Re: Simple hot backup question

"Lucyna Witkowska" <ypwitkow_at_nospamcyf-kr.edu.pl> wrote in message news:bavdm2$n8g$1_at_srv.cyf-kr.edu.pl...
> Hi,
> I have a simple hot backup question.
> When I start backup I do:
> ARCHIVE LOG LIST
>
> Which redolog will be necessary for recovery:
> Oldest online log sequence
> or
> Current log sequence
> I opt for the second.
> Greetings,
> LW

Only the current log is ever unarchived, and therefore only it cannot be sourced from anywhere else. But if you were ever to restore a prior backup, and recover, then the redo contained in the non-current logs will also be required for a complete recovery. If Oracle can't find the online logs (because they no longer exist, for example), then it will use the archived copies instead.

If it can't find the current redo log, then you're toast, and an incomplete recovery is your only option.

To the specific question about *this* particular backup, though. If you restored from *this* backup, then only what is the current redo log, and all and any logs produced after that time, are strictly necessary for recovery purposes... simply because issuing the 'begin backup' command causes a checkpoint to be issued, dirty blocks get flushed to disk for that tablespace, and only transactions from that point on would not be consistently stored in the datafile copy you're about to take.

Regards
HJR Received on Tue May 27 2003 - 07:05:48 CDT