6500 power modes

[Jon Marshall]

It's been a while since I had to do this and I have obviously forgotten most of it but I am having trouble understanding the below output - 

DCP-6509A-DC1-CO#sh power
system power redundancy mode = redundant
system power total = 3795.12 Watts (90.36 Amps @ 42V)
system power used = 1307.88 Watts (31.14 Amps @ 42V)
system power available = 2487.24 Watts (59.22 Amps @ 42V)
Power-Capacity PS-Fan Output Oper
PS Type Watts A @42V Status Status State
---- ------------------ ------- ------ ------ ------ -----
1 WS-CAC-3000W 2771.16 65.98 OK OK on
2 WS-CAC-4000W-INT 3795.12 90.36 OK OK on
Note: PS2 capacity is limited to 2940.00 Watts (70.00 Amps @ 42V)
when PS1 is not present
Pwr-Requested Pwr-Allocated Admin Oper
Slot Card-Type Watts A @42V Watts A @42V State State
---- ------------------ ------- ------ ------- ------ ----- -----
2 WS-X6748-GE-TX 325.50 7.75 325.50 7.75 on on
3 WS-X6748-GE-TX 325.50 7.75 325.50 7.75 on on
5 WS-SUP720-3BXL 328.44 7.82 328.44 7.82 on on
6 (Redundant Sup) - - 328.44 7.82 - -
system auxiliary power mode = off
system auxiliary power redundancy operationally = non-redundant
system primary connector power limit = 3780.00 Watts (90.00 Amps @ 42V)
system auxiliary connector power limit = 0 Watt
system primary power used = 1307.88 Watts (31.14 Amps @ 42V)
system auxiliary power used = 0 Watt

so the system says it has 2 PSUs and both are operational and it is running in redundant mode.

Two things are confusing me -

1) this line - "system auxiliary power mode = off".  I did a quick search and an answer was that it was because there was only one PSU in the chassis but this is clearly not the case from the above (and from a visual check) so what exactly does it mean ?

2) the docs say that to run in redundant mode each power supply must be the same wattage but the above PSUs aren't and yet it is saying it is running in redundant mode.

Can someone help clarify. 

Jon

[Reza Sharifi]

Hi Jon,

Hope you are doing well. It is has been a long time.

I think the switch is configured in redundant mode but since the power supplies are not the same, they are not redundant . If your power supplies had the same wattage, you would see a line like this when you issue sh power. 

xxxxxxx#sh power switch 1
Switch Number: 1
system power redundancy mode = redundant
system power redundancy operationally = redundant(3+1)
system power total = 8399.56 Watts (161.53 Amps @ 52V)
system power used = 2629.12 Watts (50.56 Amps @ 52V)
system power available = 5770.44 Watts (110.97 Amps @ 52V)
Power-Capacity PS-Fan Output Oper

Please note I don't have any 6500 to test with. This output is from a 6807 that has 4 power supplies.

HTH

[Jon Marshall]

Hi Reza 

I'm good but obviously forgetting some of my 6500 knowledge :).

Yes I am beginning to think the same to be honest, so if you don't mind some follow up questions - 

1) If it is not actually running in redundant mode if the active PSU fails then would it still use the remaining PSU as that PSU can provide enough power ? 

2)  If PS2 fails and PS1 does not take over then should I be running in combined mode instead ie. do I need to change it for both PSUs to be used or would PS1 take over anyway. 

3) Do you know what this part of the output means - 

Note: PS2 capacity is limited to 2940.00 Watts (70.00 Amps @ 42V)
when PS1 is not present

it is obviously using PS2 at the moment but why would it be limited without PS1

Sorry for all the questions but I am really not following what that output is telling me.

Jon

[balaji.bandi]

You have un equival PSU install it is not the best practice, even though it accepts.

1 WS-CAC-3000W 2771.16 65.98 OK OK on
2 WS-CAC-4000W-INT 3795.12 90.36 OK OK on
Note: PS2 capacity is limited to 2940.00 Watts (70.00 Amps @ 42V)

at the moment your device only using below power  level :

system power used = 1307.88 Watts (31.14 Amps @ 42V)

So 3K W power supply good enough to support here(based on the modules installed) . even though your 4KW PSU fails.

