Managing the Switch
ExtremeWare XOS 11.3 Concepts Guide
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■Redundant or N+1—Power from a single PSU can be lost and no I/O modules are powered
down.
■Sufficient, but not redundant—Power from a single PSU is lost, and one or more I/O modules are
powered down.
■Insufficient—One or more modules are not powered up due to a shortfall of available power.
By reading the PSU information, ExtremeWare XOS determines the power status and the total amount
of power available to the system. The total power available determines which I/O modules can be
powered up.
Power Redundancy
In simple terms, power redundancy (N+1) protects the system from shutting down. With redundancy, if
the output of one PSU is lost for any reason, the system remains fully powered. In this scenario, N is the
minimum number of power supplies needed to keep the system fully powered and the system has N+1
PSUs powered.
If the system power status is not redundant, the removal of one PSU, the loss of power to one PSU, or a
degradation of input voltage results in insufficient power to keep all of the I/O modules powered up. If
there is not enough power, ExtremeWare XOS powers down the I/O modules from the highest
numbered slot to the lowest numbered slot until the switch has enough power to continue operation.
If you install or provide power to a new PSU, I/O modules powered down due to earlier insufficient
power are considered for power up from the lowest slot number to the highest slot number, based on
the I/O module’s power requirements.
Whenever the system experiences a change in power redundancy, including a change in the total
available power, degraded input voltage, or a return to redundant power, the switch sends messages to
the syslog.
Power Management Guidelines
The following list describes some key issues to remember when identifying your power needs and
installing PSUs:
â—Ź If you disable a slot, the I/O module installed in that slot is always powered down regardless of the
number of PSUs installed.
â—Ź If a switch has PSUs with a mix of both 220V AC and 110V AC inputs, ExtremeWare XOS maximizes
system power by automatically taking one of two possible actions:
â– If all PSUs are enabled then all PSUs must be budgeted at 110V AC to prevent overload of PSUs
with 110V AC inputs.
OR
â– If the PSUs with 110V AC inputs are disabled, then the PSUs with 220V AC inputs can be
budgeted with a higher output per PSU.
ExtremeWare XOS computes the total available power using both methods and automatically uses
the PSU configuration that provides the greatest amount of power to the switch. Table 13 lists
combinations where ExtremeWare XOS maximizes system power by disabling the PSUs with 110V
AC inputs.
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