VMware Virtual SAN (vSAN) disk appears as Absent in vSAN Disk Management
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VMware Virtual SAN (vSAN) disk appears as Absent in vSAN Disk Management

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Article ID: 326548

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Updated On:

Products

VMware vSAN

Issue/Introduction

Symptoms:

  • When viewing the vSAN via the Management tab under vSAN | Disk Management, you see a Disk group with a red exclamation diamond and, in the detail window below, it is marked as Absent vSAN Disk.
  • From the command line, when you run this command:

    esxcli vsan storage list

    You see this output for the device:

    Unknown
    Device: Unknown
    Display Name: Unknown
    Is SSD: false
    VSAN UUID: 529a152a-6e87-d8dc-c890-bcfc6fae7669
    VSAN Disk Group UUID:
    VSAN Disk Group Name:
    Used by this host: false
    In CMMDS: false
    Checksum:
    Checksum OK: false



Environment

Vmware vSAN

Cause

This issue occurs due to one or all of these reasons:
  • A physical Disk has failed or been removed from the esxi host .
  • The storage volume was created
  • The storage volume is removed incorrectly

Resolution

To work around this issue, validate if this is a real volume or an empty reference to storage that no longer exists and remove the volume if necessary.
 
To ensure that if it is a real volume and remove the volume if necessary:

Note: Ensure that you have the correct VSAN_UUID before removing the volume that has issue.
  1. Use this command to check if the drive contains any data.

    cmmds-tool find -u VSAN_UUID -f json

    Note: Use the VSAN_UUID reported for the unknown volume by running this command (used under the Symptoms section):

    esxcli vsan storage list
     
  2. If you see an output similar to this, then it indicates that there is no data contained in the storage device:

    {
    "entries":
    [
    ]
    }
     
  3. Use this command to check if any of the vSAN objects claim to have an association with the volume named as VSAN_UUID:

    cmmds-tool find -t DOM_OBJECT -f json |grep VSAN_UUID

    If it provides output to the command line with no data, then it indicates that no objects have data related to VSAN_UUID.
     
  4. After the device is determined to be an empty reference, you can remove it using this command:

    esxcli vsan storage remove -u VSAN_UUID
     
  5. When the command line provides output that it has completed the task successfully, then re-run this command to verify if the listing for this volume is removed:

    esxcli vsan storage list
     
  6. Refresh the view in the Web Client GUI and the volume will also be removed there.
  7. If the command to remove the drive fails with this error:
Unable to remove device: Unable to complete Sysinfo operation. Please see the VMkernel log file for more details.: Sysinfo error: Not found See VMkernel log for details.
  1. Destroy and re-creat the Disk Group that contains the affected disk UUID.
  2. If the command to remove the drive fails with this error:

    Unable to remove device: Cannot remove disk for UUID XXX : storage auto claim mode is enabled

    You can temporarily turn automode off by using this command:

    esxcli vsan storage automode set --enabled=false

    Verify if the setting has changed using this command:

    esxcli vsan storage automode get

    Then re-run this command:

    esxcli vsan storage remove -u VSAN_UUID

    Note: It takes a few moments before the command will run successfully; be patient.

    Verify removal as mentioned in step 5.
     
  3. If needed, turn automode back ON if this is the desired setting in the environment:

    esxcli vsan storage automode set --enabled=true
 


Additional Information

  • The Hardware is identified at BIOS level by the installed firmware on the sever. The SCSI code handling changes from a vendor to vendor and hence some of the vendors may provide the hot swappable HDD option for failed disk
  • However, the ESXi OS requires a reboot of the host to identify the new disk ( hardware changes in the system )  when the existing failed disk is replaced in the same slot to refresh the driver information in ESXi kernel.
  • A newly added disk in the empty slot will be identified in real time. However, this disk replacement and identification behavior changes from vendor to vendor.