Data Domain: Disk Unknown

A disk displays the state "Unknown" in the DD-CLI, DDSM, or DDMC.

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

• The system has not yet recognized a newly installed disk.
• A disk is unreliable or failed and reports an unknown state.
• A newly added enclosure has not been integrated into the RAID configuration.
• A replacement disk has not been initialized or transitioned to an active state.

Follow the steps below based on the scenario:

1. Check Your Data Domain Model

   Important: The disk unfail command is not supported on storage pool architecture systems (for example, DD6400). Running this command on these models results in an error.

   • Identify your system model:

     system show modelno
     

   • Use the correct procedure:

     DD6400 (Storage Pool Architecture):

     • Use the storage add command.
     • Refer to: Data Domain DD6400: Adding Replacement Disk on DD6400

     All Other Data Domain Models (Traditional DD-RAID Architecture):

     • Continue with the steps below (disk rescan, disk unfail).

2. Verify Disk State

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

3. 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 it.
   • If the "Unknown" disk is a newly installed (replacement) disk, see Step 5.

4. 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.
       • Overview of the required steps to add a shelf:
         • Apply licensing
         • Add storage to the correct tier (active or cloud)
         • Expand the filesystem

5. Single Disk Reports "Unknown" After Replacement

   • Attempt a rescan of drives. From DD-CLI (ssh), 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.

6. Need Additional Assistance
   Contact your contracted support provider and raise a service request if the issue remains unresolved.

Best Practice: Two-Minute Wait During Disk Swap

• When physically replacing a disk drive, wait at least 2 minutes after removing the failed disk before inserting the new disk.
• This allows the controller firmware to properly deregister the old drive, greatly reducing the possibility of a hotplug issue where the new drive is not properly recognized (showing as "unknown").

Recommended sequence:

1. Remove the failed disk from the slot.
2. Wait two minutes.
3. Insert the new replacement disk.