about the queue length

[Dong Li]

I got a problem when I study the queue length of RAID system. When I used a RAID to simulate a RAID 5 system (with 4 disks), I found the average queue length of the logical driver (RAID driver) was 2.8, the maximum queue length was 614 and the maximum queue time was 4264 ms.

Are they reasonable in real world systems?
How people solve the burstiness problem?

Thanks

Dong

[RBaker · Accepted solution]

Above 2 for average length is not good, increase writeback cache, increase the number of spindles (*2 if possible). Maximum queue time of 4 seconds ... It would be quicker using paper.

[Ted Buis]

What hardware do you have for system and the disk array? What operating system release?
The default scsi queue depth in HP-UX is 8, but the maximum is 256.