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## How does the Onboard Administrator calculate power?

Tristan had a question on how the OA calculates enclosure power.

******************

Hello,

Can someone explain how the OA calculates the enclosure power capacity to be 7400W in an enclosure with 6 x 2250W and AC redundancy mode set ?

The customer also indicates that the power capacity reported by the OA is correct when the blades are in stand-by.

It shows 6750W (3 x 2750W) with the servers in stand-by.

It changes to 7400W when the blades are powered on one by one.

Showall extracts are copies below.

Thank you,

Tristan

>SHOW ENCLOSURE POWER_SUMMARY

Enclosure Bay Output Allocation:

Bay               Power Allocated (Watts DC)

-------------     --------------------------

Devices                   6520

Interconnects          +   380

Fans                   +   500

-------

=  7400

Enclosure Output Power Summary:

Enclosure             Watts DC

----------------      --------

Power Capacity            7400

Power Allocation       -  7400

Power Available        =     0

Enclosure Input Power Summary:

Enclosure              Watts AC

-----------------      --------

Present Power             3170

Max Input Power           8998

Dynamic Power Cap      Not Set

Power Limit            Not Set

Device Bay Power Summary:

%      Minimum     Power

Power Cap   Power  Power Cap   Allocated

Bay  Name                 (Watts DC)  Cap    (Watts DC)  (Watts DC)

---  -------------------  ----------  -----  ----------  ----------

1  xxxxxxxxxxxxxxxxxxx      N/A      N/A      206         395

2  xxxxxxxxxxxxxxxxxxx      N/A      N/A      210         395

3  xxxxxxxxxxxxxxxxxxx      N/A      N/A      211         410

4  xxxxxxxxxxxxxxxxxxx      N/A      N/A      208         402

5  xxxxxxxxxxxxxxxxxxx      N/A      N/A      208         401

6  xxxxxxxxxxxxxxxxxxx      N/A      N/A      209         408

7  xxxxxxxxxxxxxxxxxxx      N/A      N/A      206         387

8  xxxxxxxxxxxxxxxxxxx      N/A      N/A      209         400

9  xxxxxxxxxxxxxxxxxxx      N/A      N/A      218         424

10  xxxxxxxxxxxxxxxxxxx      N/A      N/A      213         411

11  xxxxxxxxxxxxxxxxxxx      N/A      N/A      217         422

12  xxxxxxxxxxxxxxxxxxx      N/A      N/A      219         427

13  xxxxxxxxxxxxxxxxxxx      N/A      N/A      216         408

14  xxxxxxxxxxxxxxxxxxx      N/A      N/A      213         409

15  xxxxxxxxxxxxxxxxxxx      N/A      N/A      214         414

16  xxxxxxxxxxxxxxxxxxx      N/A      N/A      212         407

----------  ---------

=  3389     =  6520

Interconnect Bay Power Summary:

Bay  Name                              Power Allocated (Watts DC)

---  --------------------------------  --------------------------

1  HP VC Flex-10/10D Module                        75

2  HP VC Flex-10/10D Module                        75

3  HP VC 8Gb 20-Port FC Module                     40

4  HP VC 8Gb 20-Port FC Module                     40

5  HP VC Flex-10/10D Module                        75

6  HP VC Flex-10/10D Module                        75

-------

=   380

Fan Power Summary:

Total Fans        Fan Rule          Present Power   Power Allocated

(Number of Fans)  (Number of Fans)  (Watts DC)      (Watts DC)

----------------  ----------------  --------------  ---------------

10                10                180             500

>SHOW ENCLOSURE POWERSUPPLY ALL

Power Supply #1 Information:

Status: OK

AC Input Status: OK

Output Capacity: 2250 Watts DC

Current Power Output: 440 Watts DC

Serial Number: 5A22B0FHLW12PX

Product Name: HP BladeSystem c-Class P/S

Part Number: 412138-B21

Spare Part Number: 411099-001

Product Ver: 01

Diagnostic Status:

Internal Data                            OK

Device Failure                           OK

Power Cord                               OK

Power Supply #2 Information:

Status: OK

AC Input Status: OK

Output Capacity: 2250 Watts DC

Current Power Output: 440 Watts DC

Serial Number: 5A22B0FHLW12PT

Product Name: HP BladeSystem c-Class P/S

Part Number: 412138-B21

Spare Part Number: 411099-001

Product Ver: 01

Diagnostic Status:

Internal Data                            OK

Device Failure                           OK

Power Cord                               OK

Power Supply #3 Information:

