Open Compute Developing Wider Rack Standard

1sockchuck writes "Are you ready for wider servers? The Open Compute Project today shared details on Open Rack, a new standard for hyperscale data centers, which will feature 21-inch server slots, rather than the traditional 19 inches. "We are ditching the 19-inch rack standard," said Facebook's Frank Frankovsky, who said the wider design offered better heat removal and a unified approach to power, including a 12 volt busbar. The Open Compute Project, developed by Facebook to advance open source hardware design, believes an open approach can avoid the mistakes of blade server chassis design."

Comments

Clouseau: The case is solv-ed

[alphatel]

So put the server power supply on the outside, basically.

metric?

[SkunkPussy]

The first mistake is that they are still talking in inches instead of metric units.

Re:metric?

[Anonymous Coward]

Arguing metric vs. imperial units is pretty much the epitome of bikeshedding.
We can do arithmetic nowadays.

Re:metric?

[Christian Smith]

Arguing metric vs. imperial units is pretty much the epitome of bikeshedding.
We can do arithmetic nowadays.

We can do, but people (even rocket scientists!) still get it wrong: http://en.wikipedia.org/wiki/Mars_Climate_Orbiter

Technical issues should use SI units.

Re:metric?

[Anonymous Coward]

http://en.wikipedia.org/wiki/Mars_Climate_Orbiter Technical issues should use SI units.

The Mars Climate Orbiter was a case of someone not labeling their units. The unit system wasn't the problem.
Secondly SI isn't always the best unit of measurement for performing calculations. In plasma physics we use eV in stead of joules for energy because it simplifies our work. In astro physics measuring distances in the SI unit of length, the meter, is impractical. If you are doing anything with relativistic electro magnetism, it's best to do your calculations in cgs because it eliminates useless constants.

Re:metric?

[MetalliQaZ]

Actually, I think deliberations over the color of a bike shed is the epitome of bikeshedding.

Re:metric?

[richardkelleher]

The first mistake is that they are still talking in inches instead of metric units.

This was my thought exactly. If we continue to build new standards around obsolete measurement systems we are just pandering to the Luddites. It is time to move America forward into the 19th century. If we can't engineer for the 21st century, we should turn the creation of standards over to people can.

Re:metric?

[David Chappell]

The first mistake is that they are still talking in inches instead of metric units.

I would imagine that the reason is that 21 inch racks are already a standard. They are widely used in telephony. Introducing a third standard (say 55 cm racks) would likely complicate things for little gain. Better to just call them 5334 mm racks.

This has already been done repeatedly in engineering. When I visit Europe (I am an American) I see things in Imperial units all around me, but most of the time nobody but me knows that they are. 6 mm steel cable? Why not 5 mm? Because 6mm is 1/4 inch. While is their 900 grams of buckwheat in this bag rather than 1000 grams? Because it is a two pound bag filled eight grams short. Railway gage in the former Soviet Union? 1524 mm. Yup, thats five feet. See that 1220x2440 mm sheet of plywood. Yup, 4 by 8 feet.

This by the way is why it is so hard to convince Americans that they should switch the building and engineering trades to the metric system. All our building materials are sized on Imperial units. Converting these dimensions to oddball metric sizes would mean that builders would need to memorizes all sorts of weird dimensions and carry pocket calculators to figure out where the center of something is. There have been many serious attempts to do engineering projects in metric units. First they find out that they can't get materials in even metric dimensions. Then the vendors ask what they mean when they order 914.4 mm doors. Then the builders ask to have the drawings converted into 'the real measurements'. It begins to seem too much like masocism and on the next project they go back to units everybody understands.

Many professions and markets have converted to metric in the US. Medicine mostly has. So has alcohol distribution. So have laboratories. So have our automobiles. But, I don't see any way for the building trades to convert.

The metric system is clearly superior in scientific contexts. There the argument about ease of conversion is powerful. However this argument is meaningless in daily life. The only unit conversion the average person does is feet to inches. You don't need to know how many feet are in a mile in order to know whether you are exceeding the speed limit.

