Some environments maintain copies of the production LUNs as a backup, by replicating them. These replicas are exact copies of the LUNs that were already presented to the ESXi hosts. If for any reason a replicated LUN is presented to an ESXi host, then the host will not mount the VMFS volume on the LUN. This is a precaution to prevent data corruption.
You can, however, force mount such a volume, but you need to make sure that the original LUN is unpresented.
The act of mounting a snapshot volume can be done in two ways:
The following procedure will guide you through the steps required to mount a VMFS volume ...