Status: OK

AC Input Status: OK

Output Capacity: 2250 Watts DC

Current Power Output: 440 Watts DC

Serial Number: 5A22B0FHLW12QE

Product Name: HP BladeSystem c-Class P/S

Part Number: 412138-B21

Spare Part Number: 411099-001

Product Ver: 01

Diagnostic Status:

Internal Data                            OK

Device Failure                           OK

Power Cord                               OK

Power Supply #4 Information:

Status: OK

AC Input Status: OK

Output Capacity: 2250 Watts DC

Current Power Output: 440 Watts DC

Serial Number: 5A22B0FHLVY0F9

Product Name: HP BladeSystem c-Class P/S

Part Number: 412138-B21

Spare Part Number: 411099-001

Product Ver: 01

Diagnostic Status:

Internal Data                            OK

Device Failure                           OK

Power Cord                               OK

Power Supply #5 Information:

Status: OK

AC Input Status: OK

Output Capacity: 2250 Watts DC

Current Power Output: 440 Watts DC

Serial Number: 5A22B0FHLW12QI

Product Name: HP BladeSystem c-Class P/S

Part Number: 412138-B21

Spare Part Number: 411099-001

Product Ver: 01

Diagnostic Status:

Internal Data                            OK

Device Failure                           OK

Power Cord                               OK

Power Supply #6 Information:

Status: OK

AC Input Status: OK

Output Capacity: 2250 Watts DC

Current Power Output: 440 Watts DC

Serial Number: 5A22B0FHLW12QM

Product Name: HP BladeSystem c-Class P/S

Part Number: 412138-B21

Spare Part Number: 411099-001

Product Ver: 01

Diagnostic Status:

Internal Data                            OK

Device Failure                           OK

Power Cord                               OK

Power Subsystem:

Status: OK

Power Mode: Redundant

Redundancy State: Redundant

Power Capacity: 7400 Watts DC

Present Power: 3171 Watts AC

Part Number   : 412142-B21

Spare Part No.: 414055-001

Serial Number : O985MP5849

UUID          : 09O985MP5849

Manufacturer  : HP

Firmware Ver. : 4.30 Jul 08 2014

Hw Board Type : 0

Hw Version    : B1

Loader Version: U-Boot 1.1.1 (Nov 15 2010 - 10:00:47)

>SHOW POWER

Power Mode: Redundant

Dynamic Power: Disabled

Set Power Limit: Not Set

Power Capacity:              7400 Watts DC

Power Available:                0 Watts DC

Power Allocated:             7400 Watts DC

Present Power:               3171 Watts AC

Power Limit:                 8998 Watts AC

******************

******************

Max Input power is 9000 which is 2250 x 4

So perhaps you are set in Power Supply Redundancy mode (N+1) and not AC Redundant (N+N)

But N+1 with 4 would indicate you have 5 PSUs online which doesn’t match your 6 below.

Anytime you see DC, that’s internal power and not wall power.

Anytime you see “Allocation” that’s how much the chassis thinks it could draw if every component went to 100% at the same time.

So this section is key:

Enclosure Bay Output Allocation:

Bay               Power Allocated (Watts DC)

-------------     --------------------------

Devices                   6520

Interconnects          +   380

Fans                   +   500

-------

=  7400

So that says your blades think they could, combined, consume 6520W if they all went crazy.

Interconnects would take 380

Fans would take 500 (50W x 10 Fans)

Because 7400 is more than 6750 (2250x3), you would not have been allowed to power on Blade 16 and probably not 15 either.

So someone changed the Power Redundancy mode to N+1 which changes the allocation maximum, and then the last 2 blades come up.

This is not a bad thing, because there seems to be a wild swing between actual usage of a normal blade server and what we consider the Max/Allocation to be.

For instance, when you ran the commands, here is your actual usage:

Enclosure Input Power Summary:

Enclosure              Watts AC

-----------------      --------

Present Power             3170

So you can see from the wall, including some loss due to AC/DC conversion, you are only drawing 3170 which is way less than 6750 and means you are still technically N+N redundant.

But back to what I said before, either my math is off, or one of your power supplies is.

Actually, I wonder now if they are deregulating the number automatically.

5 PSUs (N) x 2250 = 11,250

In North America, you are only supposed to use 80% of that consistently (you can spike higher)

11250 * 0.80 = 9000

So perhaps you don’t have only 5, you have 6 and the OA is doing the 80% rule automatically for you.

Because you showed below you most definitely have 6 and they are all online.

Hope that helps explain some of these numbers.

Thanks,

Dan