Re: Database Recovery

On Mon, 15 Feb 1999 rprabha_at_my-dejanews.com wrote:

> In a 24X7 environment, a combination of fast restoration of COLD backup
> on tapes coupled with rolling forward the archive logs works out as a
> very workable and practical solution.

In a 24X7 environment, how would you have gotten a cold backup in the first place?

> Also, a HOT backup is a fuzzy backup and thus it would be unwise to
> rely solely upon HOT backups.e.g. When applying redo logs, if one of
> the archive logs turns out to be corrupt, DBA will have to opt for the
> CANCEL based recovery. Thus odds of point in time recovery
> become less than the anticipated perfect score.

But aren't you in the same boat with a cold backup? If you don't want to lose transactions, you have to roll forward through archived redologs to the point your database failed. This is the case with both hot and cold backups. I don't see the disadvantage to hot backups, especially if you have serious high-availability requirements. It is possible to turn on block checksumming on the redologs if you are really worried about redolog corruption, but if you are multiplexing your logs across disks and controllers the chances of that are remote. Why are people so afraid of hot backups?

--
Jeremiah Wilton http://www.wolfenet.com/~jeremiah Received on Sun Feb 14 1999 - 21:46:11 CST