Hi, sorry, I don't know much about Vista. However, you need to put your PERC 5/I in a 8x lane PCI-E, otherwise you are limited to under 1GB/sec. Also, you are using 3x HDD in RAID5, which is *effectively* 2x HDD and you're getting 150~200MB/sec so that means each *effective* HDD is doing about 75~100MB/sec!! This is actually very good whenever you can get a SATA hard drive to push close to 100MB/sec, you are close to the limit of your hardware.
If you want something faster, you need to add more HDD. You also may want to move to a 8x lane PCI-E slot though that only matters if you are going to add more HDD.
As to answer your question, though in the context of my Linux server; i set the controller's read cache policy to "NRA", aka "No Read Ahead". Linux has its own read ahead caching mechanism, and doing it twice actually reduces speed by 5~10%. On the other hand, in Linux, i increased the read ahead cache from the default (256K) to 32MB with this command:
# blockdev --setra 32768 /path/to/your/raid/array/block/device
I've experimented with a few values here, from 8MB, 16MB, 32MB, 64MB. Somehow, 32MB seems to yield the best results. 64MB of read ahead cache seems to reduce read throughput of the iozone benchmark. Although I'm happy to have figured this value out, I can't explain *why* this is the best value.
Concerning the PCI-E 4x, I think I wont have a problem with this until I go over 6 hard drives, at the moment 4x bandwidth will be enough and not seeing any typical flat lines in graphs that coincide with bottlenecks.
I am still sure these drives should be running faster, I have seen a few people on here with 3 drive setups getting over 200mb/s, the first page of this thread shows 4x 1TB spinpoints getting ~350MB/sec read on average, this is incredible performance! Would you think that just by adding one more RE2 on to this could yield a huge performance gain? Benchmarking single 500gb RE2's are on par, if not faster than Spinpoint F1's.
The strange thing I have found is if I use no read ahead, the drives average out at about 68MB/sec which is incredibly bad.