Robin,
You would get much better performance if you separated the redo log volume
from your data volumes and used RAID-1 rather than RAID-5. There are two
reasons for this. The first reason is that the redo log will be essentially
doing sequential I/O's, which means little head movement on the drives,
therefore those drives can handle more I/O's per second. By having data on the
same volume you will be doing ramdom I/O's, thus you should limit the I/O's to
about 75 I/O's per second per disk. The second reason is that RAID-5 is
inherently slower on writes and writes is what the redo log does. By using
RAID-1 on the redo logs you can achieve higher write performance than RAID-5.
If your system is doing a significant amount of writing you may find yourself
running out of I/O capacity very quickly using RAID-5.
Ed
--
Edward Whalen
President
Performance Tuning Corporation
Database Performance Consultants
Email: ewhalen_at_perftuning.com
Web: www.perftuning.com
Received on Tue Jun 16 1998 - 11:46:17 CDT
