Host Not Recognising Datastore

I’ve come across this issue on a couple of occasions and thought that I would share with people one of the easiest ways to resolve it.

A summary of the issue is as follows:

You have presented up a LUN that may have been previously presented to another host and when you go through the vCenter GUI or Web Client to add in the datastore (selecting the ‘Keep Existing Signature’ option), the command appears to complete successfully but the datastore does not appear in the GUI.

The simplest way I have found to resolve this issue is to follow these steps:

• Enable SSH on the host that is experiencing this problem
• Log onto the host using Putty
• Type the following:

esxcfg-volume -l

• This will now provide you with a list of the datastores that can be mounted but aren’t currently showing on that host
• Make a note of the vmfs label name as you will need it in a minute, next type:

esxcfg-volume -m "vmfs_volume_label"

• You can now disconnect from putty
• Go back to the GUI or web client and rescan the storage and the missing datastore should now appear.
• Repeat the process on any other hosts or datastores that are also experiencing the same issue.