I've seen some storage latency on vSphere 5 client event.snapshot is atttaches with this email.please check.
Event: Device naa.7675*********************8787 performance has detoriated.I/O latency increased from average value of 25801
to 32133333 micro seconds.
Note: I've 2 - 850 GB LUNS of iSCSI from netapp FAS 3140 which is mounted on ESXi 5 cluster (7 ESXi 5 HV)
