Ben, With that minimal of usage you won't notice the speed difference. So using the 10k's will be fine. As for the cache, it doesn't play a part in the usage. It is in case of a power failure or other hardware issue, the cache will remain to be stored to the array.
Hi, new here. I have 4 36GB 15k rpm HDD in the case now RAID5 on the PERC4/Di, one has failed.  Would like to take the "opportunity" to replace with larger capacity.  I like the end goal of 6 300GB, which should be good for a >long< time.  Had the server for while now and just using at home for personal records and stuff.  A couple websites with not much traffic.  A mySQL server, again if there are more than two users at once that's a big day! :)  I can get the 300GB HDDs in 10 or 15k but the 15k are >$300 where I can pick up used 10k ones for <$80. Please keep in mind, this is mostly a hobby (I get to play IT guy and I'm my only client), my day job is part time welder/fabricator and full time beef farmer.  I justify expenses to the wife that we use the database to keep all our farm records and help with taxes.  So $ is probably the biggest factor, but not the only. 1) So in your experience will I notice much change going from 15k rpm to 10k rpm disks.  2) Also how big of factor does the cache play in my usage of the system?  Is that something I should worry about? Thanks, Ben
expanding storage on PE2600, 300GB10k or 36GB 15k + external