Data Domain: Disk State Descriptions

Summary: Descriptions of the various states that a disk drive on a Data Domain system can be in, and the significance of the state.

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Instructions

Disk State Description

PURPOSE

This article lists steps on how to identify what state a disk is reporting and the corresponding action to take.

APPLIES TO

  • All Data Domain (DD) Systems
  • All Data Domain Operating System (DDOS) releases

SOLUTION

  1. Identify the disk state using DD-CLI (SSH) command:
# disk show state
Example Output: 

sysadmin@hostname## disk show state
Enclosure   Disk
             1  2  3  4  5  6  7  8  9  10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
---------   ----------------------------------------------------------------------------
1            .  s  .  .  -  -  -  -
2            .  .  .  s  .  .  .  .  .  .  .  .  .  .  .
3            .  .  .  .  .  .  .  .  .  .  .  .  .  .  s
4            .  .  .  F  .  .  .  .  .  .  .  .  .  .  R
5            .  .  .  .  .  .  .  .  .  .  .  .  .  .  s
6            U  U  U  U  U  U  U  U  U  U  U  U  U  U  U
7            K  K  K  K  K  K  K  K  K  K  K  K  K  K  K
8            .  .  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -
---------   ----------------------------------------------------------------------------

Legend   State                 Count
------   -------------------   -----
.        In Use Disks          60
s        Spare Disks           4
R        Rebuilding Disk       1
U        Unknown Disks         15
K        Known Disks           15
F        Failed Disks          1
-        Not Installed Disks   27
------   -------------------   -----
Total 96 disks
 
Table: Contains Disk State and descriptions with recommended actions
 
STATE SYMBOL DESCRIPTION ACTION
In Use . Disk is assigned to a storage tier and is 'in use'. This status indicates a properly working disk. No action is required.
Spare S The disk is assigned as a hot Spare.  No action is required.
Available V The disk is available for allocation to Active, Archive, Cache, or Cloud tier storage.  A disk becomes 'V' (Available) when a 'U' (Unknown) disk is added as available storage, using the command 
'#storage add tier <tier> enclosure <n>'.
Unknown U The expected state of newly introduced disks Resolving 'Unknown' (U) disks:
- New Single disk (for example, After failed disk replaced)  
# disk unfail n.n
- New Enclosure: 
 # storage add tier <tier> enclosure <n>
- Multiple 'U' disks in existing (in use) enclosures: Contact your Support Provider.
Foreign O Disk is reporting unexpected identification information.
This is encountered during chassis swaps, upgrades, or new shelves being added to an active system.		 Data Domain: Resolving Foreign Disks
Failed F Disk has failed.
Reconstruction of the failed disk is automatically initiated to an available Spare.		 Any Failed disks must be addressed immediately.
Note: Systems that dial home to Dell can auto-create + dispatch a replacement disk.
Check existing Service Requests and if needed. Create a service request .
More info and replacement instructions: See KB Data Domain: Failed, Absent, Unknown, or Powered-off Disk 
Absent A Disk removed or no communication to the inserted disk.
Common causes:
- Disk not firmly seated into slot
- Disk is not detected in DD OS (Data Domain Operating System)
- Faulty disk drive
- Problems with the disk drive controller or slot
ALWAYS allow (at least) 1 minute between removal and insertion of disks. 
Possible troubleshooting steps:
  1. Reseat the disk.
  2. Rescan the disk slot: # disk rescan n.n
  3. Try a 'known-good' disk in the affected slot (for example A Spare from another slot)
  4. Power Cycle the slot (Power off system and attached storage OR Support can reset individual slots on external storage) 
Ref KB: Resolving Disk in "absent" State
Known K Disk(s) in this state are 'Known' by the Operating System (DDOS), but have not been or cannot be assembled properly to form a volume.
Common causes:
- Disk Group (disk enclosure or pack) is missing two or more drives.
- RAID reassemble fails due to excessive errors.
- A bad drive causes path errors on the primary and secondary paths.
- Attempting to add an enclosure to a "live" system.
- Shelves are left uncabled for long periods of time (above 5 minutes).
- A bad SAS cable connection
If multiple disks in an existing system are displayed as 'Known' - Contact your Support Provider to investigate and resolve.
If this has been encountered during installation or upgrade of the DD System, ensure that all cables, controllers, and disks are firmly and securely seated.
- Extra care must be taken when moving SAS interlink cables - always ensure path redundancy.
 Data Domain: Resolving Disk in Known State
Reconstructing R Reconstructing (R) a Failed or Copy Recovery disk to a spare. Data Domain - Understanding Disk Reconstruction
Copy Recovery C The Copy Reconstruction process copies valid data from the marked disk to a Spare disk.
Instead of performing a FULL reconstruction of a failing or marginal disk, we copy existing data from that failing disk to a Spare.
This process is less demanding (with less processing overhead) on the remaining disks within the disk group.		 Allow the Copy Reconstruction to run to completion.
The 'C' disk changes to Failed (F) once the Copy Rebuild is completed.
Replace the Failed (F) disk.
Powered Off P As a proactive measure, DDOS has automatically powered off the disk slot.
Support staff can manually power slots OFF and ON during isolation troubleshooting.		 If the disk was Powered-Off proactively by the system (DDOS), then that disk is encountering underlying issues to avoid impacting other disks and running services.
Gather a Support Bundle and engage your Support Provider to investigate why the slot was Powered off.
This will most likely result in the replacement of the disk.
Once the disk has been replaced, the slot can be powered back on by running the command # disk rescan n.n
- We do NOT recommend powering on the slot without disk replacement or Support engagement.
Exceeded Error Threshold E This disk has exceeded one or more of the disk error thresholds.
DDOS has marked and scheduled the disk to be failed. 		 No action is needed. The system automatically fails the disk (within 24 hours)
System Device Y DDVE-specific system device used for DDOS, logs, cores, and NVRAM No action is needed, is required for DDVE systems.
Not-Installed  - An empty disk slot - not used by the system. This slot may be activated in future upgrades or Licensing. No action is needed.

Additional Information

 

    Affected Products

    Data Domain

    Products

    Data Domain
    Article Properties
    Article Number: 000021916
    Article Type: How To
    Last Modified: 24 Sep 2025
    Version:  6
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