Troubleshooting storage performance issues can be difficult. ESXTOP Command tool can help.
Note: Alway check with your storage vendor for assistance before spending too much time trying to solve storage issues. The differences between NAS, NFS, SAN, iSCSI is enormous and requires expertise.
Command Strings and Switches
I thought I’d post some useful CLI ESXTOP commands to help with monitoring storage for when you start having performance problems resulting from oversubscribed storage.
1. Monitor overall storage performance per HBA:
2. Monitor storage performance per LUN: *
* These options are only available in ESX 3.5 and greater.
The columns we are going to pay attention to are CMDS/s, DAVG/cmd, KAVG/cmd, and GAVG/cmd. Below is a brief description of each of these
This is the number of IOPS or Input/Output Operations Per Second being sent to or coming from the device or VM being monitored.
This is the average response time in milliseconds per command being sent to the device.
This is the amount of time the command spends in the VMkernel.
This is the response time as it is perceived by the guest OS.
For more ESXTOP Commands related to ESXi 4 – 5 please read VMware KB: Using EXSTOP