Cannot remove a LUN extent

Products

• VMware vSphere ESXi

Issue/Introduction

This article explains why it is not possible to remove an extent from a datastore, and discusses the available options.

Resolution

It is not possible to remove an extent from an existing datastore. Once an extent is added, it is not possible to remove it without compromising the data residing on the extent. (See A device backing some part of the VMFS volume is offline (2008164).)
 

The only options available are:

• Reclaim the space used. To reclaim the space:
   
  1. Evacuate all virtual machines from that datastore (via storage vMotion or cold migration) to other datastores within your environment.
     
     Note: If you do not have vCenter Server within your environment, see Moving or copying a virtual machine within a VMware environment (1000936).
      
  2. Destroy the extended datastore.
  3. Re-create the datastore with the desired dimensions.
  4. Move the virtual machines back.
     
      
• Migrate the virtual machines to a new datastore which does not use the extent. To migrate:
  1. Provision a new LUN with enough storage capacity to house the virtual disks you wish to run on that datastore. For more information, see your vendor documentation.
  2. Create a new datastore on the newly created LUN. For more information, see the Configuration Guide for your version of VMware ESX or ESXi.
  3. Use the cold migration or storage vMotion features from vCenter Server to relocate the virtual machines to the datastore created in step 2.
     
     Note: If you do not have vCenter Server within your environment, see Moving or copying a virtual machine within a VMware environment (1000936).
      
  4. Ensure that all virtual machines which have been migrated are functioning properly in their new datastore.
  5. Remove the original datastore and LUN which used the extent. For more information, see the Configuration Guide for your version of VMware ESX or ESXi.