vSphere Storage vMotion explained

vSphere Storage vMotion is a vSphere migration mechanism that moves a powered-on virtual machine’s files to a new datastore with no disruption. Storage vMotion migrates a running VM’s virtual disks from one datastore to another datastore, but leaves the VM executing on the same ESXi host. It is usually used for the following purposes:

  • storage maintenance – you can move your virtual machines from a storage device to allow maintenance or reconfiguration of the storage device without downtime.
  • storage load redistribution – you can redistribute virtual machines or virtual disks to different storage volumes to balance capacity and improve performance.
  • datastore upgrade – you can use Storage vMotion to migrate virtual machines when you upgrade datastores from VMFS2 to VMFS5.

Migration with Storage vMotion renames virtual machine files on the destination datastore to match the inventory name of the virtual machine. The migration renames all virtual disk, configuration, snapshot, and .nvram files. This feature can not be turned off.

During a migration, you can choose to transform virtual disks from Thick-Provisioned Lazy Zeroed or Thick-Provisioned Eager Zeroed to Thin-Provisioned or the reverse.

The following requirements must be met in order for a Storage vMotion migration to succeed:

  • virtual machine disks (.vmdk files) must be in persistent mode or be raw device mappings (RDMs).
  • you can not perform a migration during a VMware Tools installation.
  • you cannot move virtual disks greater than 2TB from a VMFS5 datastore to a VMFS3 datastore.
  • the host on which the virtual machine is running must have access to both the source and destination datastores.
  • the host on which the virtual machine is running must be licensed to use Storage vMotion.
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