On mar, 2005-08-02 at 15:07 -0400, goggin, edward wrote: > 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. > 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. Regards, -- christophe varoqui <christophe.varoqui@xxxxxxx>
