Understand and apply VMFS resignaturing

Use datastore resignaturing if you want to retain the data stored on the VMFS datastore copy.
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.

Procedure

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.

The information for this article was gathered from the ESX Configuration Guide.