Cisco Unified Computing System: Power and Physical Requirements

14 06 2010

So the day has finally come…your new UCS gear is scheduled to arrive, but what to do about getting it installed in your data center?  The following resources outline the necessary information for determining the power and physical requirements to support a Cisco UCS server environment.

The physical requirements are pretty straight forward.  A 5108 UCS blade chassis occupies 6U of rack space and is designed to fit in a standard 19 inch rack.  The 6120XP Fabric Interconnects require 2U of rack space, 1U per switch in an HA pair, and the 6140XP Fabric Interconnects require 4U of space, 2U per switch.  Each is also designed to fit in a standard 19 inch rack.

The weight of the overall solution should be taken into consideration when planning the location in the data center.  A fully populated chassis along with 2 6120XP Fabric Interconnects weighs around 424 lbs, and therefore should be installed at the bottom of a rack when possible.

The 5108 chassis can have a maximum of 4 power supplies, and the number of supplies is dictated by the number of populated blades, or by the amount of power redundancy needed.  In general Cisco recommends 2 single phase, 200-250vAC 20A circuits per 5108 chassis, with each circuit feeding either 2 or 4 of the power supplies based on the desired power configuration.  The power supplies can be installed in the following configurations:

-Non-redundant – In a non-redundant scheme, all power supplies are active and distribute the load evenly.  Small installs requiring less than 2500W can use a single power supply, but that would be bad practice as you would have no redundancy.  Most implementations  require 2 or more power supplies in a non-redundant configuration.

-N+1 Redundancy – In this format there is a minimum number of power supplies in the chassis to satisfy non-redundancy, plus 1 additional power supply for redundancy.  All power supplies active in a N+1 redundancy are active and supporting the load.  Any extra, installed power supplies are labeled unnecessary and therefore are powered off by UCS Manager.  In the advent of a power supply failure, the extra power supply will be activated automatically.

-Grid Redundancy – This configuration is used when there are redundant circuits and/or PDUs available for powering the environment.  Grid redundancy allows for protection not only from a power supply failure, but also from a PDU failure by having power supplies on each circuit.  In this scenario, 2 power supplies are recommended for configurations requiring 2500W or less, and 4 power supplies for those over 2500W.

The 6120/6140XP Fabric Interconnects can have either 1 or 2 power supplies configured, the later of course being the best practice configuration.  Each power supply requires 120V, single phase power, and consumes around 450W.  Cisco recommends having redundant 15A circuits for supplying power to the Fabric Interconnects.

There are several plug options for both components, which are listed below:

5108 Chassis Power Cables

6120/6140XP Fabric Interconnect Power Cables

Determining actual power requirements for your particular environment can be accomplished by contacting your Cisco partner of choice.  UCS certified partners have access to the UCS Power Calculator tool.  However, listed below is an example breakdown of power requirements:

The last major area of consideration with the hardware installation is cooling capacity.  Both the 5108 chassis and 6120/6140XP Fabric Interconnects use front-to-back airflow for cooling, meaning both are designed to function in a hot aisle/cold aisle layout.  In general the Btu/hr breakdown for the individual components is as follows:

-Cisco UCS 6120/6140XP Fabric Interconnects – Up to 1534 Btu/hr

-Cisco UCS 5108 Blade Chassis – Up to 1364 Btu/hr

-Cisco UCS B200 Half-width Blade (Per blade) – Up to 1347 Btu/hr

Heat output for a complete, fully populated single chassis system is around 15,000-16,000 Btu/hr.




One response

18 08 2010
Some UCS Links - - The weblog of an IT pro specializing in virtualization, storage, and servers

[…] Cisco UCS Server Pools: Use Cases Placement of mezzanine adapters in full width blades Chassis Discovery Policies in UCS Cisco UCS Server Pools: Configuration Why Cisco UCS is my ‘A-Game’ Server Architecture Verifying FEX Uplink Pinning in Cisco UCS Cisco UCS Pools In Depth Myths and Restrictions of the Cisco UCS Correction to L2 Forwarding Rules post UCSM 1.3(1c) Released! Cisco UCS Enhancements in Firmware 1.3 Cisco Unified Computing System: Power and Physical Requirements […]

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