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Troubleshooting a LUN that is extended in size past the 2TB/2047GB limit
Symptoms
Cannot create VMFS-3 datastore.
The Add Storage wizard may not display devices or LUNs as eligible for creating a VMFS-3 datastore.
Attempting to create a VMFS-3 datastore may fail with the error: Unable to find head extent device path
Existing VMFS-3 datastore is unmounted and no longer mounts.
Guest operating system cannot access an RDM.
Incorrect or inconsistent device or LUN size seen.
Resolution
An ESX/ESXi host is limited to a maximum LUN size of 2047GB. This applies to all LUNs being presented to an ESX Server host (VMFS and RDM). Any capacity larger than the limit is not handled. The LUN may not be presented as a choice for a data store in the Virtual Infrastructure or vSphere Client. Attempting to format the LUN from the Virtual Infrastructure or vSphere Client or command-line generates an error.
A VMFS-3 datastore on a LUN that has been extended past the limit is unmounted. All content on that data store is inaccessible.
Recovery:
Shrink the LUN back to its original size (if possible).
Perform a block copy of the old LUN to a new LUN that is within the size limit.
Destroy the LUN entirely and recreate the LUN within the limit and restore from backup.
