Harvest power algorithm should ignore embedded shelves, handle shared PSUs, and include root aggregates

[cgrinds]

Thanks to Evan Lee for reporting!

Summary of the three issues:

1. In most cases, ONTAP does not report power for embedded disk shelves, and Harvest relied on that. But in some cases, ONTAP reports power for embedded disk shelves. FAS2750 is an example. Harvest should ignore embedded shelves. ONTAP Power calculation for embedded Shelf #2332 fixed in feat: ONTAP Power calculation for embedded Shelf #2333

2. Some hardware (FAS2620, FAS2750, etc.) use shared PSUs – when there are shared PSUs, Harvest double counts the PSUs power. For example: “system environment sensors show” reports node1 is using 297W and node2 is using 297W, but because the system has shared PSUs that load share power between nodes, the actual power is (297+297)/2 = 297W.

23.08 and earlier versions of Harvest would report 297W + 297W = 594W since we summed the PSU power. The fix is to detect shared PSUs and divide the total PSU power by the number of shared-nodes, resulting in 297W in this example.

3. Root aggregates should be shown in aggregate power table panel

• Finish documentation
• Include root aggregates in power calculation

[cgrinds]

The logic to determine if PSUs are shared in point two requires using system chassis fru show.

We have not been able to find a ZAPI that returns this information, which means Power would become a REST only feature.

We can gather the data via /api/private/cli/system/chassis/fru with fields=chassis-id,fru-name,name,num-nodes,status,type

[Hardikl]

Tested in main with commit 4158465

Tested in 2 AFF-250, umeng-01-02, umeng-05-06 clusters.

1. Embedded shelves are ignored to calculate the total power.
2. Total power = Nodes power + shelf power (if not embedded).
3. Root aggregates are displayed in Aggregates table.