Looks like you have a lot of writes going on there. Look at the wkB/sec! Massive. Almost no reads at all.<p>Why so many writes? Have you got a lot of small updates and inserts going on? Have you split the transaction log from the data files, preferably on a different disk?<p>Also, put that slow performance logging on a separate disk. In fact, try to turn it off. It can have a performance penalty in its own right!<p>If you want best bang for buck, and you want RAID, it's normally recommended to use RAID 10 (or otherwise known as RAID 1+0). Basically it stripes the data, and then mirrors those stripes. It's the most reliable option.<p>Whatever you do, do NOT use RAID 5, it's just overhead and you telly gain very little in a disk crash due to often lengthy rebuild times.<p>Good luck!