Does having a system drive connected to a HW RAID controller w/cache increase perf.?

[Paendrag]

Hi.
I own an Adaptec 5805 hardware RAID controller with 512 MB cache, and I am wondering if moving my system drive from the motherboard's integrated controller to the 5805 would increase performance by any meaningfull amount? I would guess that any write operation that fits in available cache would be extremely fast (PCI-E with DDR2 cache should give well over 1 GB/s), but I may be wrong.

Also, does anybody know weather I will be able to keep my current OS install if I do this, or will the HDD have to be deleted when moving it to the 5805?

Thanks for any comments

 

[bexamous]

Yeah write operations will finish instantly sometimes.... like after I download a tvshow or something and then go to extract it... since it was just being dled the rar files are still in systems cache for the most part... so when I hit the extract button the reads are basically instant as well as the writes... the hole operation will appear as though nothing happened. I still sometimes will have to look that the file actually extracted and I didn't hit the wrong button or something because its finishing so fast.

Other times its hard to notice... eg if you just try to copy a large file you have... you still have to wait for the file to be read.... so you don't really notice any big improvement.... although it might be there.

There is also times where it is almost a disadvantage... at least on 3ware controllers... when the cache gets filled the controller all of a sudden seems insanely slow... any io operation just takes forever as it tries to clear out its cache. It'll be wierd too because I'll watch IOs and there will be a spike to 500+MB and then nothing for 10 seconds and then another spike and it'll continue to do this. You would think there would be a spike and then it would go at a constant speed. Anyways while this goes on things feel very laggy. This might be 3ware specific however.

 

[Paendrag]

Just moved my OS drive to the 5805 and all's working fine so far, though it did require a reactivation of Windows Vista.

I have tried filling the cache by transferring large files from several different drives onto my RAID5 (to see if I'll experience the problem you mentioned). The transfer speeds seem to stay pretty constant at a total 140 MB/s to the RAID5, so I'm not sure if I'm actually ever filling the cache entirely.

But the cache is definitely working. HD Tune Pro's file benchmark tops out at about 1 GB/s write speeds to both my system drive and the RAID5.