How to detach a LUN device from ESXi hosts
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How to detach a LUN device from ESXi hosts

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Article ID: 323128

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Updated On:

Products

VMware vSphere ESXi

Issue/Introduction

This article provides steps to unmount a LUN from an ESXi 6.x/7.x host, which includes unmounting the file system and detaching the datastore/storage device. These steps must be performed for each ESXi host.

Note: The documented method using the vSphere Client is limited to detaching the device on a per-host basis. To detach a storage device from multiple hosts at the same time, see Automating detaching datastores using PowerCLI and the vSphere SDK for Perl in the Resolution section in this article.

Symptoms:
  • A datastore cannot be unmounted using the vSphere Client.
  • The following error is reported:

    Cannot unmount volume Datastore_details because Reason. Correct the problem and retry the operation.

    Where reason can be any of these:
     
    • One or more virtual machines are still registered on it
    • Swap to host cache is enabled on it
    • Storage I/O Control is either enabled or running in statistics collection mode on it
    • File system is busy


Environment

VMware vSphere ESXi 6.5
VMware vSphere ESXi 6.7
VMware vSphere ESXi 7.x
VMware vSphere ESXi 8.x

Resolution

Pre-unmount checklist

  • If the LUN is being used as a VMFS datastore, all objects (for example, virtual machines, templates, and Snapshots) stored on the VMFS datastore must be unregistered or moved to another datastore.
  • All CD/DVD images located on the VMFS datastore must also be unmounted/unregistered from the virtual machines.
  • The datastore is not used for vSphere HA heartbeat.
  • The datastore is not part of a datastore cluster.
  • The datastore is not managed by Storage DRS.
  • The datastore is not configured as a diagnostic coredump Partition/File and Scratch Partition. For more information, see the following:
  • Storage I/O Control is disabled for the datastore.
  • No third-party scripts or utilities running on the ESXi host can access the LUN that has issue. If the LUN is being used as a datastore, unregister all objects (such as virtual machines and templates) stored on the datastore.
  • If the LUN is being used as an RDM, remove the RDM from the virtual machine. Click Edit Settings, highlight the RDM hard disk, and click Remove. Select Delete from disk if it is not selected and click OK.

    Note: This destroys the mapping file but not the LUN content.
  • Check that there are no processes locking the VMFS with this command: esxcli storage core device world list -d
For example:
[root@esxi:~] esxcli storage core device world list -d naa.6589cfc000000080160d5180d713aae5
Device                                World ID  Open Count  World Name
------------------------------------  --------  ----------  ------------
naa.6589cfc000000080160d5180d713aae5     65575           1  idle0
naa.6589cfc000000080160d5180d713aae5     67003           1  sdrsInjector
naa.6589cfc000000080160d5180d713aae5     67080           1  storageRM


 Check if the LUN/datastore is used as the persistent scratch location for the host. For more information on persistent scratch, see Creating a persistent scratch location for ESXi 8.x/7.x/6.x (broadcom.com).

Note: When using the vSphere Client with vSphere 6.x and later, only these checks are performed during the datastore unmount operation:
  • Host should not have any virtual machines residing on this datastore
  • Host should not use the datastore for HA heartbeats



Obtaining the NAA ID of the LUN to be removed

From the vSphere Client

This information is visible in the Properties window of the datastore.

From the ESXi host

Run this command:
esxcli storage vmfs extent list

For example:

esxcli storage vmfs extent list
Volume Name VMFS UUID Extent Number Device Name Partition
----------- ----------------------------------- ------------- ------------------------------------ ---------
datastore1 4de4cb24-4cff750f-85f5-0019b9f1ecf6 0 naa.6001c230d8abfe000ff76c198ddbc13e 3
Storage2 4c5fbff6-f4069088-af4f-0019b9f1ecf4 0 naa.6001c230d8abfe000ff76c2e7384fc9a 1
Storage4 4c5fc023-ea0d4203-8517-0019b9f1ecf4 0 naa.6001c230d8abfe000ff76c51486715db 1
LUN01 4e414917-a8d75514-6bae-0019b9f1ecf4 0 naa.60a98000572d54724a34655733506751 1

Make a note of the NAA ID of the datastore to use this information later in this procedure.

