Raspberry Pi server clusters

pcworld.com wrote:

 

 

The Boston Viridis server has up to 48 Calxeda chips -- 192 ARM cores in a 2U enclosure -- with integrated networking and storage units. Each Calxeda chip consumes as little as 5 watts per chip, U.K.-based Boston said in a statement.

Interesting, for the server farm, but I'd be happy with a much more down-to-earth 16 ARM cores of Cortex-A vintage in a 1U form factor, with gigabit Ethernet and SATA.  Pretty low spec really.

I'd be happy with a much more down-to-earth

It appears that at least the first generations are going to target datacenters, blades, and windows.

Microsoft mandating that 'secure boot' can't be disabled on Arm servers has already been widely reported elsewhere and could make it much more difficult to use alternative operating systems in the future.

Thankfully that doesn't appear to be the case with the Boston server as reported, hopefully they continue to produce systems along those lines.

Looking at it, there appears to be 12 processor cards in that system. Presuming it's modular enough, a single card would give you 16 cores and could be integrated into a smaller chassis ?

selsinork wrote:

 

Looking at it, there appears to be 12 processor cards in that system. Presuming it's modular enough, a single card would give you 16 cores and could be integrated into a smaller chassis ?

In principle, perhaps.  But in practice a company that is targetting data centers isn't likely to be interested in the other end of the market.  The breakthrough, if it happens, will come from an ARM licensee that isn't afraid to sell ARM application processors for $5 in volume, like TI did with the AM3358/9.

More news in this area:

• http://www.baserock.com/servers
• http://slashdot.org/topic/datacenter/low-power-slab-server-pairs-arm-with-linux/
• http://linux.slashdot.org/story/12/08/23/1512258/baserock-slab-server-pairs-high-density-arm-chips-with-linux

Summary quotes:

• "Each Slab CPU node consists of a Marvell quad-core 1.33-GHz Armada XP ARM chip, 2 GB of ECC RAM, a Cogent Computer Systems CSB1726 SoM, and a 30 GB solid-state drive"
• "32 cores into a half-depth 1U server".

I'm really surprised that there is so little of this kind of development going on.  It can barely be called a sector yet, few players and only background activity.  Is there even one such product on open sale from a large distributor?

Morgaine.

>I'm really surprised that there is so little of this kind of development going on.

I don't think the mips/$ or mips/watt work out too well yet compared to the i7.

In the rpi.org front page blog of 24 July 2012,

http://www.raspberrypi.org/archives/1655

Pete Stevens compares the RPi to the Mac Mini for web hosting:

"Is this sensible? We’ve had a few customers ask us if the Raspberry Pi would be a sensible device for hosting on as it’s very cheap and very low power. Unfortunately it’s also very slow for this kind of application and the supporting hardware is very bulky. The i7 quad core Mac Mini occupies less space than the Pi + hub + disk + PSU, uses about fives times as much electricity, costs about five times as much once you include the supporting hardware but is hundreds of times faster. So revolutionising the hosting industry isn’t going to happen with the Raspberry Pi, at least not until they build a PoE one with gigabit ethernet and more RAM."

That rpi.org quote is about the Pi though, a very old ARM machine which was never designed for CPU performance nor network throughput, nor even power efficiency for networking loads.  It can't be used as any kind of reference in the ARM server appliances field.

ARM plugtops have for some time now had gigabit networking and integrated disk controllers.  There's no huge reason why the same level of ARM technology couldn't be reworked into a 1U network appliance featuring a few of these SoCs interconnected by nothing more than a gigabit switch, for only a few hundred pounds BOM cost.  And higher models based on quad-core Cortex-A9 MPcore or Cortex-A15 too.

I bet there would be plenty of takers ... starting with me!

Morgaine.

the RPF is rumored to be planning to release benchmark results soon,

showing the RPi doing quite well against more modern ARM cpus.

Of course, comparing a single-core cpu to a multi-core is difficult.

The Cortex-A15 is yet to be seen, I believe.

coder27 wrote:

 

the RPF is rumored to be planning to release benchmark results soon,

showing the RPi doing quite well against more modern ARM cpus.

Of course, comparing a single-core cpu to a multi-core is difficult.

 

The Cortex-A15 is yet to be seen, I believe.

I would like to see independent benchmark results, so there's no conflict of interest.  But there's a general problem with benchmarks: how well is the benchmark going to predict any application other than the bechmark?  It's YMMV on steroids.

Just linking here for reference a list of basic design notes I made in another thread, as it's relevant to ARM clusters --- http://www.element14.com/community/message/61225#61225 .

Designing modules specifically for clustering is different to designing boards for standalone operation, as the operational requirements are really quite different.

What's more, the cluster design rules also apply if you're designing a standalone computer which happens to use a clustering architecture internally.  So, if you're making a standalone board containing multiple ARM processors, the design rules for clusters should be applied if you want an effective architecture, not the rules that you would use for a single-SoC board.

Just saw this at Geek Times: ARM, LSI on-chip link connects up to 32 cores

LSI Corp. and Calxeda Inc. are the first chip companies to license from ARM Holding plc a new on-chip interconnect developed for linking up to 32 cores on a die.  ARM's CoreLink CCN-504, delivering throughput in the range of 50-100 Gbits/s, will debut in LSI’s first ARM-based devices to be announced in February.