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 UUID and a new label to the copy, and mounts the copy as a datastore distinct from the original.

The default format of the new label assigned to the datastore is snap-snapID-oldLabel, where snapID is an integer and oldLabel is the label of the original datastore.

When you perform datastore resignaturing, consider the following points:

  • Datastore resignaturing is irreversible.
  • The LUN copy that contains the VMFS datastore that you resignature is no longer treated as a LUN copy.
  • A spanned datastore can be resignatured only if all its extents are online.
  • The resignaturing process is crash and fault tolerant. If the process is interrupted, you can resume it later.
  • You can mount the new VMFS datastore without a risk of its UUID colliding with UUIDs of any other datastore, such as an ancestor or child in a hierarchy of LUN snapshots.


To resignature a mounted datastore copy, first unmount it.

Before you resignature a VMFS datastore, perform a storage rescan on your host so that the host updates its view of LUNs presented to it and discovers any LUN copies.


  1. Log in to the vSphere Client and select the server from the inventory panel.
  2. Click the Configuration tab and click Storage in the Hardware panel.
  3. Click Add Storage.
  4. Select the Disk/LUN storage type and click Next.
  5. From the list of LUNs, select the LUN that has a datastore name displayed in the VMFS Label column and click Next.
    The name present in the VMFS Label column indicates that the LUN is a copy that contains a copy of an existing VMFS datastore.
  6. Under Mount Options, select Assign a New Signature and click Next.
  7. In the Ready to Complete page, review the datastore configuration information and click Finish.

What to do next

After resignaturing, you might have to do the following:

  • If the resignatured datastore contains virtual machines, update references to the original VMFS datastore in the virtual machine files, including .vmx, .vmdk, .vmsd, and .vmsn.
  • To power on virtual machines, register them with vCenter Server.