Note: Alternatively, run the esxcli storage filesystem list command, which lists all file systems recognized by the ESXi host.



Unmount and Detach a LUN using the vSphere Client

Note: These steps to not apply to the vSphere Web Client or HTML5 client.

To unmount a LUN from an ESXi host using the vSphere Client:

  1. If the LUN is an RDM, continue on step 2. Otherwise, in the Configuration tab of the ESXi host, click Storage. Right-click the datastore being removed and click Unmount.

    A Confirm Datastore Unmount window appears. When the prerequisite criteria have been passed, click OK.
     
  2. Select a ESXi host and click the Storage view under Configure > Storage Devices:



    Note: Screenshot below is from a HTML5 vSphere Client environment.
     
  3. Right-click the NAA ID of the LUN (as noted above) and click Detach. A Confirm Device Unmount window is displayed. When the prerequisite criteria are passed, click OK. Under the Operational State of the Device, the LUN is listed as Unmounted.

    Note: The Detach function must be performed on a per-host basis and does not propagate to other hosts in vCenter Server. If a LUN is presented to an initiator group or storage group on the SAN, the Detach function must be performed on every host in that initiator group before unmapping the LUN from the group on the SAN. Failing to follow this step results in an all-paths-down (APD) state for those hosts in the storage group on which Detach was not performed for the LUN being unmapped.
     
  4. Confirm if the LUN is successfully detached. The LUN can then be safely removed from the SAN. For more information, contact your storage array vendor.
  5. Perform a rescan on all ESXi hosts which had visibility to the LUN. The device is automatically removed from the Storage Adapters.
Note: If trying to unmount a LUN from a software iscsi based storage array see the the vSphere Documentation page before rescanning. 
 

When the device is detached, it stays in an unmounted state even if the device is re-presented (that is, the detached state is persistent). To bring the device back online, the device must be attached.

To permanently decommission the device from an ESXi host, manually remove the NAA entries from the host configuration:

  1. To list the permanently detached devices, run this command:

    esxcli storage core device detached list

    Output will be similar to:

    Device UID State
    ------------------------------------ -----
    naa.50060160c46036df50060160c46036df off
    naa.6006016094602800c8e3e1c5d3c8e011 off
     
  2. To permanently remove the device configuration information from the system, run this command:

    esxcli storage core device detached remove -d NAA_ID

    For example:

    esxcli storage core device detached remove -d naa.50060160c46036df50060160c46036df

Unmount and Detach a LUN using the command line

To unmount a LUN from an ESXi 6.x/7.x host using the command line:

  1. If the LUN is an RDM, skip to step 4. Otherwise, to obtain a list of all datastores mounted to an ESXi host, run this command:

    esxcli storage filesystem list

    The output which will list all VMFS datastores, will be similar to:

    Mount Point Volume Name UUID Mounted Type Size Free
    ------------------------------------------------- ----------- ----------------------------------- ------- ------ ----------- -----------
    /vmfs/volumes/4de4cb24-4cff750f-85f5-0019b9f1ecf6 datastore1 4de4cb24-4cff750f-85f5-0019b9f1ecf6 true VMFS-5 140660178944 94577360896
    /vmfs/volumes/4c5fbff6-f4069088-af4f-0019b9f1ecf4 Storage2 4c5fbff6-f4069088-af4f-0019b9f1ecf4 true VMFS-3 146028888064 7968129024
    /vmfs/volumes/4c5fc023-ea0d4203-8517-0019b9f1ecf4 Storage4 4c5fc023-ea0d4203-8517-0019b9f1ecf4 true VMFS-3 146028888064 121057050624
    /vmfs/volumes/4e414917-a8d75514-6bae-0019b9f1ecf4 LUN01 4e414917-a8d75514-6bae-0019b9f1ecf4 true VMFS-5 146028888064 4266131456

     
  2. To find the unique identifier of the LUN housing the datastore to be removed, run this command:

    esxcfg-scsidevs -m

    This command generates a list of VMFS datastore volumes and their related unique identifiers. Make a note of the unique identifier (NAA_ID) for the datastore to be unmounted as this will be used later on.

