We have been running Fixed paths on our ESX hosts to connect to our MSA1500 SAN. The MSA is flashed with the v7 Active/Active firmware.
On a recent support call to VMware the techs told me that the HP MSA's do not run TRUE Active/Active and I should change the paths to MRU. It appears the SAN Compatibility guide (p34) confirms this for the v6 MSA1500 Active/Active.
If I do this wont I lose the ability to split the traffic between the two HBA's of the MSA ? So can I still use the HP ACU to choose preferred paths for each LUN or do I set to Automatic preferred paths ?
My question is how does this setting change our environment ?
ESX VI3 DL585 x4 16GB 4CPU2.8GHz
Silkworm200E x2 Dual Fabric SAN
MSA1500cs x2 Active/Active
It is better to set it to MRU as it is not a true A/A. Otherwise u might run into consistency issues. Refer to the SAN config guide located in docs.
If the disk IO cannot be split between controllers then I will flash the MSA's back to Active/Passive. Can we use MRU paths and still have Manual Preferred Path Mode configured in the ACU Redundancy Settings?
At this time esx support only one active path to a LUN. From this point of view there is no difference in performance between MRU and Fixed. When you choose Fixed way to a LUN it menans that if this way is ok esx server use always this way. MRU means that there is no prefferred way and first alive way will be used.