If you use Solaris Volume Manager as your volume manager for shared device groups, carefully plan the distribution of your replicas. In two-room configurations, all disksets should be configured with an additional replica in the room that houses the cluster quorum device.
For example, in three-room two-node configurations, a single room houses both the quorum device and at least one extra disk that is configured in each of the disksets. Each diskset should have extra replicas in the third room.
Refer to your Solaris Volume Manager documentation for details about configuring diskset replicas.