RE: Tuning RMAN backup and recovery

I set out to specifically to test compression performance a few months ago so I changed absolutely nothing other than adding "AS COMPRESSED BACKUPSET" to my BACKUP DATABASE command. I'm backing up to sbt_tape via Netbackup 6.0, but I believe the backups actually go to a disk staging pool rather than directly to a tape drive. I've only tested compression on this one system, so I don't have anything else to compare it to and I'm not sure what would explain why we're seeing different results. It seems to me that the most likely explanation is that my bottleneck is the speed of writes to sbt_tape and those are drastically reduced by the compression so that's where I save the time, whereas you probably are not bottlenecked by the speed of your backup writes to disk so you experience an increase in time due to the extra CPU overhead. Here are my rman configurations:

RMAN> show all;

RMAN configuration parameters are:
CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default CONFIGURE BACKUP OPTIMIZATION ON;
CONFIGURE DEFAULT DEVICE TYPE TO 'SBT_TAPE'; CONFIGURE CONTROLFILE AUTOBACKUP ON;
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE SBT_TAPE TO
'%F'; # default

CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
CONFIGURE DEVICE TYPE 'SBT_TAPE' PARALLELISM 3 BACKUP TYPE TO BACKUPSET; CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE SBT_TAPE TO 1; # default
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE SBT_TAPE TO 1; # default
CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default CONFIGURE CHANNEL DEVICE TYPE 'SBT_TAPE' MAXOPENFILES 1 PARMS
'ENV=(NB_ORA_SCHED=User)';

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
'/opt/oracle/product/10.2/db_1/dbs/snapcf_baandev.f'; # default

-----Original Message-----
From: Limin Guo [mailto:lguo.oracle_at_gmail.com]

Brandon and Robert:

Very interesting to know that it actually save time for you to use RMAN compression than not use it.

Do you use different CONFIGURE when using compression? like channels , parallelization, etc.

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