Service Manual

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Influencing Management Unit Selection on a Stack
Stack priority is the system variable that Dell Networking OS uses to determine which units in the stack
are the master and standby management units. If multiple units tie for highest priority, the unit with the
highest MAC address prevails.
If management was determined by priority only, a change in management occurs when:
• the management unit is powered down or a failover occurs.
• you disconnect the management unit from the stack.
When the management unit fails, the unit disappears from the stack topology. At that time, the standby
unit detects the communication loss and switches from the standby unit role to the management unit
role in the stack. From the remaining units in the stack, the system selects a new standby unit based on
the unit priority using the same algorithm used when the stack was initially created. When the failed unit
recovers, it takes the next available role, usually that of a stack member.
• Influence the selection of the stack management units.
CONFIGURATION mode
stack-unit priority
The unit with the numerically highest priority is elected the master management unit, and the unit
with the second highest priority is the standby unit.
The range is from 1 to 14.
The default is 0.
Managing Redundancy on a Stack
Use the following commands to manage the redundancy on a stack.
• Reset the current management unit and make the standby unit the new master unit.
EXEC Privilege mode
redundancy force-failover stack-unit
A new standby is elected. When the former stack master comes back online, it becomes a member
unit.
• Prevent the stack master from rebooting after a failover.
CONFIGURATION mode
redundancy disable-auto-reboot stack-unit
This command does not affect a forced failover, manual reset, or a stack-link disconnect.
• Display redundancy information.
EXEC Privilege mode
show redundancy
Stacking
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