honest, I cannot recommend a backup strategy because I do no know enough of your requirements. I already discussed data loss above. Your data loss requirement drives part of your backup strategy. And the one thing that many people do not look at hard enough when it comes to designing the backup strategy is the *recovery requirements*. What are your recovery requirements? Are you required to be up an running in one hour? 2 mins? 1 day? Are you required to be up and running at a remote site? There are other questions that could be asked as well. You mentioned the db size, and that is one requirement...you have to be able to back up a 200GB database with approximately 4GB of daily archived redo logs. But what about your recovery requirements? Those should be heavily weighed and factored in to your backup strategy. For instance, if you are required to restore all transactions within one hour of failure and you only perform cold backups and have no archived redo logs, then the backup strategy does not meet the recovery requirements.

HTH,
Brian

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Brian Peasland
dba_at_nospam.peasland.net
http://www.peasland.net

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