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

On Sun, 26 Aug 2001 22:32:45 -0700, "Sean Fitzgerald" <sfitzgerald_at_centurytel.net> wrote:

>> 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.

OK, I see that archived logs and online logs are secured by multiplexity, not by backup. I still don't understand why these tablespaces can be backed up at different times.

Let's say data1.ora, data2.ora, data3.ora are three datafiles and belong to ts1, ts2, ts3 tablespaces, on-line backup are performed at t1, t2, t3 when SCNs are n1, n2, n3. t1<t2<t3, thus n1<n2<n3. Now that the instance fails (say t4), I copy datafiles back to where they were, and start the instance with the current (t4) controlfile, archived logs, and online logs, Oracle will be brought back to the state of t4?

>snip

Dino Received on Mon Aug 27 2001 - 00:17:51 CDT