> > > > Seems like you want to use the "group_by_priority" path > grouping policy and > > create and get_priority executable which when invoked will > return a 1 for > > fast path and 0 for slow path. See the code for > mpath_prio_emc, the > > get_priority executable for the EMC CLARiiON array in > > multipath-tools/path_priority/pp_emc/pp_emc.c. > > > Yes, also note "group_by_priority" path grouping policy may be > overkill > for the context. PG produced by "group_by_serial" can be > sorted with an > adequate prioritizer too. > > Does this mean that "group_by_serial" utilizes a > "default_prio_callout" program/script as well, or is there another > callout (or something totally different that I'm missing)? > Path prio are fetched in the path discovery phase (via callout, or defaulting to 1 if no callout specified). PG policies just decide the path grouping. There is a implicit notion of PG prio, which is sum(path pio). group_by_prio is special here : it's a mean for admins to implement a new pgpolicy without having to hack the tools ... just with shell script as prio callouts. Regards, -- christophe varoqui <christophe.varoqui@xxxxxxx>
