Hi Guys,

I've been having some arguments with my colleagues about one thing. Always my thought was that as as far as disk performance is concern by looking at the output of the iostat command (AIX) you would be able to identify if you have a hot disk and then by moving some files out that disk or by making sure that the same disk is not share at the array level by another busy application would be good enough and I think it had worked for me for quite a few years. I think according to IBM and I'm saying IBM because we use IBM storage if a disk shows more that 35% time active then it could be be a sign of a performance degradation. Then assuming that I can shift around some files then I might be able to spread the I/O across multiple disks. If so do I still need to go the array level (raid) and check the performance stats (in out case TPC) or the output of the iostat would be more than enough. Basically I would like to know if the output of the iostat is accurate enough to determine if we are suffering a I/O bottleneck or if I still need to check the statistics/performance reports at the array raid level to be sure. Thanks in advance for your comments..