    For more information on the esxcfg-scsidevs command, see Identifying disks when working with VMware ESXi (broadcom.com) .


  3. Unmount the datastore by running this command:

    esxcli storage filesystem unmount [-u UUID | -l label | -p path ]

    For example, use one of these commands to unmount the LUN01 datastore:

    esxcli storage filesystem unmount -l LUN01
    esxcli storage filesystem unmount -u 4e414917-a8d75514-6bae-0019b9f1ecf4
    esxcli storage filesystem unmount -p /vmfs/volumes/4e414917-a8d75514-6bae-0019b9f1ecf4

    Note: If the VMFS filesystem to be unmounted has active I/O or has not fulfilled the prerequisites to unmount the VMFS datastore, an error will be seen in the vmkernel logs similar to:

    WARNING: VC: 637: unmounting opened volume ('4e414917-a8d75514-6bae-0019b9f1ecf4' 'LUN01') is not allowed.
    VC: 802: Unmount VMFS volume f530 28 2 4e414917a8d7551419006bae f4ecf19b 4 1 0 0 0 0 0 : Busy
     
  4. To verify that the datastore is unmounted, run this command:

    esxcli storage filesystem list

    Output will be similar to: 

    Mount Point Volume Name UUID Mounted Type Size Free
    ------------------------------------------------- ----------- ----------------------------------- ------- ------ ----------- -----------
    /vmfs/volumes/4de4cb24-4cff750f-85f5-0019b9f1ecf6 datastore1 4de4cb24-4cff750f-85f5-0019b9f1ecf6 true VMFS-5 140660178944 94577360896
    /vmfs/volumes/4c5fbff6-f4069088-af4f-0019b9f1ecf4 Storage2 4c5fbff6-f4069088-af4f-0019b9f1ecf4 true VMFS-3 146028888064 7968129024
    /vmfs/volumes/4c5fc023-ea0d4203-8517-0019b9f1ecf4 Storage4 4c5fc023-ea0d4203-8517-0019b9f1ecf4 true VMFS-3 146028888064 121057050624
    LUN01 4e414917-a8d75514-6bae-0019b9f1ecf4 false VMFS-unknown version 0 0

    The Mounted field is set to false, the Type field is set to VMFS-unknown version, and that no Mount Point exists.

    Note: The unmounted state of the VMFS datastore persists across reboots. This is the default behavior. To unmount a datastore temporarily, do so by appending the --no-persist flag to the unmount command.
     
  5. To detach the device/LUN, run this command:

    esxcli storage core device set --state=off -d NAA_ID
     
  6. To verify that the device is offline, run this command:

    esxcli storage core device list -d NAA_ID

    The output, which shows that the Status of the disk is off, will be similar to:

    naa.60a98000572d54724a34655733506751
    Display Name: NETAPP Fibre Channel Disk (naa.60a98000572d54724a34655733506751)
    Has Settable Display Name: true
    Size: 1048593
    Device Type: Direct-Access
    Multipath Plugin: NMP
    Devfs Path: /vmfs/devices/disks/naa.60a98000572d54724a34655733506751
    Vendor: NETAPP
    Model: LUN
    Revision: 7330
    SCSI Level: 4
    Is Pseudo: false
    Status: off
    Is RDM Capable: true
    Is Local: false
    Is Removable: false
    Is SSD: false
    Is Offline: false
    Is Perennially Reserved: false
    Thin Provisioning Status: yes
    Attached Filters:
    VAAI Status: unknown
    Other UIDs: vml.020000000060a98000572d54724a346557335067514c554e202020

    Running the partedUtil getptbl command on the device shows that the device is not found.

