Re: Why is on-line backup one tablespace a time?

> Do you mean that the backup of datafiles + online redo logs will do
> for recovery even there are time-difference among the backed-up
> tablespaces?

You don't back up online redo logs. If you did and you restored them you would lose any transactions in the current logs. This is why you need to have multiple members in each redo group and have your disk drives mirrored. You don't want to lose your online logs.

 In terms of transaction management or SCNs, please
> explain why this is recoverable?

This is the basics of any recovery. An old file is restored and the archived logs + online logs bring the datafile back to the current SCN.

 On the other hand, as long as redo
> logs are not backed up, the database is still unrecoverable. How can
> redo logs be backuped up without the instance down?

Again, don't backup online logs.

> (In the controlfile case, 'alter database backup controlfile' will do
on-line
> backups)
>

this will make a backup of your control file but can only be used in special recoveries where you will
need to open the database with the reset logs option. This is normally a "last resort".

> One practical question: do you do this in batch with a script or do it
> interactively? Thanks again.
>

I would do it in a script. DBA's usually have something better to do than take manual backups. Received on Mon Aug 27 2001 - 00:32:45 CDT