The Next Generation Open Compute Hardware: Tried and Tested
by Johan De Gelas & Wannes De Smet on April 28, 2015 12:00 PM ESTBenchmark Configuration: Leopard Under Stress
To evaluate how the Leopard platform performs, we put it against two Haswell-powered alternatives: Intel's Decathlete reference platform, and a Dell R730. Please note that we did not have a power supply similar to the Dell R730 in-house, and PSUs with comparable efficiency failed to keep the 12V rail high enough, so the PSU of a Freedom node was used. Normally Leopard is powered by a power shelf with better efficiency, so power usage should be lower when deployed in a complete OR setup as compared to ours.
Leopard coupled to Freedom PSU
To test the servers with a workload similar to what is being run at Facebook, we selected the following benchmarks:
- OLAP: a database workload built by a news aggregator website, putting stress on most of the system (CPU, RAM and disk)
- ElasticSearch: search queries on an index of Wikipedia, a CPU and memory intensive workload
| System | Intel CPU | RAM | Disk | PSU |
| FB Leopard | E5-2670 v3 @ 2.30GHz | Samsung 256 GB DDR4 2133MHz LRDIMM M386A4G40DM0-CPB | Intel SSD DC S3500 240GB | PowerOne SPAFCBK-01G |
| Dell R730 | E5-2670 v3 @ 2.30GHz | Samsung 265 GB DDR4 2133MHz LRDIMM M386A4G40DM0-CPB | Intel SSD DC S3500 240GB | Dell D495E-S1 495W 80Plus Platinum |
| Intel Decathlete v2 | E5-2670 v3 @ 2.30GHz | Samsung 265 GB DDR4 2133MHz LRDIMM M386A4G40DM0-CPB | Intel SSD DC S3500 240GB | Intel S1100ADU00 1100W 80Plus Platinum |
All tests were executed over a 10GbE connection.
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Black Obsidian - Tuesday, April 28, 2015 - link
I've always hoped for more in-depth coverage of the OpenCompute initiative, and this article is absolutely fantastic. It's great to see a company like Facebook innovating and contributing to the standard just as much as (if not more than) the traditional hardware OEMs.ats - Tuesday, April 28, 2015 - link
You missed the best part of the MS OCS v2 in your description: support for up to 8 M.2 x4 PCIe 3.0 drives!nmm - Tuesday, April 28, 2015 - link
I have always wondered why they bother with a bunch of little PSU's within each system or rack to convert AC power to DC. Wouldn't it make more sense to just provide DC power to the entire room/facility, then use less expensive hardware with no inverter to convert it to the needed voltages near each device? This type of configuration would get along better with battery backups as well, allowing systems to run much longer on battery by avoiding the double conversion between the battery and server.extide - Tuesday, April 28, 2015 - link
The problem with doing a datacenter wide power distribution is that at only 12v, to power hundreds of servers you would need to provide thousands of amps, and it is essentially impossible to do that efficiently. Basicaly the way FB is doing it, is the way to go -- you keep the 12v current to reasonable levels and only have to pass that high current a reasonable distance. Remember 6KW at 12v is already 500A !! And thats just for HALF of a rack.tspacie - Tuesday, April 28, 2015 - link
Telcos have done this at -48VDC for a while. I wonder did data center power consumption get too high to support this, or maybe just the big data centers don't have the same continuous up time requirements ?Anyway, love the article.
Notmyusualid - Wednesday, April 29, 2015 - link
Indeed.In the submarine cable industry (your internet backbone), ALL our equipment is -48v DC. Even down to routers / switches (which are fitted with DC power modules, rather than your normal 100 - 250v AC units one expects to see).
Only the management servers run from AC power (not my decision), and the converters that charge the DC plant.
But 'extide' has a valid point - the lower voltage and higher currents require huge cabling. Once a electrical contractor dropped a piece of metal conduit from high over the copper 'bus bars' in the DC plant. Need I describe the fireworks that resulted?
toyotabedzrock - Wednesday, April 29, 2015 - link
48 v allows 4 times the power at a given amperage.12vdc doesn't like to travel far and at the needed amperage would require too much expensive copper.
I think a pair of square wave pulsed DC at higher voltage could allow them to just use a transformer and some capacitors for the power supply shelf. The pulses would have to be directly opposing each other.
Jaybus - Tuesday, April 28, 2015 - link
That depends. The low voltage DC requires a high current, and so correspondingly high line loss. Line loss is proportional to the square of the current, so the 5V "rail" will have more than 4x the line loss of the 12V "rail", and the 3.3V rail will be high current and so high line loss. It is probably NOT more efficient than a modern PS. But what it does do is move the heat generating conversion process outside of the chassis, and more importantly, frees up considerable space inside the chassis.Menno vl - Wednesday, April 29, 2015 - link
There is already a lot of things going on in this direction. See http://www.emergealliance.org/and especially their 380V DC white paper.
Going DC all the way, but at a higher voltage to keep the demand for cables reasonable. Switching 48VDC to 12VDC or whatever you need requires very similar technology as switching 380VDC to 12VDC. Of-course the safety hazards are different and it is similar when compared to mixing AC and DC which is a LOT of trouble.
Casper42 - Monday, May 4, 2015 - link
Indeed, HP already makes 277VAC and 380VDC Power Supplies for both the Blades and Rackmounts.277VAC is apparently what you get when you split 480vAC 3phase into individual phases..