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C6100 PSU's show unbalanced current load
Hi,
I have a few C6100's which show an unbalanced current load on the PSU's. The sensors read out by ipmitool shows the following:
FCB FAN1 | 4300 RPM | ok
FCB FAN2 | 4300 RPM | ok
FCB FAN3 | 4300 RPM | ok
FCB FAN4 | 4300 RPM | ok
PEF Action | 0x00 | ok
WatchDog2 | 0x00 | ok
AC Pwr On | 0x00 | ok
ACPI Pwr State | 0x00 | ok
FCB Ambient1 | 16 degrees C | ok
FCB Ambient2 | 0 degrees C | ok
CPU1Status | 0x00 | ok
CPU2Status | 0x00 | ok
PS 12V | 12.21 Volts | ok
PS 5V | 5.02 Volts | ok
MLB TEMP 2 | 46 degrees C | ok
MLB TEMP 3 | 38 degrees C | ok
Processor 1 Temp | 25 degrees C | ok
MLB TEMP 1 | 42 degrees C | ok
Processor 2 Temp | 27 degrees C | ok
STBY 3.3V | 3.35 Volts | ok
PS Current | 7 Amps | ok
SEL Fullness | 0x00 | ok
PCI BUS | 0x00 | ok
Memory | 0x00 | ok
VCORE 1 | 1.03 Volts | ok
VCORE 2 | 0.89 Volts | ok
NM Capability | Not Readable | ns
Security | 0x00 | ok
PSU 1 AC Status | 0x00 | ok
PSU 2 AC Status | 0x00 | ok
PSU 1 Present | 0 unspecified | nc
PSU 2 Present | 0 unspecified | nc
PSU 2 POUT | 3 Amps | ok
PSU 1 POUT | 27 Amps | ok
As you can see the last two entries show that the power output for PSU1 is 27 Amps, and PSU2 is 3 Amps. On most of my machines, these numbers are very close to being equal. Is there an internal setting which switches these Power Control Boards from balanced to backup mode? Meaning that one is being used solely as a warm spare, instead of an even load balancing. When we remove PSU1, PSU2 takes over just fine and provides all required power. The problem is that we expect the load to be balanced, and if the system is not, it creates alarms for us since effectively one supply is full on, and the other is off. Has anyone else seen this problem and found a solution, or must I have the Power control boards replaced? Also, how does the FCB interact with the power control boards, and could this also need replacing? Thanks for any help
DELL-Daniel My
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July 11th, 2013 10:00
Hello matt2me
The C6100 does not have a load balancing feature. The only mode for the PSUs is redundant. This server is operating normally. When the power supply is not being used it should not have a large amount of power output. I would suggest making sure your other C6100s have current BMC and PSU firmware. If both PSUs in those units are outputting the same amount of power then they are unnecessarily increasing your electric bill.
Thanks
Matt2Me
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July 15th, 2013 10:00
I have about 500 chassis which balance the load at about 13-15 Amps per supply. I only have 2 or 3 chassis which seems to hit the rail on one PSU. I was told that indeed these did load balance by default. Could this be an undocumented feature of the C6100?
DELL-Daniel My
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July 17th, 2013 11:00
After extensive digging I think I found the answer. I was incorrect about the power supplies load balancing. The power supplies do load balance, and this is what appears to be happening with your servers:
If the combined power draw among all nodes are less than 1100 watts then it will only use 1 power supply. This will allow you to remove a power supply and the system will continue running. If the combined draw is over 1100 watts then it will load balance across the two power supplies. It would appear that your 2-3 chassis that are using mostly 1 PSU are drawing less power than the other servers.
Sorry about the confusion in my first post.
Thanks