When customer's MX in transitional power supply unit migration, they may notice below chassis alarms if they mix different types of PEMs,
> show chassis alarms
2 alarms currently active
Alarm time Class Description
2024-07-02 08:02:28 UTC Minor Mix of ENH-PEMs
2024-07-02 08:01:27 UTC Minor Mix of ENH-PEMs
In our example, PEM0 and PEM1 are enhanced power supply units while PEM2 and PEM3 are regular PEMs which are about to be replaced by enhanced PEMs later.
> show chassis hardware | no-more | match PEM
PEM 0 Rev 03 740-063048 <Serial Number> DC 4.1kW Power Entry Module
PEM 1 Rev 03 740-063048 <Serial Number> DC 4.1kW Power Entry Module
PEM 2 Rev 10 740-013683 <Serial Number> DC Power Entry Module
PEM 3 Rev 10 740-013683 <Serial Number> DC Power Entry Module
Moreover, they may see that the old PEMs, i.e. PEM2 and PEM3, coexisting with new PEMs show output DC power as 0.
> show chassis power detail
PEM 0:
State: Online
DC input: OK (2 feed expected, 2 feed connected)
DC input: 48.0 V input (55000 mV)
Capacity: 4100 W (maximum 4100 W)
DC output: 1540 W (zone 0, 28 A at 55 V, 37% of capacity)
PEM 1:
DC input: 48.0 V input (58000 mV)
DC output: 1798 W (zone 1, 31 A at 58 V, 43% of capacity)
PEM 2:
DC input: OK (1 feed expected, 1 feed connected)
DC input: 48.0 V input (54000 mV)
Capacity: 2800 W (maximum 2800 W)
DC output: 0 W (zone 0, 0 A at 54 V, 0% of capacity)
PEM 3:
DC input: 48.0 V input (53500 mV)
DC output: 0 W (zone 1, 0 A at 53 V, 0% of capacity)
System:
Zone 0:
Allocated power: 1630 W (2470 W remaining)
Actual usage: 1540 W
Zone 1:
Allocated power: 2165 W (1935 W remaining)
Actual usage: 1798 W
Total system capacity: 8200 W (maximum 8200 W)
Total remaining power: 4405 W
Aforementioned behaviors are considered normal and there is no action needed for customer in such transitional phase.
This is because in our case, customer has plenty of power available even all chassis power are from the only two enhanced PEMs,
The alarm will be cleared after all 4 PEMs are in the same type, i.e., enhanced PEMs and all 4 enhanced PEMs will start output power sharing.
2024-07-08 : Article Created
2026-06-11 : Mark to be external