UCS X-Sequence- The Way forward for Computing – Half 2 of three

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UCS X-Sequence- The Way forward for Computing – Half 2 of three

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As we transfer to  widescale deployment, we imagine that  UCS X-Sequence  architectural message is resonating extraordinarily nicely as deployment suggestions has been unbelievable.
Within the first put up a part of the weblog collection, we mentioned how heterogeneous computing  is inflicting paradigm shift in computing shaping UCS X-Sequence  structure. On this weblog we’ll talk about the electromechanical facets of the UCS X-Sequence structure.
Formfactor stays fixed for a life cycle of the product therefore  electromechanical facets that form the enclosure design are  very essential in design part.
Electro-mechanical Anchors
A number of the anchors are:

Socket density per ‘RU”.
Reminiscence density
Backplane much less IO
Mezzanine  choices
Volumetric area  for  logic
Energy footprint & supply
Airflow (Measured as CFM) for cooling

Socket and reminiscence density is essential when evaluating totally different vendor’s product and on the whole is a sign of a how effectively the platform mechanical has been designed in a given “RU” envelop.   The ratio of  volumetric area required for mechanical integrity vs  logic is one other essential  standards.  These criterion helped us to zero all the way down to 7RU as chassis top &  on the similar time providing extra  volumetric area obtainable for logic in comparison with the  related “RU” design from business.
Earlier technology of compute platforms relied on Backplane for connectivity.  UCS X-Sequence, doesn’t use backplane however direct join IO Interconnects.  Because the IO expertise advances , nodes and the IO Interconnect  might be upgraded  seamlessly as the weather that must be modified are modular and never fastened on backplane.   Because the IO Interconnect pace will increase its attain decreases making it tougher and tougher to scale in electrical area. UCS X-Sequence has been designed with hybrid connector method that  helps  electrical IO by default and be prepared for optical IO in future.  This  optical IO possibility is optimized for intra  chassis connectivity. Direct join IO with out a backplane helps to cut back the airflow resistance and helps to take away the warmth from inlet to outlet effectively.
Energy distribution
Rack energy density per “RU” is hitting  1KW and shortly will transcend that.   Majority of the present server design makes use of nicely established 12V distribution to simplify down conversion for CPU voltages. Nonetheless   as present density will increase  utilizing 12V distribution would add to the  connector prices, PCB  layer depend and routing challenges.  UCS X-Sequence, seeing the necessity for subsequent technology of  server energy necessities selected to make use of larger voltage distribution of 54V as a substitute of 12V. Larger voltage distribution  reduces present density by 4.5 occasions and ohmic losses by 20 occasions decrease in comparison with 12V.  Shifting from 12V to 54V DC output helps in simplifying predominant PSU  design and makes onboard energy distribution extra environment friendly.
Server Energy Consumption
We’re seeing  CPU TDP (Thermal Design Energy)  growing by 75-100W at a  2 12 months cadence stage.  Compute nodes will quickly begin seeing 350W per socket and so they have to be prepared for 500W+ by 2024.   A  2 Socket  server with GPU and storage  requires near  2.2KW energy not accounting for any  distribution losses.   To chill this  2 Socket server, fan modules alone  will devour  round 240W ,  11 % of complete energy.  Factoring distribution efficiencies at every intermediate stage of conversion from AC enter  we’re round 2.4KW energy draw. So, in a RACK servers with 20 x 2RU servers ,  Fan energy alone will devour 4800W !!.   Modular blade platform  like UCS X-Sequence  with its centralized cooling  and greater followers,  provide a lot larger CFM’s at a  decrease energy consumption.  Nonetheless fan  energy consumption  is certainly  turning into substantial portion of the full energy price range.

Cooling
Advances in semiconductor and magnetics permits us to offer extra energy  within the life time of chassis. Nonetheless, it’s troublesome to drag off a dramatic improve on airflow ( measured as fan CFM) as technological advances are sluggish & incremental.  Moreover,  price economics dictates  use of passive warmth switch methods  to chill the  CPU in Server. This makes defining fan CFM necessities for cooling the compute nodes a multi variable drawback.
Not like normal rack design which makes use of unfold core CPU placement,  UCS X-Sequence makes use of shadow core  design precept complicating cooling even additional.

Banks of U2/E3 storage drives with energy upwards of 25W every and accelerators   on entrance aspect of the blade will  prohibit air going to the CPU in addition to it is going to pre-heat air.
UCS X-Sequence design approached these challenges holistically.  At the beginning  is  the  growth of the state-of-the-art  fan module delivering the category main CFM.  The opposite being  the dynamic energy administration  coupled with  fan management algorithm that can adapt & evolve as cooling demand grows and ebbs.  Compute  nodes are designed with excessive and low CFM   paths channeling applicable airflow for cooling. Moreover,  energy administration choices supplies buyer with configurable knobs to optimize for fan energy  or excessive efficiency mode.
Emergence of Alternate Cooling Applied sciences
Spot cooling of CPU/GPU at 350W is approaching limits of air-cooling  Doubling airflow ends in 30% extra cooling however it could add 6-8 occasions extra fan energy with  diminishing return.
Knowledge facilities usually are not but prepared for liquid cooling on wholesale foundation.  Immersion cooling  requires full overhaul of the RACK.  Hyperscalers will lead  early adoption cycle  and  finally Enterprises prospects will  get there however the  tipping level from air to liquid cooling continues to be unknown.  Air cooling will not be going away as we nonetheless want to chill reminiscence, storage  and different elements that are operationally troublesome  for liquid cooling. We have to accumulate extra information and reply following essential questions earlier than  liquid cooling turns into engaging.

Do we actually want  liquid cooling for all RACKs or solely few RACKs which hosts excessive TDP servers.
Is liquid cooling extra for inexperienced area deployments as a method to cut back fan energy/acoustics  than for high-TDP CPU/GPU enablement?
 Any Compliance/mandates  that  targets vitality discount  by sure dates in information middle?
TCO evaluation of fan energy saving vs  the full price of  liquid cooling  deployment?
Is buyer OK to spend extra on fan energy cooling than retrofitting the infrastructure for liquid-cooling?
Is liquid cooling going to  assist  deploy extra  excessive TDP servers with out upgrading  energy to  the RACK?

For ex: Saving 100W per 1U  in fan energy interprets to  3.6KW (36x 1U server) extra obtainable energy

UCS X-Sequence  nevertheless does help  a hybrid mannequin – a mixture of air/liquid cooling when air cooling alone will not be ample. Be careful for extra particulars in upcoming blogs on liquid cooling in UCS X-Sequence.
Within the subsequent weblog, we’ll elaborate on traits drove the UCS X-Sequence inner structure.
 

Assets
UCS X-Sequence – The Way forward for Computing Weblog Sequence – Half 1 of three

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