Taken from http://kb.vmware.com/kb/1008205

• Start esxtop by typing ‘esxtop’ at the command line
• Press ‘d’ to switch to disk view (HBA mode.
• Press s, then 2 to alter the update time to every 2 seconds and press Enter.

Now I have used esxtop from time to time and unless you have a good baseline the numbers can be a bit overwhelming.. Now there is a golden nugget of info in this KB article..

“All arrays perform differently, however DAVG/cmd, KAVG/cmd, and GAVG/cmd should not exceed more than 10 milliseconds (ms) for sustained periods of time.”