Typical Performance Results?

[camhabib]

I just finished setting up a three disk software RAID 0 (WD 640GB SE16 drives) and ran XBench to obtain some performance results. I got the following back:

Results 191.34
System Info
Xbench Version 1.3
System Version 10.5.3 (9D34)
Physical RAM 8192 MB
Model MacPro3,1
Drive Type RAID HD
Disk Test 191.34
Sequential 214.90
Uncached Write 360.90 221.59 MB/sec [4K blocks]
Uncached Write 364.39 206.17 MB/sec [256K blocks]
Uncached Read 89.95 26.33 MB/sec [4K blocks]
Uncached Read 504.67 253.64 MB/sec [256K blocks]
Random 172.44
Uncached Write 93.82 9.93 MB/sec [4K blocks]
Uncached Write 654.45 209.51 MB/sec [256K blocks]
Uncached Read 159.74 1.13 MB/sec [4K blocks]
Uncached Read 210.56 39.07 MB/sec [256K blocks]

Is it just me or are some of those numbers alarmingly low? I did set it up with 64K blocks, and it is a software implantation, but should I get numbers like 1.13MB/s? Is there something I'm doing wrong or something that I can try differently? All drives are hooked up internally on a new Mac Pro dual 2.8GHz.