Re: Tuning RMAN backup and recovery

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

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