Re: Tuning RMAN backup and recovery

From: Robert Freeman <robertgfreeman_at_yahoo.com>
Date: Thu, 15 Nov 2007 19:41:13 -0800 (PST)
Message-ID: <959932.52956.qm@web38914.mail.mud.yahoo.com>

IF you are CPU constrained then compression can be a problem. However, IF you are NOT CPU constrained then Compression of the backup to disk can and will reduce the size of your backups.

RF
--- krish.hariharan_at_quasardb.com wrote:

> Don,
>
> My experience is with VLDB (30TB) rman backups going
> directly to tape
> (disk cache) averaging 1G/channel-min. However, I am
> curious about the
> following
>
> CONFIGURE DEVICE TYPE DISK PARALLELISM 4 BACKUP TYPE
> TO COMPRESSED BACKUPSET
>
> I did a benchmark with CAS technology based RMAN
> backup and the limiting
> factor was CPU not Disk IO. My gut feel is that you
> may be CPU bound based
> on the ratio of bytes read per sec to bytes written
> per sec, due to backup
> set compression.
>
> Can you benchmark a smaller backup (couple of files)
> with and without
> backupset compression?
>
> The alternative if you want to use compressed backup
> sets, if you are
> thread constrained but not CPU constrained, and
> should CPU be your
> bottleneck, is to increase the number of channels to
> the extent your disk
> subsystem would allow, to meet your SLA target.
>
> If on the other hand you are disk constrained, which
> I suspect you are
> not, then you may be able to speed up by using ASM
> or direct io options
> (if not already set) and should the underlying
> array/disk has io head
> room.
>
> -Krish
>
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

Robert G. Freeman
Author:
Now Available for Pre-Sales on Amazon.com!!!!

Oracle Database 11g New Features (Oracle Press)

Portable DBA: Oracle (Oracle Press)
Oracle Database 10g New Features (Oracle Press) Oracle9i RMAN Backup and Recovery (Oracle Press) Oracle9i New Feature
Blog: http://robertgfreeman.blogspot.com (Oracle Press)

--
http://www.freelists.org/webpage/oracle-l

Received on Thu Nov 15 2007 - 21:41:13 CST