Storage vMotion vs SAN Replication

Duncan Epping at Yellow Bricks yesterday posted a brief but very interesting article about the best approach to pursue when a company is about to replace its SAN arrays: Storage vMotion or SAN Replication.

Epping breaks down the pros and cons of both approaches:

SAN Replication

  • Can utilize Array based copy mechanisms for fast replication (+)
  • Per LUN migration, high level of concurrency (+)
  • Old volumes still available (+)
  • Need to resignature or mount the volume again (-)
    • A resignature also means you will need to reregister the VM! (-)
  • Downtime for the VM during the cut over (-)

Storage vMotion

  • No downtime for your VMs (+)
  • Fast Storage vMotion when your Array supports vStorage APIs for Array Integration (VAAI) (+)
    • If your Array doesn’t support VAAI migrations can be slow (-)
    • Induced cost if VAAI isn’t supported (-)
    • Only intra Array not across arrays (-)
  • No resignaturing or re-registering needed (+)
  • Per VM migration (-)
    • Limited concurrency (2 per host, 8 per VMFS volume) (-)