Re: Tuning RMAN backup and recovery

From: Robert Freeman <robertgfreeman_at_yahoo.com>
Date: Thu, 15 Nov 2007 19:44:17 -0800 (PST)
Message-ID: <255147.55876.qm@web38904.mail.mud.yahoo.com>

Don a few questions:

What version is this..? Are you using a block tracking file for your incrementals? If not you may be backing up way more information than you need too.
Are you doing your parallel backups to the same disk? You could be running into disk contention if so.
What is your CPU usage during the backup. As mentioned earlier, if you are CPU constrained then compression can slow things down. If you are not CPU constrained then compression can very much speed things up and make your backup images much smaller.

Robert

Don Seiler <don_at_seiler.us> wrote:

> I've read the tahiti doc of (nearly) the same name
> [0], but it really
> didn't do too much. I'm pretty sure I've posted
> about this but it's a
> high priority for me now.
>
> Sad story, short: my level 0 database backups take
> over 7 hours.
> People have mentioned to me that they have databases
> of comparable
> size (or larger) backing up in 1-2 hours. I'm
> equally, if not more,
> interested in reducing the restore/recovery
> (duplication) time, which
> has been around 8-10 hours.
>
> Here's the details of this past weekend's level 0
> database backup,
> from v$rman_backup_job_details:
>
> TIME_TAKEN_DISPLAY: 7:30:47
> INPUT_BYTES_DISPLAY: 1.03T
> OUTPUT_BYTES_DISPLAY: 172.91G
> INPUT_BYTES_PER_SEC_DISPLAY: 39.80M
> OUTPUT_BYTES_PER_SEC_DISPLAY: 6.55M
>
> Here's my configuration:
> RMAN> show all;
>
> RMAN configuration parameters are:
> CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 7
> DAYS;
> CONFIGURE BACKUP OPTIMIZATION ON;
> CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
> CONFIGURE CONTROLFILE AUTOBACKUP ON;
> CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE
> TYPE DISK TO '/rman/%F';
> CONFIGURE DEVICE TYPE DISK PARALLELISM 4 BACKUP TYPE
> TO COMPRESSED BACKUPSET;
> CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE
> DISK TO 1; # default
> CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE
> DISK TO 1; # default
> CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT
> '/rman/%U';
> CONFIGURE MAXSETSIZE TO UNLIMITED; # default
> CONFIGURE ENCRYPTION FOR DATABASE OFF; # default
> CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default
> CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; #
> default
> CONFIGURE SNAPSHOT CONTROLFILE NAME TO
>

'/u00/app/oracle/product/10.2.0/db_1/dbs/snapcf_xcede.f';
> # default
>
> The command script I use for backups is:
>
> SQL "alter session set optimizer_mode=RULE";
> RUN {
> BACKUP INCREMENTAL LEVEL 0 DATABASE;
>
> BACKUP ARCHIVELOG ALL NOT BACKED UP DELETE
> INPUT;
> }
>
> Points of order:
> 1. I'm aware than I can backup the archive logs
> along with the
> database in one single command.
> 2. I set the optimizer_mode based on this blog post.
>

http://www.pythian.com/blogs/363/slow-rman-backups-check-this-out
> .
> As you can see from my overly-enthusiastic comments,
> my tests were
> very favorable. However that didn't seem to
> translate into either
> faster backups or duplications.
> 3. The destination for all backup files is /rman,
> which is a Veritas
> vxfs partition. I'll have to get the physical
> details tomorrow.
>
> [0]
>

http://download.oracle.com/docs/cd/B19306_01/backup.102/b14191/rcmtunin.htm#sthref1057
>
> --
> Don Seiler
> http://seilerwerks.wordpress.com
> ultimate: http://www.mufc.us
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

Robert G. Freeman
Author:
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Received on Thu Nov 15 2007 - 21:44:17 CST