For information about the purpose and function of device groups, see Device Groups in Oracle Solaris Cluster Concepts Guide .
Consider the following points when you plan device groups:
Failover – You can configure multihost disks and properly configured volume-manager devices as failover devices. Proper configuration of a volume-manager device includes multihost disks and correct setup of the volume manager itself. This configuration ensures that multiple nodes can host the exported device. You cannot configure tape drives, CD-ROMs or DVD-ROMs, or single-ported devices as failover devices.
Mirroring – You must mirror the disks to protect the data from disk failure. See Mirroring Guidelines for additional guidelines. See Configuring Solaris Volume Manager Software and your volume-manager documentation for instructions about mirroring.
Storage-based replication – Disks in a device group must be either all replicated or none replicated. A device group cannot use a mix of replicated and nonreplicated disks.