Re: HELP: RAID-5 Killing Performance

Hi:

Without numbers to support this, it's really hard to say. If the CPU utilization looks OK, the memory paging looks OK, and the SGA looks OK, then the problem has to be disk-related. Since the first three are easiest to eliminate, I'd check there first. Look at the V$FILESTAT and at the O/S level for disk statistics. Specifically, look at the I/O requests per second.

On the disk setup, I'd suggest determining if the following would be beneficial: Split disk3 into two seperate disks, and put one set of redo log members on one disk, the Oracle mirrored members on the other. It's very important to mirror the redo logs at the Oracle level rather than the software or hardware level. Only Oracle-level mirroring handles all possible faults, including "stale" redo logs. Move the archive logs to one of the other existing RAID5 arrays. See my site below for RAID info. It's "specific" to NT, but the same rules apply for Solaris. Everything except redo logs are written to in a block-oriented manner, so if you have enough disks in the RAID5 arrays, you can do OK. Again, first determine if disk I/O is actually the problem.

Good luck,

--
David C. Sisk
Need tech info on Oracle? Visit The Unofficial ORACLE on NT site at http://www.ipass.net/~davesisk/oont.htm Like original modern rock? Listen to song samples and buy a CD at http://www.mp3.com/disparityofcult
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In2Home User wrote in message
<937333485.18113.0.pink.d4e11496_at_news.in2home.co.uk>...
>We're running Oracle 8.0.5 on Solaris 2.6.
>Our database server is a Sun UltraSparc I 333MHz with 1GB of RAM.
>We have several disks, a RAID-5 array, and a local tape device.
>
>My DBA is utilizing the disks in the following manner:
>
>disk1 - os
>disk2 - home
>disk3 (mirrored) - archived redo logs
>disk4 (RAID-5) - control file, system, temp, oracle software
>disk5 (RAID-5) - control file, rbs, redo logs
>disk6 (RAID-5) - control file, tools, users, redo logs
>
>My largest concern is that having the redo logs on RAID-5 has
>got to be killing my performance. Ideally, they should be on a
>dedicated set of mirrored drives (then again, ideally I should have
>22 separate disks, yeah). However, my DBA feels that its more
>important to have the archive logs on the dedicated mirrored disks.
>
>Anyone care to share their opinion as to how we might make better
>use of the above hardware setup? Would it make sense to write archive
>logs directly to tape and move the redo logs to the mirrored disks?
>
>Thanks in advance,
>
>Chris
>
>
Received on Tue Sep 14 1999 - 22:13:30 CDT