Dell PowerConnect 8024 User Configuration Manual page 128

NOTE:
The terms "Master" and "Manager/Management Unit" are often used
interchangeably through out this chapter.
In most cases, a switch that is added to an existing stack will become a stack
member, and not the Management Unit. When you add a switch to the stack,
one of the following scenarios takes place regarding the management status of
the new switch:
• If the switch has the Management Unit function enabled but another
Master unit is already active, then the switch changes its configured
Management Unit value to disabled.
• If the Management Unit function is unassigned and there is another
Management Unit in the system then the switch changes its configured
Management Unit value to disabled.
• If the Management Unit function is enabled or unassigned and there is no
other Management Unit in the system, then the switch becomes
Management Unit.
• If the Management Unit function is disabled, the unit remains a non-
Management Unit.
If the entire stack is powered OFF and ON again, the unit that was the
Management Unit before the reboot will remain the Management Unit after
the stack resumes operation.
You can manually set the unit number for the switch. To avoid unit-number
conflicts, one of the following scenarios takes place when you add a new
member to the stack:
• If the switch has a unit number that is already in use, then the unit that
you add to the stack changes its configured unit number to the lowest
unassigned unit number.
• If the switch you add does not have an assigned unit number, then the
switch sets its configured unit number to the lowest unassigned unit
number.
• If the unit number is configured and there are no other devices using the
unit number, then the switch starts using the configured unit number.
• If the switch detects that the maximum number of units already exist in
the stack making it unable to assign a unit number, then the switch sets its
unit number to
128
Managing a Switch Stack
unassigned and does not participate in the stack.