On Tue, 02 Aug 2005 09:37:14 -0500 "Christopher C. Weis" <ccweis@xxxxxxxxx> wrote > I have a multipath SAN environment with storage controllers that are > active/active. However, the controllers are not active/active at the > LUN-level without a performance penalty, meaning if two > servers want to > see the same LUN (as in a clustered filesystem environment), they both > need to be using the same controller. I'm trying to figure > out a way to > statically "order" the paths so that I can copy a config to all of the > nodes using the CFS. > > >From what I've read, in a single-server environment with controllers > such as the ones I'm dealing with, the path_grouping_policy should be > set to "group_by_serial", which should work fine, but in a clustered > environment, I need to be sure that the path ordering is the same. > > Are there any path_selectors, other than round-robin, that might > accomplish this? Any other ideas? > One was is to configure each multipath to have two groups with one group having a higher priority than the other based on whether the path accesses the fast path controller. The assignment of the highest priority path group is non deterministic when using the "group_by_serial" path grouping policy. 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.
