maxgroupid − replicated volume number allocation mechanism
The system control machine (SCM) has a file, /vice/vol/maxgroupid, which contains the maximum replicated (aka group) volume number that has ever been allocated in the system. This is used as a simple way to guarantee that group volume numbers are unique.
Replicated (or group) volume ids are allocated out of the same namespace as replica ids and non-replicated volumes ids. The latter two types of ids have a 1 byte (8 bit) prefix to identify the server on which they are stored. We suggest using prefixes in the range 00-7F for replicated volume ids, and prefixes in the range 80-FF for other volumes. When initializing a system, put the number you wish to use for the first replicated volume in /vice/vol/maxgroupid. For example, if you wish to use 7f000000 as the first replicated volume, create /vice/vol/maxgroupid with the number 2130706432.
/vice/vol/maxgroupid on the SCM
This file should be salvaged, but it is not.
Removing this file (without reinitializing the whole system) is a recipe for disaster. Grave confusion will result if group (or any other) volumes are created with the same number.
servers (5), createvol_rep (8)
Jay Kistler, 1990, Created