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:
esxcfg-volume -m "vmfs_volume_label"