Mirroring all multihost disks in a Sun Cluster configuration enables the configuration to tolerate single-disk failures. Sun Cluster software requires that you mirror all multihost disks across disk expansion units.
Consider the following points when mirroring multihost disks.
Separate disk expansion units - Each submirror of a given mirror or plex should reside in a different multihost disk expansion unit.
Disk space - Mirroring doubles the amount of necessary disk space.
Three-way mirroring - Solstice DiskSuite software and VERITAS Volume Manager (VxVM) support three-way mirroring. However, Sun Cluster requires only two-way mirroring.
Number of metadevices - Under Solstice DiskSuite software, mirrors consist of other metadevices such as concatenations or stripes. Large configurations might contain a large number of metadevices. For example, seven metadevices are created for each logging UFS file system.
Differing disk sizes - If you mirror to a disk of a different size, your mirror capacity is limited to the size of the smallest submirror or plex.
For more information about multihost disks, see Sun Cluster 3.0 U1 Concepts.