• A disk appears with the state "Unknown" in the system.
• The issue may affect:
  • A single disk in the system controller (head unit) or attached storage
  • All disks in a newly attached enclosure
  • A disk recently replaced due to failure

A disk may report as "Unknown" due to one of the following reasons:

• A newly installed disk is not (yet) recognized by the system.
• A disk in the system is unreliable (for example, a failed disk reports an 'unknown' state).
• An entire enclosure has been added but not yet integrated into the RAID group.
• A single disk replacement has not been properly initialized.

Follow the steps below based on the scenario:

1. Verify Disk State

   • Use the disk show state command to identify the disk state. Refer to Data Domain: Disk State Descriptions for guidance

2. Single Disk Reports "Unknown" (and is NOT a new replacement disk)

   • Check active system alerts (alerts show current) and disk state (disk show state)
     • If the disk is reported as failed, and is in an 'unknown' state - replace the 'unknown/failed' disk
   • If the 'unknown' disk is a newly installed (replacement) disk, see Step 4.

3. All Disks in a New Enclosure Report "Unknown"

   • This is expected behavior for a newly added shelf.
     • Follow the relevant Shelf Hardware Guide to get the 'Unknown' disks added to storage capacity.
   • A basic overview of the steps to add a new shelf: Obtain relevant licensing, add the storage to the required storage tier (active, cloud) and then expand the filesystem,

4. Single Disk Reports "Unknown" After Replacement

   • Attempt a rescan of drives. Run command # disk rescan
   • Verify status of drive from DD-CLI # disk show state
     • If the disk has become 'In-use' and the alert has not cleared, manually clear the alert using DD-CLI # alerts clear alert-id <alert-id>
     • If the disk remains 'unknown' - run the # disk unfail <encl.disc>  command to transition the disk to a spare state.

5. Need Additional Assistance

   • If the issue remains unresolved:
     • Contact your contracted support provider and raise a service request.