Multipath path groups

Question

For native RHEL multipathing, what is the difference between having 2 paths in a single path group as opposed to 2 path groups (with same priority) containing 1 path each?

Is one preferable to the other?

Two paths in single path group

# multipath -ll
mpath2 (360060e8005b0e5000000b0e5000001df) dm-11 HP,OPEN-V
[size=5.0G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
\_ 4:0:0:2  sdc 8:32  [active][ready]
\_ 6:0:0:2  sdn 8:208 [active][ready]

Two paths groups with one path each

# multipath -ll
mpath2 (360060e8005b0e5000000b0e5000001df) dm-11 HP,OPEN-V
[size=5.0G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=1][active]
\_ 4:0:0:2  sdc 8:32  [active][ready]
\_ round-robin 0 [prio=1][enabled]
\_ 6:0:0:2  sdn 8:208 [active][ready]

Answer 1

When you have only one path group your multipath configuration is active/activce the io requests are spread in two path, in your second case, you use only on path and your multipath configuration is active/passive, so you have active/failover, you only use the second path if the first group fail, multipath failover is between groups(NO PATH)