QUESTION :
I am a bit confused on the disk queue length value that I get in perfmon, I have 10 physical spindles running raid 5 and the current disk queue length hits 0.24. Should I start worrying once it goes to 20.00?
ANSWER :
Not knowing the further specifics, I would speculate that the RAID5 Array should be transparent to the OS or at least the performance monitor, which would mean that for you anything over 1 is less than desirable, 2 would be slow drives. It should be looked upon as a single drive for this type of performance measurement. As such 0.24 is fine, but personally I’d like my drives to average a bit lower than that.