As UNIX system administrators – we need our Operating Systems running in optimal state every time. The same is what we want to our storage systems. In EMC Powerpath there are a couple of failover policies that we can enforce to our storage devices but we must always use the one that is best suitable. We have here a LUN that is currently under Basic Failover policy even though the storage is CLARiiON:
root@solaris# powermt display dev=emcpower1a Pseudo name=emcpower1a CLARiiON ID=APM00012345678 [solaris/polaris] Logical device ID=60060160EABCDEFGHIJKL00MNOPQRS12 [LUN 155] state=alive; policy=BasicFailover; priority=0; queued-IOs=0 Owner: default=SP B, current=SP B ============================================================================== ---------------- Host --------------- - Stor - -- I/O Path - -- Stats --- ### HW Path I/O Paths Interf. Mode State Q-IOs Errors ============================================================================== 2304 pci@1c/fibre-channel@1 c3t0d1s0 SP A3 active alive 0 1 2304 pci@1c/fibre-channel@1 c3t1d1s0 SP B3 active alive 0 0 2305 pci@1d/fibre-channel@2 c4t0d1s0 SP B1 active alive 0 0 2305 pci@1d/fibre-channel@2 c4t1d1s0 SP A1 active alive 0 1
To fix this issue – we need to set the failover policy back to CLARiiON:
root@solaris# powermt set policy=co dev=emcpower1a root@solaris# powermt display dev=emcpower1a Pseudo name=emcpower1a CLARiiON ID=APM00012345678 [solaris/polaris] Logical device ID=60060160EABCDEFGHIJKL00MNOPQRS12 [LUN 155] state=alive; policy=CLAROpt; priority=0; queued-IOs=0 Owner: default=SP B, current=SP B ============================================================================== ---------------- Host --------------- - Stor - -- I/O Path - -- Stats --- ### HW Path I/O Paths Interf. Mode State Q-IOs Errors ============================================================================== 2304 pci@1c/fibre-channel@1 c3t0d1s0 SP A3 active alive 0 1 2304 pci@1c/fibre-channel@1 c3t1d1s0 SP B3 active alive 0 0 2305 pci@1d/fibre-channel@2 c4t0d1s0 SP B1 active alive 0 0 2305 pci@1d/fibre-channel@2 c4t1d1s0 SP A1 active alive 0 1
Here are the other policies that you can use to set the correct one for your storage array:
powermt set policy=rr|io|lb|so [dev=power#|all] The dev parameter is optional. If you do not include the dev parameter, the powermt set policy command changes the policy of all PowerPath devices. Parameters · so = Symmetrix Optimization (default) · co = Clariion Optimization · li = Least I/Os (queued) · lb = Least Blocks (queued) · rr = Round Robin (one path after another) · re = Request (failover only) · nr = No Redirect (no load-balancing or failover)