MSA2012i, ESX 4.x -- MRU or round robin, which is better??

[Tom Lyczko]

We have an MSA2012i with vSphere/ESX 4.x -- presently it uses MRU, would anything be gained by changing it to round robin??

Thank you, Tom

[Steven Clementi]

Do you have dual controllers on the the MSA?


Steven

[Tom Lyczko]

Forgot to say that...yes, we do.

vSphere and the SAN are using software iSCSI, which means only one vmhba per host, which I've come to learn means that round robin wouldn't have any effect, since it requires multiple HBAs.

Thank you, Tom

[Uwe Zessin]

ESX 4 allows multiple VMkernel ports for iSCSI.

Even with one initiator port you should see two paths to a volume (even on ESX 3.5) if you have properly presented the volume to both host ports of the controller managing the vdisk on which the volume is located.

[Tom Lyczko]

Then I have indeed set up things correctly.
In vCenter I see two paths per LUN in the storage adapters' Paths view, all are marked active, and one of each path also notes I/O, which makes sense since I don't have multiple HBAs.
Thank you, Tom