Tuning RMAN backup and recovery
- From: "Don Seiler" <don@xxxxxxxxx>
- To: "Oracle-L Freelists" <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 15 Nov 2007 16:53:34 -0600
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
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