Re: Tuning RMAN backup and recovery

What are the disk stats during the backups (from iostat)? Some things I would investigate:

- are the target drives saturated?
- are the I/O channels saturated?
- do /rman and the db file luns share physical spindles? (hopefully not)

I would suggest that you should have N luns where N is the number of parallel streams. This allows N I/O SCSI queues to be simultaneously serviced vs. one. Think of this like more check out lanes at the grocery store.

Compression has the CPU overhead, but reduces the IO bandwidth and storage space requirement. If you are not I/O bound (or space) then it won't provide any visible performance gains - it will just consume more CPU. It's basically a trade off.

Ultimately you want the target writes to be the bottleneck, but operating at optimal efficiency.

On 11/15/07, Don Seiler <don_at_seiler.us> wrote:
> Some quick answers to these questions before I hop into bed.

-- 
Regards,

Greg Rahn
http://structureddata.org
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