You can adjust the perennial reservation setting on storage devices that are used as physical Raw Device Mappings (RDMs) in Windows Server Failover Clustering (WSFC) configurations.

WSFC cluster nodes that are spread over several ESXi hosts require physical RDMs. The RDMs are shared among all hosts where cluster nodes run. The host with the active node holds persistent SCSI-3 reservations on all shared RDM devices. When the active node is running and devices are locked, no other host can write to the devices. If another participating host boots while the active node is holding the lock on the devices, the boot might take unusually long time because the host unsuccessfully attempts to contact the locked devices. The same issue might also affect rescan operations.

To prevent this problem, activate perennial reservation for all devices on the ESXi hosts where secondary WSFC nodes with RDMs reside. This setting informs the ESXi host about the permanent SCSI reservation on the devices, so that the host can skip the devices during the boot or storage rescan process.

If you later re-purpose the marked devices as VMFS datastores, remove the reservation to avoid unpredictable datastore behavior.

For information about WSFC clusters, see the Setup for Windows Server Failover Clustering documentation.

Prerequisites

Before marking a device as perennially reserved, make sure the device does not contain a VMFS datastore.

Procedure

  1. In the vSphere Client, navigate to the ESXi host.
  2. Click the Configure tab.
  3. Under Storage, click Storage Devices.
  4. From the list of storage devices, select the device and click one of the following icons.
    Option Description
    Mark as Perennially Reserved Mark the selected device as perennially reserved.
    Note:

    Repeat the procedure for each RDM device that is participating in the WSFC cluster.
    Unmark as Perennially Reserved Clear perennial reservation for the device that was previously marked.

Results

The configuration is permanently stored with the ESXi host and persists across restarts.

Example

You can also use the esxcli command to mark the devices participating in the WSFC cluster.
  1. Mark the devices as perennially reserved. 
    esxcli storage core device setconfig -d naa.id --perennially-reserved=true
  2. Verify that the device is perennially reserved. 
    esxcli storage core device list -d naa.id

    In the output of the esxcli command, search for the entry Is Perennially Reserved: true.

  3. To remove the perennially reserved flag, run the following command. 
    esxcli storage core device setconfig -d naa.id --perennially-reserved=false