Several factors can influence the %CPU busy on the FA: -     Read /Write ratio. Writes are more expensive than reads, so maybe the 4 FA's have a higher write rate? -     Array management. Does your Solutions Enabler host(s) use the 4 FA busy FA directors? Commands to the array are processed by the FA's and add to CPU overhead -     Open Replicator migrations -     VAAI operations (SCSI T10 type operations offloaded to the array like extended copy). ESX makes good use of VAAI operations for example.  How far you push the FA's before a performance management intervention is somewhat dependent on how you choose to manage your environment (and how your customers complain about poor performance [IMAGE]). Typically, 70% is considered to be close to the 'knee of the response time curve', where I/O response time starts to increase exponentially. You can obtain / monitor array based FA and device response time metrics to determine if the FA's are too busy. Another excellent metric to review is the FA queuing metrics. Busy FA's mean IO's may need to queue before being executed.  If you have FA's that are under-utilised, it may well be worth considering moving some workload to avoid the performance problem call.
FE director utilization is going high till 65% for 4 adaptors. When I drill down each port on these frontend directors, Port 0 has 174 devices and Port 1 has 17 devices listed. Is the high utilization because of this imbalance, if yes how can reduce it.
FE director utilization is high till 66% for 4 adaptors.