Perc 5 SATA vs SAS

[Collins, Kevin L.]

I purchased a PE1950 almost a month ago to become a VMware server
hosting 4 virtual machines.  I purchased it with the Perc 5/i and
2x750GB SATA 3.5" drives in RAID1.  Almost immediately, I noticed a
bottleneck with Disk Throughput.  So this weekend, I put the machine
through some tests.  What I found was that with every tweak that I knew,
I could only achieve ~28 MB/sec for sequential writes and ~52 MB/sec for
sequential reads.  (I have bonnie++ stats if anyone is interested.)

As you can imagine, this is unacceptable for my needs.  (I've got a
4-port 3Ware ATA-100 RAID card that will double that throughput in RAID
1)

So I'm left with three choices:

- Swap the SATA drives for SAS.  (gaining throughput from ATA vs SCSI
and 7200 RPM vs 10,000/15000 RPM spindle speeds)
- Swap the 2x3.5" chassis for the 4x2.5" chassis and go with SAS.
- Swap the whole machine in for a 2950.

I'd like to do as much as I can in as little time as I can for as little
money as I can.  My goal is to achieve above 100 MB/sec for reads and
very close to that for writes.

So I'm calling on anyone on the list that might have a PowerEdge w/SAS
and the Perc 5 in RAID 1 that could give me some numbers for comparison.
(I've found that using a quick 'dd' to create a 1GB file is very close
to the bonnie++ numbers, so that'll work for me too - I just want a
general idea of the difference.)

I also would like to hear people's opinion of the 2.5" drives as well
(as I prefer the 1U form factor of the machine).

(The 2950 gives me nothing other than access to more spindles.  And at
nearly twice the price in my configuration, I'll keep that as a very
last resort.)

Thanks in advance...



Kevin L. Collins, MCSE
Systems Manager

nesbitt engineering, inc.
227 North Upper Street
Lexington, KY. 40507

Direct Line: 859.685.4524
Cell:        859.317.1501