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PDL AutoRemove feature in vSphere 5.5 and vSphere 6.x (2059622)

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Purpose

This article provides information on the Permanent Device Loss (PDL) AutoRemove feature in vSphere 5.5 and vSphere 6.x

Resolution

PDL is a situation that can occur when a disk device either fails or is removed from the vSphere host in an uncontrolled fashion. PDL detects if a disk device has been permanently removed, that is, the device will not return based on SCSI sense codes. When the device enters this PDL state, the vSphere host can take action to prevent directing any further, unnecessary I/O to this device. This alleviates other conditions that might arise on the host as a result of this unnecessary I/O. With vSphere 5.5, a new feature called PDL AutoRemove is introduced. This feature automatically removes a device from a host when it enters a PDL state. Because vSphere ESXi hosts have a limit of 255 disk devices per host, a device that is in a PDL state can no longer accept I/O, but can still occupy one of the available disk device spaces. Therefore, it is better to remove the device from the host.

PDL AutoRemove occurs only if there are no open handles left on the device. The auto-remove takes place when the last handle on the device closes. If the device recovers, or if it is re-added after having been inadvertently removed, it is treated as a new device.

The AutoRemove feature is enabled by default in vSphere 5.5 and vSphere 6.x.
 

Disabling the PDL AutoRemove feature in vSphere 6.x

In vSphere 6.x, the response to a PDL is different. Due to this change, VMware recommend you do not disable the AutoRemoveOnPDL feature in vSphere 6.x.

In vSphere 6.x, the expectation is that a device in a PDL state will not return. Therefore, the device needs to be removed from the ESXi host, before it can be recovered. If the AutoRemoveOnPDL feature is disabled, a manual rescan is required to remove the device while in a PDL state.
 
Note: For vSphere Metro Storage Cluster (vMSC) environments, VMware recommends to have AutoremoveOnPDL set to 1 explicitly for vSphere 6.x.

If you wish to proceed with disabling the AutoRemoveOnPDL feature in ESXi 6.x, apply these steps:
  1. Connect to the ESXi 6.x host using the console or SSH. For more information, see Using ESXi Shell in ESXi 5.x and 6.x (2004746).

  2. Run this command to disable AutoRemove:

    esxcli system settings advanced set -o "/Disk/AutoremoveOnPDL" -i 0

Disabling the PDL AutoRemove feature in vSphere 5.5

To disable the AutoRemoveOnPDL feature in ESXi 5.5, apply these steps:

  1. Connect to the ESXi 5.5 host using the console or SSH. For more information, see Using ESXi Shell in ESXi 5.x and 6.x (2004746).

  2. Run this command to disable AutoRemove:

    esxcli system settings advanced set -o "/Disk/AutoremoveOnPDL" -i 0

Notes:
  • There is no guarantee of data integrity can be given if a device returns from PDL.
  • To re-enable the AutoRemove feature, run this command from a shell session to the ESXi host:

    esxcli system settings advanced set -o "/Disk/AutoremoveOnPDL" -i 1

Additional Information

See Also

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