Re: Backup Strategy

From: George Schlossnagle <george_at_omniti.com>
Date: Wed, 03 Oct 2001 15:35:18 -0700
Message-ID: <F001.003A13F4.20011003155016@fatcity.com>

The downtime tolerance really dictates the backup strategy. The tighter you rtolerances for recovery time, the more expensive the backup startegy you need to meet to guarantee it is. The way I approach these problems when laying out a backup strategy is:

figure out the cost and time to recovery, as well as the worst-case data loss for the situation i.e. if I have a 500G database and it takes 20 hours to restore from a full export, then a I can say that running exports nightly costs X dollars in labor and tapes, takes 20 hours to recover and I can loose up to a day of data. If I run nightly hot backups and store all archive redo log, then it costs X dollars in labor and hardware, has Y hours of mean time to recovery and incurs Z hours of worst-case data loss (loss of the online redo). Running a cluster environment with fully redundant hardware and a standby server costs M and provides N.
Take the downtime requiremnts as given to you by your management and then attach to them the appropriate cost as discovered in 1. If that is acceptable, great. If not, then you present the results you learned in one, detailing the costs and benefis of each method, until a cost/benefit combo acceptable to your management is reached.

I think the point of the responses you've recieved is that any degree of recoverability is possible, if you're willing to incur the cost. The key is to figure out what cost is acceptable.

George

Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Wednesday, October 03, 2001 5:25 PM

Users can't afford to be without the database to work, that is for sure.

I know that there are a lot of recovery scenarios, and plans for them... But I was talking about backups... how many, what type of backups, etc.

So far I've been doing ok with daily exports and weekly full backups, just wanted to hear if there is anything else I should be doing,

Saludos,
Veronica Levin Enriquez
Compañía Cervecera de Nicaragua

-----Mensaje original-----

De: Mercadante, Thomas F [mailto:NDATFM_at_labor.state.ny.us] Enviado el: Miércoles, 03 de Octubre de 2001 01:17 p.m. Para: 'ORACLE-L_at_fatcity.com'
CC: Veronica Levin
Asunto: RE: Backup Strategy

Veronica,

Before you can decide on what your backup strategy will be, you really need to talk to the users of your database.

One of the most important pieces of information to get from your users is the "Mean Time to Recovery". Simply put, you ask the user how long they can afford to be without a database.

If they tell you "no more than 10 minutes", then you had better devise and implement an automatic fail-over (either hot-standby, or if you can share the disks, automatic fail-over).

If they tell you "no longer than 1 hour", then you had better make sure that your backup and recovery plan can restore the data files and recover the database within the time frame.

There are probably a dozen different scenarious that you need to consider. Each one will lead to to different types of recovery scenarious. Each one will have a different cost (both in dollars and your time).

hope this helps.

Tom Mercadante
Oracle Certified Professional

-----Original Message-----

Sent: Wednesday, October 03, 2001 2:00 PM To: Multiple recipients of list ORACLE-L

Hi listers,
I was wondering how do you decide your backup strategy.....

I do daily full exports and weekly full backups with database in archivelog mode.
Plus weekly Operating System Backup.

Is this all I can do to ensure fast recovery of the database or server when it is needed?

Any input on this topic will be appreciated!

Saludos,
Veronica Levin Enriquez
Compañía Cervecera de Nicaragua

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Author: Veronica Levin
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Author: George Schlossnagle
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