So we just put in a new Compellent SC4020 SAN and i'm noticing that occasionally ESXi (5.5) is reporting crazy latency like anywhere from 300 to 1000+ms under performance/datastore but on the SAN side i'm seeing an average of 1-2ms (max 10) latency for the same LUN when doing large file copies or lots of small copies. I'm running 10gb to the SAN with jumbo frames, vmkping shows good connectivity with the jumbo frames and i'm not seeing any CPU spikes or anything on either the SAN or host side (when I had latency issues with my old NetApp is was usually because of CPU). Running esxtop is showing the same numbers i'm seeing via the GUI, but I guess I shouldn't be surprised there. I don't see any crazy high numbers for retransmits on the switch (Dell MXL 10/40) and no CPU or other obvious issues jumping out there. The experience within the VMs themselves seems to be just fine, so i'm not sure if there is an actual problem. Is it possible that ESX is just not reporting the numbers properly or is there something else I need to look at?
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