Saturday, October 4, 2014

How Storage vMotion works ?

How Storage vMotion works?

Storage vMotion enables live migration of running virtual machine disk files from one storage location to another with no downtime or service disruption.

  • This simplifies storage array migration or storage upgrades.
  • Dynamically optimize storage I/O performance.
  • Efficiently utilize storage and manage capacity.
  • Manually balances the storage load.

Storage vMotion process:

  1. vSphere copies the non-volatile files that make up a VM: vmx, swp, logs & snapshots.
  2. vSphere starts a ghost or shadow VM on the destination datastore. Because the ghost VM does not yet have a virtual disk (that hasn't been copied over yet), it sits idle waiting for its virtual disks.
  3. Storage vMotion first creates a destination disk. Then a mirror device - a new driver that mirrors I/Os between source & destination.
  4. I/O mirroring in place, vSphere makes a single-pass copy of virtual disks from source to destination. As the changes are made to the source, the mirror driver ensures that changes are also reflected at the destination.
  5. When the virtual disk copy completes, vSphere quickly suspends & resumes in order to transfer control over to the ghost VM on the destination datastore.
  6. Files on the source datastore are deleted.

Virtual mode RDM storage vMotion - if you want to migrate only the vmdk mapping file - select “Same Format as source”.

Physical mode RDMs are not affected.

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