A ServeRAID merge group number is used to uniquely identify a particular partition to a ServeRAID controller. It is different from a ServeRAIDVolumeId[1] in that the volume ID is not constant, but the merge group number is. The merge group numbers of shared volumes are in the range of 1 to 8 inclusive.
Volume IDs of shared partitions are assigned in the order they are failed over to the system. As a result, their value depends on the order in which the parititions are made available to Linux by the ServeRAID resource agent.[2].
| [1] | http://www.linux-ha.org/ServeRAIDVolumeId |
| [2] | http://www.linux-ha.org/HeartbeatResourceAgent/ServeRAID |
| [3] | http://www.linux-ha.org/ServeRAIDLogicalVolume |
This information provided courtesy of the Linux-HA project at http://linux-ha.org/