Re: Performance of Archive log mode

Further to the other reply, I would suggest that for a large database of this nature, that ARCHIVELOG mode would be required.

With a large capacity, it will be highly unlikely that you could backup the entire database in a single session, while the database is down, which will be required for a cold backup. With ARCHIVELOG enabled databases, backups (hot or cold) do not need to backup the entire database in a single session.

Further, I would expect that some data will not be volatile, and therefore needs to be backed up at a less frequent rate than that of the volatile data. i.e. If you are in a DW environment for Paging or Mobile phone systems, records are added to the current month, but previous months are probably not modified, and therefore these tablespaces could be made Read Only, and once backed up, there is no need to be backed up on a regular basis.

You comment about the downgrade in performance, I would have thought that this should not be a problem. I would expect that the alternate Redo Log Groups would be placed on different disks, and that the Archive Redo Logs would be on another set of disks. Therefore, when a Log Switch occurs, and archival is initiated of the old Redo Log, the Archiver will be accessing one set of disks, and the LGWR will be writing to the other set of disks.

Hope this helps,
Andrew

"CHO, HYON-HYOK" wrote:

> Hi everybody!!
> I engaged in large database.(over 700G - data)
> So I have a headache because of backup policy.
> Oralcle recommended archive log mode, but I
> think archive log mode downgrade the performance seriously,
> through pilot test(especially data warehouse).
> Furthermore,
> Our system has some OLTP features.
> Is there any body who has experience on archive log mode?
> We will use storage-tec archive machine and ORCL RMAN.
Received on Wed Apr 14 1999 - 05:40:20 CDT