Raid
The raid block houses three hard drives which will be combined into a single file system. This combined file system has the size of the sum of the capacities of the individual hard drives and is available to all computers connected to the raid.
The raid only works (and shows up as a file system) when three hard drives are present. The hard drives may differ in size.
Beware that adding a hard drive to the raid block will wipe it of its contents. Removing a single hard drives from a complete raid will wipe the entire raid. Adding the disk back in will not restore the old files; the raid will be re-initialized as an empty file system.
Breaking a raid block will retain its contents, so it can be safely relocated without losing any data.