Re: Backup Oracle ? Online Redo Log.

On Mon, 14 Jan 2002, han_at_royal.net wrote:

> Well I thought you kept one cold set and just keep storing
> redo-logfiles forever. Then if your server crashes a year later
> you'd have to apply one year of redo logs. So that isn't the
> case I guess.. And you can use regular operating system
> commands to do the hot backup? A regular copy of all the
> datafiles?

I got corrected on this awhile back. When you think about it, a hot backup is still a cold backup for the tablespace which is offline and being backed up (ie, you still perform an OS level copy to some other destination), but there is block level redo written for that tablespace during the offline state, so the transactions for that tablespace are being written somewhere else. You sort of do a round-robin backup of tablespaces, so in essence, you have a cold backup for each tablespace but at incrementally increasing time frames.

You could do one cold backup and then apply redo from the life of the database as you say, or you can cut the time for recovery down, as well as the need to store all of the archived redo logs by doing hot backups.

-- 
Galen deForest Boyer
Sweet dreams and flying machines in pieces on the ground.