Data Domain: Failed, Absent, Unknown, or Powered-off Disk

Summary: This article describes how to resolve the condition where a disk drive is in a failed, absent, or powered off state.

This article applies to This article does not apply to This article is not tied to any specific product. Not all product versions are identified in this article.
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Symptoms

You may observe one or more of the following alerts or event codes indicating disk issues:

  • Event Codes: STORAGE-00001, STORAGE-00002, PHYM-00001
  • Alert Messages:
    • Enclosure disk has failed and should be replaced
    • Disk has a hardware fault and may need to be replaced
    • Disk is absent and should be replaced
    • Unable to access the disk; disk state is powered off
    • A disk has failed, and the enclosure slot has been disabled

Affected Products:

  • All Data Domain systems
  • All Data Domain Operating System (DDOS) software releases

Cause

DDOS continuously monitors disk health and automatically fails a drive when critical I/O errors occur.

Alerts are generated when a disk is:

  • Removed (absent)
  • Dead or failed
  • Powered off (manually or automatically by DDOS to prevent backend issues)

Resolution

Verify and confirm the failure:

  1. Verify the alerts on the system using DDMC, Data Domain System Manager (DDSM) Web UI, or DD-CLI (SSH).
    • DD-CLI # alerts show current
    • DDSM > Alerts 
  1. Identify and confirm the current state of all drives in the system.
    • DD-CLI # disk show state | AND | # disk show hardware
    • DDSM > Hardware > Storage > Disks 
    • Single failed disks should be replaced immediately.
      • Contact your support provider and raise a service request (SR) if an SR has not been raised automatically.
    • If multiple disk drive alerts exist, contact your contracted support provider for assistance with the next steps.

Example: DD-CLI:

sysadmin@DD# disk show state
Enclosure   Disk
             1  2  3  4  5  6  7  8  9  10 11 12 13 14 15
---------   ----------------------------------------------
1            .  .  .
2            .  .  .  .  .  .  .  .  .  .  .  .  .  .  s
3            .  .  .  .  .  .  .  .  .  .  .  .  .  .  s
4            .  .  .  .  .  .  .  .  .  .  .  .  .  .  s
5            .  .  .  .  .  F  .  .  .  .  .  .  .  .  R
6            .  .  .  .  .  .  .  .  .  .  .  .  .  .  s
---------   ----------------------------------------------

Replace the failed disk:

  1. See relevant documented disk replacement procedures (Data Domain Documentation
    • Tip: Best practice for replacing disk drives should include a one minute waiting period from the time a drive is removed until the new drive is inserted.
    • For example, remove the failed disk, wait one minute and then insert the new disk.
    • This allows the controller firmware to properly remove the old drive before the new drive is inserted, greatly reducing the possibility of a hotplug issue where the new drive is not properly recognized.
  2. Verify that the drive is in a SPARE state after replacement.
    • From DD-CLI # disk show state
    • DDSM > Hardware > Storage > Disks 

Example: DD-CLI:

sysadmin@DD# disk show state
Enclosure   Disk
             1  2  3  4  5  6  7  8  9  10 11 12 13 14 15
---------   ----------------------------------------------
1            .  .  .
2            .  .  .  .  .  .  .  .  .  .  .  .  .  .  s
3            .  .  .  .  .  .  .  .  .  .  .  .  .  .  s
4            .  .  .  .  .  .  .  .  .  .  .  .  .  .  s
5            .  .  .  .  .  s  .  .  .  .  .  .  .  .  .
6            .  .  .  .  .  .  .  .  .  .  .  .  .  .  s
---------   ----------------------------------------------
  • The newly installed disk becomes (S)pare and the reconstructed disk is now 'in-use'.

If the new drive reports as Unknown:

  1. Attempt a rescan of the drives. Run command # disk rescan
  2. Verify status of drive from DD-CLI # disk show state
  3. Clear the alert for unknown drive from DD-CLI # alerts clear alert-id <alert-id>

If the new drive reports as failed after a drive replacement:

  1. Attempt to rescan the drive by rescanning one or more drives. Run command # disk rescan
  2. Verify status of drive from DD-CLI # disk show state
  3. If the drive is still shown as (F)ailed, run this command from DD-CLI: # disk unfail <encl.disc>

For example: # disk unfail 5.6

Clearing the drive alert after drive replacement:

  1. Clear the alert for the unknown drive from DD-CLI # alerts clear alert-id <alert-id>

PowerProtect DD - Replacing Cache Tier Disk on DD6900/DD9400

Duration: 00:02:09 (hh:mm:ss)
Closed captions: None available


PowerProtect DD - Replacing Cache Tier Disk on DD9900

Duration: 00:02:13 (hh:mm:ss)
Closed captions: None available


Reference:

    Affected Products

    Data Domain
    Article Properties
    Article Number: 000043773
    Article Type: Solution
    Last Modified: 05 Jun 2026
    Version:  16
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