On 2005-05-03T13:22:32, Arthur Bergman <sky@xxxxxxxxxxx> wrote: > >How is the resultant path grouping any different than if you used the > >failover > >path grouping policy instead? > > > >-- > > > >dm-devel@xxxxxxxxxx > >https://www.redhat.com/mailman/listinfo/dm-devel > > > > Huh, as far as I understand it group_by_nodename uses the > > /sys/class/fc_transport/target0:0:0/node_name information > > from our setup, there are 8 paths to two controllers, there is no > failover cost but it defeats read caching pretty beadly to use both > controllers.. > > /sys/class/fc_transport/target0:0:0/node_name:0x50050768010003d5 > /sys/class/fc_transport/target0:0:1/node_name:0x5005076801000361 > /sys/class/fc_transport/target0:0:2/node_name:0x50050768010003d5 > /sys/class/fc_transport/target0:0:3/node_name:0x5005076801000361 > /sys/class/fc_transport/target1:0:0/node_name:0x5005076801000361 > /sys/class/fc_transport/target1:0:1/node_name:0x5005076801000361 > /sys/class/fc_transport/target1:0:2/node_name:0x50050768010003d5 > /sys/class/fc_transport/target1:0:3/node_name:0x50050768010003d5 > > > So all path that ends at a matching node_name, even if they are on > different transport targets get one path. Now figure in that this might need to be stacked with more hw-specific stuff like dm-emc ;-) I think that ought to work already if multipath-tools would set up the right cascaded multipath tables in theory though; however it might not because depending on how the stacking works some things might not propagate up or down correctly right now. Sincerely, Lars Marowsky-Brée <lmb@xxxxxxx> -- High Availability & Clustering SUSE Labs, Research and Development SUSE LINUX Products GmbH - A Novell Business -- Charles Darwin "Ignorance more frequently begets confidence than does knowledge"