Only issue come here when you fully populated the Kit with all the solts with different modules, and upgrade to SUP-2T. 

As long as you are not adding any modules you are good here.

But suggestion is always to have same PSU and recomended, if i were you and have concern i will replace other 3KW PSU with 4KW to be safer side.

[Jon Marshall]

I have enough power yes but as I said to Reza, because it is not in redundant mode and it has not been configured in combined mode what happens if the active PSU fails ? 

Jon

[balaji.bandi]

I have not tested, But i Believe Cisco uses same technology all over the products line of switching.

if the PS1 Fails you should be fine Technically - since you have not over loaded PSU Powerwise.

By saying the keeping my experience with 3850 with un even PSU installed. it will take it..when the higher PSU as primary fails, it will move to next PSU Lower Size, it was not given enough power to rest of PoE Ports - this was tested).

I may have 6500 in stock, we will test when i get chance and get back to you soon.

[Reza Sharifi]

Hi Jon,

1) If it is not actually running in redundant mode if the active PSU fails then would it still use the remaining PSU as that PSU can provide enough power ?

I have never tested that before. Unfortunately, I don't have any 6500 with unequal PSUs to test with.

2)  If PS2 fails and PS1 does not take over then should I be running in combined mode instead ie. do I need to change it for both PSUs to be used or would PS1 take over anyway. 

"power redundancy-mode combined" is global config and I think it will apply to both PSUs. 

Note: PS2 capacity is limited to 2940.00 Watts (70.00 Amps @ 42V)
when PS1 is not present

I am confused at this output as I am not sure why if PSU 1 go down, it will lower the amperage/wattage from 90 to 70 and 3780 to 2940 for PSU2

90*42=3780 is the capacity of ps2

And 70*42=2940 which is the capacity of ps1

Sorry, this is not much of help here.

Reza

[Reza Sharifi]

Hi Jon,

I also found this:

https://community.cisco.com/t5/switching/6000w-power-supply-limited-to-2940-watts-only/td-p/1141255

HTH

[Jon Marshall]

Reza 

Thanks, that explains the message I was seeing. 

The big question is I suppose what happens if the active PSU fails, does it use the other one or does it reboot. 

I may be better to put into combined mode, speaking of which the docs say you can switch between redundant and combined with no downtime. 

Have you ever done it ? 

Jon

[Leo Laohoo]

---

@Jon Marshall wrote:

Note: PS2 capacity is limited to 2940.00 Watts (70.00 Amps @ 42V) when PS1 is not present

---

I must admit I've never seen an output like this before.  

PS1 is a 3K power supply and PS2 is a 4K power supply (frankly, I've never seen a 4K power pack before).  

Because of the difference of the two, the "lowest common denominator" factor will always be used:  Since the "smallest" power pack is 3K, then the 4K power pack is "down rated" to act like a 3K.  

[Jon Marshall]

Hi Leo 

It's a new one to me as well :) 

I am just concerned about what happens if the active PSU fails. 

Jon

[Jon Marshall]

Guys 

On a related note, I have just had to swap out a failed PSU from a system that was running 2 x 2500W in redundant mode. 

The only spare PSU I had was a 3000W and according to the docs you should be able to insert it and it will power up and then take over as it has the higher power capability but it hasn't powered up and the system shows it is offline. 

I have had failed fans and PSUs before but this suggests it could be the chassis itself. 

Any of you ever seen anything like this or have any non service affecting things I can try ? 

Jon

[Reza Sharifi]

Hi Jon,

Can you take a flashlight and look at the pins where you insert the power supply to make sure no pins are bent?

I once had this issue in 2008 where we replaced multiple power PSUs on 6509-V-E  chassis with no luck and finally replaced the chassis to fix the PSU problem.

Thanks,

Reza

[Jon Marshall]

Hi Reza 

Going to try that later today, see what the state of the pins are. 

I just want to make absolutely sure it is a chassis issue before having to swap it out as that is quite a big job.

Jon

[Leo Laohoo]

---

@Jon Marshall wrote:

The only spare PSU I had was a 3000W and according to the docs you should be able to insert it and it will power up and then take over as it has the higher power capability but it hasn't powered up and the system shows it is offline. 

---

Very rare to see a chassis fault. 

So when inserting and attempting to power up the replacement PS, what logs come up (if any)?