6.7

What to do next
After you create the Virtual Volumes datastore, you can perform such datastore operations as renaming
the datastore, browsing datastore files, unmounting the datastore, and so on.
You cannot add the Virtual Volumes datastore to a datastore cluster.
Managing Duplicate VMFS Datastores
When a storage device contains a VMFS datastore copy, you can mount the datastore with the existing
signature or assign a new signature.
Each VMFS datastore created in a storage disk has a unique signature, also called UUID, that is stored in
the file system superblock. When the storage disk is replicated or its snapshot is taken on the storage
side, the resulting disk copy is identical, byte-for-byte, with the original disk. For example, if the original
storage device contains a VMFS datastore with UUIDX, the disk copy appears to contain a datastore
copy with the same UUIDX.
In addition to LUN snapshots and replications, certain device operations, such as LUN ID changes, might
produce a copy of the original datastore.
ESXi can detect the VMFS datastore copy. You can mount the datastore copy with its original UUID or
change the UUID. The process of changing the UUID is called the datastore resignaturing.
Whether you select resignaturing or mounting without resignaturing depends on how the LUNs are
masked in the storage environment. If your hosts can see both copies of the LUN, then resignaturing is
the optimal method.
Keeping Existing Datastore Signature
If you do not need to resignature a VMFS datastore copy, you can mount it without changing its signature.
You can keep the signature if, for example, you maintain synchronized copies of virtual machines at a
secondary site as part of a disaster recovery plan. In the event of a disaster at the primary site, you mount
the datastore copy and power on the virtual machines at the secondary site.
Resignaturing a VMFS Datastore Copy
Use datastore resignaturing if you want to retain the data stored on the VMFS datastore copy.
When resignaturing a VMFS copy, ESXi assigns a new signature (UUID) to the copy, and mounts the
copy as a datastore distinct from the original. All references to the original signature in virtual machine
configuration files are updated.
When you perform datastore resignaturing, consider the following points:
n
Datastore resignaturing is irreversible.
n
After resignaturing, the storage device replica that contained the VMFS copy is no longer treated as a
replica.
n
A spanned datastore can be resignatured only if all its extents are online.
vSphere Storage
VMware, Inc. 181