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Home -> Community -> Usenet -> c.d.o.server -> Re: Oracle Performance on RAID 5
Robert
With RAID 5 you will definately suffer on writes, but reads in general
perform well on RAID 5. This has to do with how the parity is
calculated and written to the drives. On a read, the controller simply
reads the data off of the drive where it resides, therefore you can
achieve the performance that you would expect from the number of drives
that you have. For writes the parity is calculated by reading the data
and parity stripes, computing the new parity and xoring in the new data
and then writing them both back out. Thus, a logical write incurs 4
physical I/O's. In keeping with apx 70 random I/O's per second per disk
drive you can see how your capacity can be reduced.
Ed
--
Edward Whalen
President
Performance Tuning Corporation
Database Performance Consultants
Email: ewhalen_at_perftuning.com
Web: www.perftuning.com
Received on Thu Jun 11 1998 - 12:25:20 CDT
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