DASD Experts - FIber vs SCSI

Any insights appreciated:

We are converting from SCSI to Fiber on many of our NT and UNIX Oracle servers using a couple of vendor'd dasd. Here is what I am seeing. All DASD is RAID 0+1.

Single SCSI dual port 40mb/s adapter:
- Max Throughput with 1 process - 15 MB/s

• Max Throughput with 2 or more processes - 35 MB/s

2 Load Balanced 100 MB/s Fiber using vendor A's dasd.
- Max Throughput with 1 process - 26 MB/s

• Max Throughput with 2 or more processes - 36 MB/s at 16 processes

2 Load Balanced 100 MB/s Fiber using vendor B's dasd.
- Max Throughput with 1 process - 47 MB/s

• Max Throughput with 2 or more processes - 101 MB/s at 16 processes

Questions:
- Any tricks to make the fiber faster?

• Any watchouts that may make the fiber slower?
• I keep hearing that a bigger block size is better for fiber. Changes in Oracle appear to do little. Also, most of my DBs reads are single block i/o rather than multiblock so performance may go down for some queries.
• It would seem based on this that dual 80 MB/S SCSI would outperform Fiber. Opinions or test results anyone?
• Other comments?

Thanks much......

--
Doug Coan
Oracle Certified Professional DBA


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