We have a HP Proliant DL380 G9 server. We have a separate data drive which consists of 4 x 1TB 7.2k 6Gb hot-swappable SAS drives RAID 5'd to provide a 3GB logical drive. We've noticed the performance of the server is quite slow and after running various tests I've noticed disk IO on the SQL database isn't very good. I wanted to try and speed it up.
Can anyone answer these questions please: -
(1) As I don't want to rebuild the server from scratch, can I just get 4 identical drives as above but the 12Gb (double the speed) ones and have them running along side-by-side. My plan would be to remove one of the drives from the array, replace it with the faster one, leave it to rebuild, then swap the next one, and the next one, and so on until they are all replaced with the faster ones?
(2) The same scenario as above but replacing the drives, one at a time again, with SSD drives. Can SSD and SAS drives co-exist in the same array? and,
(3) I've noticed there are 15k spindle speed drives, which would improve further the speed, however I can't get a 1TB one only 1.2TB. Can I put a slightly larger drive into a RAID 5 array and it will build OK, or does it have to be an identical size to the others?
Hope this all makes sense. Any help gratefully received.