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The total capacity of this concatenated metadevice is the combined 
capacities of the three drives. If each drive is 4 gigabytes, for example, 
the metadevice has an overall capacity of 12 gigabytes.

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The 

Solstice DiskSuite software tracks which disk partitions belong to 

which metadevices with a state database. A state database stores 
information on disk about the state of your 

Solstice DiskSuite 

configuration. 

The state database consists of multiple copies of the basic database. The 
copies, referred to as state database replicas, ensure that the data in 
the database is always valid. Having multiple copies protects against 
data loss from single points-of-failure. The state database tracks the 
location and status of all state database replicas. 

Solstice DiskSuite 

cannot operate until you have created the state database and its replicas: 
the software must have an operating state database. 

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A mirror is a metadevice that can copy data from one metadevice to 
another. The metadevices containing the data are called submirrors. 
The process of copying the data between submirrors is called mirroring.

Mirroring provides redundant copies of data. To a software application, a 
mirror looks just like a physical disk. The mirror accepts I/O requests and 
converts them into I/O requests for the submirrors. The submirrors in 
turn—being metadevices themselves—convert I/O requests from the 
mirror into I/O requests for the underlying physical disks.

A mirror can be two-way or three-way. A two-way mirror is a mirror with 
two submirrors; a three-way mirror has three submirrors. CMS supports 
only two-way mirrors. The illustration below shows a typical two-way 
mirror, d21, consisting of the submirrors d19 and d20.