Best practices for VMware ESX or ESXi when scheduling SAN downtime

Products

• VMware vSphere ESXi

Issue/Introduction

This article provides best practice procedures for VMware ESX or ESXi when scheduling downtime for connected SAN storage.

Environment

VMware ESX Server 3.0.x
VMware ESXi 4.1.x Installable
VMware ESX Server 2.5.x
VMware vSphere ESXi 5.5
VMware ESXi 3.5.x Embedded
VMware ESX 4.1.x
VMware ESXi 3.5.x Installable
VMware ESXi 4.0.x Embedded
VMware vSphere ESXi 5.1
VMware vSphere ESXi 6.0
VMware ESXi 4.0.x Installable
VMware ESXi 4.1.x Embedded
VMware ESX Server 3.5.x
VMware ESX Server 2.1.x
VMware ESX 4.0.x
VMware vSphere ESXi 6.5
VMware ESX Server 2.0.x
VMware vSphere ESXi 5.0

Resolution

When physically moving an array with running virtual machines, follow this best practice procedure:

1. Shut down all virtual machines utilizing the targeted SAN storage, or migrate the virtual machines to standby/alternate storage.
2. Un-present the targeted LUNs from the ESX/ESXi hosts, according to the applicable steps below:

   VMware ESX 3.x

   1. Unmask the LUNs from your ESX hosts (remove visibility or access). For additional steps and information, refer to your SAN vendor documentation.
   2. Select an ESX Server in your host inventory, its Configuration tab, then Storage Adapters.
   3. Rescan the ESX Server's Host Bus Adapters (HBAs).
   4. Verify that the LUNs are no longer appear in the lower pane when selecting each of your HBAs.
    

   VMware ESX/ESXi 4.x

   For instructions on how to safely un-present LUNs from an ESX/ESXi 4.x host, see Removing a LUN containing a datastore from VMware ESXi/ESX 4.x (1029786).
   
   After completing these steps, verify that the array's LUNs are no longer visible to the ESX/ESXi 4.x hosts, and no dead paths persist.
    

   VMware ESXi 5.x

   For instructions on how to safely un-present LUNs from an ESXi 5.x host, see:
   
   Note: This process also applies for ESXi 6.0 and ESXi 6.5
   
   Unmounting a LUN or detaching a datastore/storage device from multiple ESXi 5.x hosts (2004605)
   Best Practice: How to correctly remove a LUN from an ESX host

   Note: Virtual machines display as Inaccessible if their datastores are not accessible or mounted. Through the detailed procedure in this article, this behavior is expected. They will return to a normal state after the original storage devices are re-presented to the VMware ESX/ESXi hosts.
    
3. Complete your scheduled downtime on the SAN. Proceed to the remaining steps only after the SAN components are confirmed available or online.
4. Re-present the LUNs to the ESX/ESXi hosts, in accordance to your SAN's documentation and best-practices.
5. Rescan the HBA of the ESX/ESXi hosts.
6. Confirm that the virtual machines return to a normal state, as opposed to Inaccessible.
7. Power on the virtual machines.

Alternate method

1. Shut down the virtual machines.
2. Shut down the ESX/ESXi hosts for the duration of the downtime.
3. Start the ESX/ESXi hosts and confirm that the LUNs are discovered and accessible.
4. Start the virtual machines.