    For example:

    partedUtil getptbl /vmfs/devices/disks/naa.60a98000572d54724a34655733506751

    Error: Could not stat device /vmfs/devices/disks/naa.60a98000572d54724a34655733506751 - No such file or directory.
    Unable to get device /vmfs/devices/disks/naa.60a98000572d54724a34655733506751
     
  7. If the device is to be permanently decommissioned, it is now possible to unpresent the LUN from the SAN. For more information, contact your storage team, storage administrator, or storage array vendor.
  8. To rescan all devices on the ESXi host, run this command:

    esxcli storage core adapter rescan [ -A vmhba# | --all ]

    The devices are automatically removed from the Storage Adapters.

    Notes:
    • A rescan must be run on all hosts that had visibility to the removed LUN.
    • When the device is detached, it stays in an unmounted state even if the device is re-presented (that is, the detached state is persistent). To bring the device back online, the device must be attached. To do this via the command line, run this command:

      esxcli storage core device set --state=on -d NAA_ID
  9. If the device is to be permanently decommissioned from an ESXi host, (that is, the LUN has been or will be destroyed), remove the NAA entries from the host configuration by running these commands:
     
    1. To list the permanently detached devices:

      esxcli storage core device detached list

      Output will be similar to:

      Device UID State
      ---------------------------- -----
      naa.50060160c46036df50060160c46036df off
      naa.6006016094602800c8e3e1c5d3c8e011 off
       
    2. To permanently remove the device configuration information from the system:

      esxcli storage core device detached remove -d NAA_ID

      For example:

      esxcli storage core device detached remove -d naa.50060160c46036df50060160c46036df

    The reference to the device configuration is permanently removed from the ESXi host's configuration.

    Note: If the device is detached but still presented (step 7 was skipped), the preceding command fails to permanently remove the device from the system, and the device is automatically re-attached. Step 7 must be completed for the device to be permanently removed.

Notes:

  • After detaching the LUN, it can be as not presented from the storage. However, if the esxcli storage core device detached remove -d NAA_ID command is run to permanently decommission the LUN from the ESXI host before removing the LUN from the storage, the LUN gets reattached to the host and must be detached again.
  • While following these steps, vCenter storage connectivity alarms will still be seen. It would be advantageous to disable the alarm when carrying out these tasks.



Additional Information

VMware Skyline Health Diagnostics for vSphere - FAQ (broadcom.com)

 
If the LUN to be removed is flagged as perennially reserved, to prevent it causing host boot delays. The perennially reserved flag can prevent a successful unmount of the LUN.
 
To remove the perennially reserved flag, run this command to remove the flag:
 
esxcli storage core device setconfig -d $device --perennially-reserved=false
 
Then run this command to retry removal of the device:
 
esxcli storage core device detached remove -d $device
 
Note: There is no negative impact in setting the flag to false, even when it is not needed.

For more information about the perennially reserved flag, see ESXi host takes a long time to start during rescan of RDM LUNs (broadcom.com)
 

简体中文：如何从ESXi 主机卸载 LUN 或分离数据存储设备 (broadcom.com)

Identifying disks when working with VMware ESXi (broadcom.com)
ESXi host takes a long time to start during rescan of RDM LUNs (broadcom.com) 
Removing an inaccesible NFS datastore with SIOC enabled fails (broadcom.com)
Como desmontar um LUN ou desanexar um dispositivo repositório de dados de hosts ESXi (broadcom.com)i
Cómo desmontar un LUN o desasociar un dispositivo de almacén de datos de los hosts ESXi (broadcom.com)
Unmounten einer LUN oder Trennen eines Datenspeichers/Speichergeräts von mehreren VMware ESXi 5.x/6.0-Hosts (broadcom.com)

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