We have several VMware ESXi hosts accessing multiple datastore stored on a fiber channel SAN.

We have found that some of the hosts are still set to "Most recently used" mode for their multipathing policy.

I would like to change these remaining hosts to use "Round Robin", as I understand that woud be the best option in our scenario, but I would like to know if changing this policy while in a live environment, has any effect on connectivity to the datastores?


Generally not no but it would be useful to know exactly what make and model your array is as not all support the active/active ALUA model that RR best serves.

  • Thanks for this. The hosts use QLogic 8Gb QLE2560 HBAs, connecting via SANBox 5800v switches, to a dual controller HP P2000 G8 fiber channel SAN. I think everything will support it, as a couple of our hosts are already set to this. – James Edmonds Jun 2 '17 at 11:50
  • Ah I know P2000's (presumably you mean a G3) - they're active/active so you can definitely use RR and move to RR with only a momentary (subsecond) latency blip if any. :) – Chopper3 Jun 2 '17 at 12:51
  • Yep, meant G3, not G8 ;) – James Edmonds Jun 2 '17 at 14:23

No, there's usually no impact.

This setting can be changed on the fly, assuming the correct "plumbing" is in place.

  • Thank you for your answer. Yes I think all plumbed in correctly, as two hosts are already using this particular policy. I will go ahead and pull the trigger. – James Edmonds Jun 2 '17 at 11:51
  • Note I will accept Choppers answer, only because it was a couple of minutes before yours, and he had the suggestion of also providing my HBA/Array details. If I could mark both as correct I would. – James Edmonds Jun 2 '17 at 11:53
  • @JamesEdmonds Whatever. – ewwhite Jun 2 '17 at 12:19

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