Allied Telesis AlliedWare Plus Operating System Version 5.4.4C (x310-26FT,x310-26FP,x310-50FT,x310-50FP) - Manual (Page 2129)

VCStack Introduction
Software Reference for x310 Series Switches
C613-50046-01 REV A AlliedWare Plus TM Operating System - Version 5.4.4C 82.15
Combining separate stacks
Two small (2 member) stacks can be combined into a single 4 member stack simply by
physically reconnecting the stack members and rebooting. Note that the likelihood of a
successful stack recombination is greatly increased if you set the stack IDs of each stack
member to be unique within the combined stack that you are creating.
For example, consider two individual 2 member stacks that are to be combined into one 4
member stack, where the members of each stack had the stack member IDs of 1 and 2.
Then, before you combine the stacks, you should renumber the member IDs of stack two
to be 3 and 4.
Disabled Master
A properly functioning VCStack contains an (active) master and one or more (backup)
members. Under fault conditions it is possible for some of the stack members to loose
connectivity with the stack master. In this situation the stack members without master
connectivity will form themselves into a stack stub and elect a “Disabled Master” to
manage the stub until the fault is rectified. Once elected to this state the disabled master
will disable all of its own ports and those of all other stack members within the stub. Apart
from this, the operation and ‘look and feel’ of a disabled master is very similar to an active
master.
By disabling all the stub’s switchports, the disabled master avoids potential network
connectivity problems that could result from by having two stack masters using the same
configuration, or two switches in separated stubs trying to share the same “logical”
communications paths such as a non functioning aggregated links. The active master’s
ports are unaffected by this, and they will continue to forward traffic normally.
Note that status information for members of the stack stub can be accessed by logging
into the disabled master, in the same way as obtaining status information for a normal
stack.
Note In a stack of more than two units, several stack members could become
separated from the stack master. In this case, these stack members will form a
stack stub together. Only one stack member will become the disabled master.
The other switches will remain as backup stack members, but their switchports
will still be disabled. Status information for the stack members can be accessed
by logging into the disabled master, in the same way as obtaining status
information for a normal stack.