VMware ESX Guest OS I/O Timeout Settings for NetApp

I’ve had a few Windows machines crash due to disk timeouts. I don’t feel as though this should happen as the guest’s are on local storage but it does! Here’s NetApp’s recommended fix.

Installation:

In your Windows Guest OS, copy the lines below into a new Notepad file (Start > All Programs > Accessories > Notepad). Note: Make sure the last line is a blank line, otherwise the registry merge won’t work.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesDisk]
“TimeoutValue”=dword:000000be

Name the file as windows_gos_timeout.reg

Change the “Save as Type” to “All Files” and save it to your Desktop

Right click the file and select Merge

The following dialogue box is displayed:

Are you sure you want to add the information in [path of .reg file] to the registry?

If you click Yes, you receive the following message:

Information in [path of .reg] file has been successfully entered into the registry.

ESXTOP and troubleshoot latency on an ISCSI network

Run esxtop on the console or putty session by typing in ‘ESXTOP’
Press ‘U’ to bring up the disks/LUN’s attached to the host
Now type ‘F’ to display field to add/remove
Now type ‘H’ to enable ‘LATSTATS = Latency stats (ms)’.  You will see a star appear to the left hand side of the line.  Once you see the star press ‘enter’.
Look for the column labelled DAVG/cmd.  This figure should be below 100 but I have seen this recently at 2000 which is really bad!