PMBus

Power Management Bus is an Open Standard Protocol that specifies the communication of power supplies (Power Conversion) with other devices (such as mainboards or IPMI/Remote Management Chips) via I²C data bus. Administrators can query information on the power consumption as well as the condition of the power supplies for servers with PMBus-compatible power supplies. In this article, we explain how this is possible.

Provided information

PMBus-able power supplies can provide the following information:

• input voltage and power (Ampere)
• output voltage and power (Ampere)
• temperatures (up to three sensors)
• fan speeds (up to two fans)
• duty cycle
• switching frequency

Querying information on IPMI webinterface

For servers with Supermicro mainboards and PMBus-compatible power supplies, it is possible to query information on the power consumption in the IPMI webinterface under Server Health -> Power consumption:

• 
  Power consumption (1/2)
• 
  Power consumption (2/2)

Querying information on the operating system

PMBus information can also be queried on the command line of the operating system via certain software programs, for example FreeIPMI.

Information on this can be, for example, found in the article Intel Node Manager power measurement using FreeIPMI sowie im Artikel IPMI Power Supply Sensor.

More information

• PMBus Power System Management Protocol Specification Revision 1.2 (www.pmbus.org, 06.09.2010)
• Introduction to PMBus: Power-Manager in action (www.elektroniknet.de, 06.08.2018)

Author: Werner Fischer Werner Fischer, working in the Knowledge Transfer team at Thomas-Krenn, completed his studies of Computer and Media Security at FH Hagenberg in Austria. He is a regular speaker at many conferences like LinuxTag, OSMC, OSDC, LinuxCon, and author for various IT magazines. In his spare time he enjoys playing the piano and training for a good result at the annual Linz marathon relay.

Translator: Alina Ranzinger Alina has been working at Thomas-Krenn.AG since 2024. After her training as multilingual business assistant, she got her job as assistant of the Product Management and is responsible for the translation of texts and for the organisation of the department.