Re: Do I need backup rollback segement tablespace and temporary table ?

A copy of this was sent to "Dong Tang" <tangd_at_ctcdist.com> (if that email address didn't require changing) On Mon, 1 Nov 1999 18:50:13 -0600, you wrote:

>Hi:
>
>Thank you all for responsing my questions.
>
>Let me make myself a little bit clear. I don't want to backup rollback
>segment tablespace and temperary tablesace because I think the data in those
>tablespace is useless during the recovery. Unless I recover the database
>right after I backup those tablespaces. If I don't backup them, even I loss
>all datafiles in those tablespaces, I can create those datafile according to
>information in Control file. And I think it would be much quicker than
>restore datafiles from tape.
>
>I read the manual, I am kinda agree that Frank said. What in the rollback
>segment is recovered from redo log. Otherwise, I have to backup rollback
>segment constantly, as the data in rollback segment is keeping changing.
>

do you want to do cold backups or hot.

if you shutdown normal and cold backup, you could get away without backing up RBS and temp... It would be a bad idea, penny wise/pound foolish in a way.

if you hot backup, you cannot -- you better back RBS up. You have to. No way around it. I've seen sites that didn't -- they lose stuff.

IMO -- during a recovery you are in panic mode. RBS as a percentage of the total database size is not that big. You would really like to have the RBS there as part of the backup just to make it go smoothly. It is the documented procedure, it is the correct way to do it. You want to do it that way. Anything else is just making it more complex, more error prone then it should be.

In Oracle8i, release 8.1, there are truely truely temporary tablespaces with tmpfiles (not datafiles) that you do not backup (even if you do back them up, they are useless).

>Am I right, or having something miss?
>
>Thanks
>
>Dong Tang
>
>
>Frank van Bortel wrote in message <3819E9B5.B22CF3D5_at_vnl.nl>...
>>Jeremiah Wilton wrote:
>>
>>> Pete Sharman wrote:
>>> >
>>> > Theoretically no, but rebuilding the rollback segment tablespace might
>be too
>>> > much of a pain for the gain you get anyway.
>>>
>>> The poster stated that a hot backup is the the backup method. It seems
>>> to me there is no way to have a valid backup of the database withouut
>>> rollback segments. If a recovery were to be attempted without all the
>>> rollback segments available, there would be no way to get the database
>>> open at the end of recovery. Open transactions at the point in time to
>>> which incomplete recovery has been performed would be unavailable for
>>> application to the uncomitted data blocks in the datafiles. The
>>> "emergency" underscore parameters that technically allow a database to
>>> be forced open in these circumstances leave uncommitted data in the data
>>> blocks, which is a semantically and technically undesirable situation.
>>>
>>> As for temporary tablespaces, if they are really of type TEMPORARY, then
>>> they contain no permanent segments and therefore can be easily
>>> re-created after a recovery, so they are not essential elements of a
>>> backup.
>>>
>
>
>

--
See http://osi.oracle.com/~tkyte/ for my columns 'Digging-in to Oracle8i'... Current article is "Part I of V, Autonomous Transactions" updated June 21'st  

Thomas Kyte                   tkyte_at_us.oracle.com
Oracle Service Industries     Reston, VA   USA

Opinions are mine and do not necessarily reflect those of Oracle Corporation Received on Tue Nov 02 1999 - 06:26:03 CST