Re: Hot Backups

In article <D7AFun.BvL_at_lanier.com>, Don Vick <dvick_at_lanier.com> wrote:
>But this leaves me wondering why Oracle would recommend against putting
>multiple tablespaces in backup mode at once. The increased data volume on
>the redo's doesn't seem to be much of a problem. Anyone know why they say
>this?

I cant speak for Oracle, But I think they are just being over protective. The extra redo data written to the logs could be a problem in the case of many updates taking place to many different blocks.

The first time a DB block is changed after the tablespace is put in backup mode the Entire block is written. After than only changes to the block are written to the log. So a shop that does small updates to many difference blocks and has large DB blocks sizes could go from very little redo info to a huge amount of redo during a backup.

>BTW, thanks to Lee for correcting my ignorance :-)

I'm sure you'll have the chance to reciprocate in the very near future. :-}

-- 
Regards, 

Lee E. Parsons                  		
Systems Oracle DBA	 			lparsons_at_world.std.com