Description

This article describes a cosmetic bug in Junos: A switched-off power supply module (PSM) is showing an old DC output value. This causes the Actual Usage value resulting from a show chassis power command to be inaccurate.

Symptoms

An example explaining away the issue is given below.

Initial status

root@router> show chassis power | no-more

- omitted -

PSM 9:
State: Online
DC input: OK (INP0 feed expected, INP0 feed connected)
Capacity: 2100 W (maximum 2500 W)
DC output: 284.62 W (Upper Zone, 5.50 A at 51.75 V, 13.55% of capacity)

PSM 10:
State: Online
DC input: OK (INP0 feed expected, INP0 feed connected)
Capacity: 2100 W (maximum 2500 W)
DC output: 284.62 W (Upper Zone, 5.50 A at 51.75 V, 13.55% of capacity)

PSM 11:
State: Online
DC input: OK (INP0 feed expected, INP0 feed connected)
Capacity: 2100 W (maximum 2500 W)
DC output: 283.26 W (Upper Zone, 5.50 A at 51.50 V, 13.49% of capacity)

- omitted -

System:
Upper Zone:
Capacity: 6300 W (maximum 7500 W)
Allocated power: 5662 W (638 W remaining)
Actual usage: 852.50 W
Lower Zone:
Capacity: 12600 W (maximum 15000 W)
Allocated power: 6252 W (6348 W remaining)
Actual usage: 1344.44 W
Total system capacity: 18900 W (maximum 22500 W)
Total remaining power: 6986 W

Notes

Actual Usage is the amount of power a router is using now. It depends on how much traffic and resources are used in the router.

Actual usage in Upper Zone (852.50 W) is calculated as follows: 284.62 W + 284.62 W + 283.26.

Turn off PSM 9

root@router> show chassis power | no-more

- omitted -

PSM 9:
State: Present
DC input: Check (INP0 feed expected, INP0 feed connected)
Capacity: 2100 W (maximum 2500 W)
DC output: 297.56 W (Upper Zone, 5.75 A at 51.75 V, 14.17% of capacity)

PSM 10:
State: Online
DC input: OK (INP0 feed expected, INP0 feed connected)
Capacity: 2100 W (maximum 2500 W)
DC output: 401.06 W (Upper Zone, 7.75 A at 51.75 V, 19.10% of capacity)

PSM 11:
State: Online
DC input: OK (INP0 feed expected, INP0 feed connected)
Capacity: 2100 W (maximum 2500 W)
DC output: 399.12 W (Upper Zone, 7.75 A at 51.50 V, 19.01% of capacity)


- omitted -

System:
Upper Zone:
Capacity: 4200 W (maximum 5000 W)
Allocated power: 5662 W (0 W remaining)
Actual usage: 1097.75 W
Lower Zone:
Capacity: 12600 W (maximum 15000 W)
Allocated power: 6252 W (6348 W remaining)
Actual usage: 1447.88 W
Total system capacity: 16800 W (maximum 20000 W)
Total remaining power: 6348 W

Notes

Increased actual usage in Upper Zone (1097.75 W) results in a cosmetic bug: PSM 9 shows 297.56 W, even though it was turned off by the switch.

This issue does not occur if the PSM is removed or if no feed is connected, as follows:

PSM 9:
State: Present
DC input: Check (Both feed expected, No feed connected)
Capacity: 2100 W (maximum 2500 W)
DC output: 0.00 W (Lower Zone, 0.00 A at 0.00 V, 0.00% of capacity)

Solution

 

This issue is fixed in Junos 12.3R7, 13.1R4, and 13.2R2.