I have found one use for metric units in daily life: increasing ones 'geek cred'. Since expressing dimensions in metric units is a form of elitist obfuscation, it is a great way to be annoying.

Re:metric?

[Anonymous Coward]

But units wouldn't need to be labeled if everybody used the same system. The continued existence of the zombie Imperial system is the root cause of the problem.

Which is why SI has a number of accepted units. You'll note that both the eV and the astronomical unit are there, but not the feet or yards used by Lockheed to send a rocket past Mars.

ALWAYS LABEL UNITS! This was the ONLY cause of the problem with the mars orbiter. If Lockheed used kilometers as their units instead and Nasa assumed meters the probe still would have had problems. If I tell you I have an energy of 5 does that mean 5 eV or J? You don't know if I don't label it.

Re:metric?

[Shompol]

Secondly SI isn't always the best unit of measurement for performing calculations.

While Imperial units are always the worst.

2" shim market

[RichMan]

I detect a few years of market window for rails with 1" shims attached (19+2x 1" = 21) to allow old servers to wedge into the new racks.

Server width is changing Rack Width isn't

[darthcamaro]

There is a big distinction that you need to understand here, the Width of the Server chassis is changing, not the width of the rack itself. The outer dimension of the Server Rack is staying at 24 inches. The REAL problem was a bogus amount of extra cruft in the rack design that is going to be eliminated to make way for the wider servers.

Re:Server width is changing Rack Width isn't

[IGnatius T Foobar]

That "extra cruft in rack design" is where your cables go. I have an 18,000 sqft data center over here and I can tell you from experience that what you call "cruft" isn't nearly enough space for all of the cables once things start getting dense. We are actually considering 23" (telecom standard) racks with 19" rails in them for cabinets that aggregate the networking gear, just for this reason.

But oh no, far be it from Facebook to actually work with the industry. They screwed up the Internet and now they're going to screw up your data center.

Why invent a new standard?

[Anonymous Coward]

Why invent yet another new standard when there's a perfectly good one already in use, with lots of inventory in place?

Telecom has used 23" racks for years. There are standard adapters already available to mount 19" hardware in a 23" rack. 23" racks are already available in the marketplace.

Further, why 12Vdc? Telecom has been using DC plant for decades and there is a ton of existing 48Vdc equipment on the market. There area existing cabling standards for all this as well.

Just seems like an attempt to fracture the market and create an opportunity to solve a problem that's already been solved.

Re:Why invent a new standard?

[rickb928]

It's not about the resistive losses, mate.

First, eliminating power supplies at each server eliminates multiple point heat sources. One honking rectifier stack somewhere does the job. Cool that separately, and maybe even more efficient conversions, though the jury is still out on that for me. Honking-er bus bars will not be as efficient as AC distribution, but the losses will be tolerable. Remember the stack? Getting that cooled outside the server room is useful.

Using 48VDC makes a lot of sense just because there is a pile of telco equipment made to do that, and well understood. It will have to be regulated at the server level anyways, and the current goes down also.

But then again, it's not about being compatible, nor even evolutionary. This is a revolution, and if the old guard can't be enslaved, it must be killed off. So telco standards are out of the question. Besides, those extra 2 inches.

Re:Why invent a new standard?

[rev0lt]

Using 12VDC on any type of system that uses more than a few hundred watts is insane

Like in a car?

Re:Why invent a new standard?

[marcosdumay]

Touching the 12Vdc @ 500A copper bar bus will kill off some of the new guard too.

How? Are you trying to tell me that those 500A will run inside a person's body when you apply 12V of potential diference on it? You mean a person's body has 24m Ohm of total resistance?

The 48V bus would kill much more people, even if less current flowed through it. A person only needs a few mA to die.

Re:Why invent a new standard?

