Hi
When the ESXi host does not confirm the identity of the LUN with what it expects to see in the VMFS metadata, the snapshot LUNs issue occurs. This issue will occur after replacing SAN hardware or firmware.
To solve the problem, you can add the datastore by using vSphere client. To do this:
In the Hardware panel of Configuration tab, click Storage and then click Add Storage. Select the Disk/LUN storage type and click Next. From the list of LUNs, select the LUN that has a datastore name displayed in the VMFS Label column, then click Next.
Under Mount Options, these options are displayed:
Keep Existing Signature: Persistently mount the LUN (for example, mount LUN across reboots)
Assign a New Signature: Resignature the LUN
Format the disk: Reformat the LUN
You should know that format the disk will delete any existing data on the LUN, so select the proper option
You can check this article VMware Knowledge Base
Hope this could be helpful
