I got to say that’s a real great tool. However I must mention a weird problem I ran into using that tool :

When doing Storage vMotions on ESXi hosts (5.1 U2) and looking at “Disk World” stats on the ESXi host who was running the storage vmotion, the host will get disconnected from vCenter near the end of completion of the task (At the state where the ESXi host do some local disk I/O).

This problem did not happened all the time. Most often the problem has been seen on VMs that were more than 100-150 GB.

I was able to reproduce this error on 3 different machine types. All of my environment was checked and upgraded : last firmwares on servers, HDDs, SANs, and fiber switches. Also, most recent drivers were installed on ESXi hosts. Nothing did resolve my problem until I quit looking at my live “Disks stats” with visualEsxtop when doing storage vmotions.

Note : I was using the “visualesxtop.zip” downloaded before march 2014. I know that after March 5th 2014, the “vtop-core.jar” was modified and one line was added in the included file “StatsParser.class”, who was about a certain “wPerDevQueueDepth”.

Thanks,

Nicolas