[Grishnakh]

They should just dump the -12V requirement. They've had chips available for years that can supply +/-12V for RS232 ports; I believe the MAX232 from Maxim is one of them: you connect it to 5V data lines from your microcontroller, give it 5V for power, add in four capacitors, and it outputs +/-12V RS232 signals. I was using this chip back in the late 90s for embedded equipment that needed RS232 connectivity so we wouldn't need a power supply with -12V.

They should also dump the 3.3V requirement. AFAIK, that's only used for SATA hard drives, and even there most don't use it because they couldn't count on people actually having 3.3V-compliant power supplies, as many users were installing the (then-new) SATA drives into older computers and using Molex-to-SATA power adapters. 3.3V has a huge drop over any distance, so it makes much more sense to just use a DC-to-DC convertor at the point of use to convert 12V to 3.3V. Now that even CPUs want 12V instead of 5V, and high-end video cards have their own 12V connectors, it seems to me they should just dump all the other requirements altogether, and make a PC power supply only produce +12V, and have the motherboard and drives use their own DC-to-DC converters to produce whatever voltages they require.

Ok, then.

[Impy the Impiuos Imp]

> Open Compute Developing Wider Rack Standard

Well, programmers have been getting fatter over the years. I suppose this applies to the female ones, too.

Re:Wow. Awesome advances in technology!

[networkBoy]

As soneone responsible for machine infrastructure, this is a big deal.
21" racks means that I have to change the layout of my lab. Currently we have the mandatory 42" aisle (or whatever ADA requires) running the length of the lab, with banks of racks pedistileing (sp?) out from the wall with power and data. If all the racks were 2" wider I'd lose a rack in each row, so unless these machines improve density... it's a no sell for me.

RTF spec. - benefits and potential issues.

[gstrickler]

The spec can be downloaded from here

At first, I thought this sounded like a stupid idea too. Then, I read the spec. They're not just changing the width of the equipment area, and it's not just an extra 2".

External width is unchanged from the 19" rack standard, it's still nominally 23.6". No replacement of floor tiles or room redesign necessary.

Equipment width is increased from ~17" (on a 19" rack) to 21", it's allows 4" wider equip.

Power is handled in 3 "zones" per tower. Each power zone provides 12.5V DC power on each of 3 independent pairs of power rails, No AC power supply is required for each piece of equipment, but they will need DC-DC converters and VRs to supply the voltages needed for their specific components. That saves some space on each device, and provides a slight improvement in efficiency. Because this is standardized worldwide, there is no need for each device to have different power circuitry for different countries.

Because a zone can have triple power rails, devices can use 1, 2, or 3 power rails to provide whatever level of redundancy is appropriate.

Space for switches is included in each rack, along with power monitoring/reporting circuitry per rack.

Battery backup power can either be built into the power supply for each zone, or supplied from a separate battery rack.

The specification allows for many AC or DC power sources, this is the only significant part of the spec that will vary by country as the power units will need to support the available AC and/or DC supply.

All devices are to be hot-plug compatible.

So, it does have a lot of advantages.

Here are the concerns I have with it:

All power rails appear to be exposed. While they are on the back, this could be a significant safety (personnel and/or fire) issue. Considering that you can up to 500A @ 12.5V DC running through the zone power rails, and potentially more for the main cabinet DC power rails, exposed seems like a bad idea.

The standard allows depths from 36" to 48". With the way devices connect to power rails on the back, it looks like this means you will need to use devices designed for the specific depth of your rack, or use a shim to extend the device to match the depth of the rack. I believe they should standardize on one, or at most 3 depths, and have a standard set of shims to connect the devices designed for the shorter depths to fit the deeper racks.

Re:Wow. Awesome advances in technology!

[Doc Hopper]

That's covered in the article. 21" racks within the current 24" standard rack size. By eliminating cable mass in favor of bus-bars, you gain the two inches "free" in your rack footprint. If the rack's designed right, you could even keep the same seismic bracing.