Dioxin
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Tue Jan 03, 2012 3:00 pm

when I get time I'll try to get a scores for an i5 2500 for you. (mini-itx board, with 8Gbs RAM) approximate cost £265 when I bought it.

I think for the most part, the R-Pi provides a cost effective solution to have a real hardware cluster cheaply, power per/whatever will almost always be beaten by an alternative.

mightygoose
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Tue Jan 03, 2012 7:21 pm

[linkie]

would that be a suitable powered USB hub for a modest Bramble?

Svartalf
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Tue Jan 03, 2012 8:31 pm

mightygoose said:


[linkie]

would that be a suitable powered USB hub for a modest Bramble?



Very probably.  I was contemplating something much like that for this.  Only drawback is going to be that each port's clearly going to source 500mA, period.  Doesn't leave a lot of room for tacking things off the R-Pi's in the cluster.  You'll certainly won't be powering a USB HD unless it's one of those Matsunichi drives MicroCenter was flogging in the stores (store sales only...sigh...) off of the master with that.  Best you could hope for there is probably scoring a 16-32Gb class 4/6/10 SD card for the master for the cluster.

Svartalf
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Tue Jan 03, 2012 8:39 pm

Dioxin said:


when I get time I'll try to get a scores for an i5 2500 for you. (mini-itx board, with 8Gbs RAM) approximate cost £265 when I bought it.

I think for the most part, the R-Pi provides a cost effective solution to have a real hardware cluster cheaply, power per/whatever will almost always be beaten by an alternative.


Heh...  No comparison in the case of the i5 boards.  They'd paste a PandaBoard or modern Atom cluster...and HARD.  Only drawback there is the heat.  The cluster would be a pricey space heater that could be hammered by a top-end i7 based system design (Which, since it's insane expensive, you'd be fielding 10G or faster interconnects between nodes and high-end GPGPU cards in it all...which would pretty much leave everything else behind in it's dust...)

As for your supposition, you'd be right.  Main goal with a Bramble is to teach people how to make a marginally effective HA/HPC cluster on the cheap so you can teach that direction of thought.

You can do anything you set your mind to- but some things require you to teach people how to make their minds move in the right ways to do them.  Some things currently require fairly expensive hardware (even the Mini-ITX stuff's pricey compared to a Bramble's base components...) to show people how to do this stuff.

hamjudo
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Tue Jan 03, 2012 9:19 pm

Dedicated R-Pi clusters are expensive. Temporary R-Pi clusters will be available cheaply for anyone is buying R-Pi's for their students, and class hasn't started yet. For example, Dr. George teaches summer camps (currently with Lego Mindstorms, or Arduinos, but the R-Pi is a logical next step), usually with 16 or so students per session. Since he needs systems for the instructor, and some spares, he usually gets on the order of 20 of each system. Each camp lasts a week.

In that environment, the cost to make a temporary 20 node R-Pi bramble is just the time it takes to put it together. He won't need to configure a special power supply, since he has power supplies for every node already. I have seen his bin of power strips. It is ugly, but he can plug in 20 wall warts. He already has ethernet switches.

This kind of cluster isn't available for weeks at a time, while he is busy teaching students, but the cost is great.

I would imagine that many teachers will be in a similar position. When class isn't in session, they can use a classroom full of Raspberry Pis for something else. That something else can be a bramble.

mightygoose
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Tue Jan 03, 2012 9:22 pm

Svartalf said:


mightygoose said:


[linkie]

would that be a suitable powered USB hub for a modest Bramble?


Very probably.  I was contemplating something much like that for this.  Only drawback is going to be that each port's clearly going to source 500mA, period.  Doesn't leave a lot of room for tacking things off the R-Pi's in the cluster.  You'll certainly won't be powering a USB HD unless it's one of those Matsunichi drives MicroCenter was flogging in the stores (store sales only...sigh...) off of the master with that.  Best you could hope for there is probably scoring a 16-32Gb class 4/6/10 SD card for the master for the cluster.


Actually i figured i would use the 7 way to power a 4-6 raspi cluster with the 7th outlet powering an external HDD (dual usb inputs power/data are not uncommon) and let its USB connect to the central node. I always figured that running the other nodes in parallel off of the central node would be easier than a swarm to both construct and program.

As to the card issue I just picked up one of these as par for the course for my Desire HD.

[linkie]

The class 10 16GB cards are only 17.99 atm, and all come with SD card adapter. Seem to be fairly cheap while maintaining reliability.

[linkie]

rasppi
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Thu Jan 19, 2012 1:56 pm

this might help some of you it might not, im designing a case/with a card/slot load feature for deployment of more than one RPI, was for a completely separate Idea but does look like it can be used for bramble Idea, rackmount size(near enough) 5 slots and the 6th slot at end when i can find some dimensions ill design for a built in switch.

so 5 PI's in 1 "19 rack case with built in switch sounds ideal for the bramble.

just got to work out how to make the case was thinking 3d printing but think it might be a bit complex unless I broke it down.

Each card will have a camlock to stop it sliding out, and prying hands from stealing your hardware (havnt got this far in the design bit yet, designed so you still have access to all connectors (admittedly using some 90 degree bends)




mightygoose
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Thu Jan 19, 2012 2:24 pm

@rasppi, while i like the idea, what network topology would you be using?

Matthew Jones
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Thu Jan 19, 2012 5:12 pm


mightygoose said:


[linkie]

would that be a suitable powered USB hub for a modest Bramble?


No It wouldn't, the Hub is fine, the power supply is not. its rated at 5v 1A. each RasPi pulls 500 -700mW. So 2 Pi's would over stretch the power supply let alone 7 of the critters


rasppi
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Thu Jan 19, 2012 8:33 pm


@mightygoose - didn't really plan that far? originally i designed it for another project

this could also be used in education (cam lock prevents thefts) and ability to rack it suits many ICT managers. 2 cents.


Skree
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Mon Feb 06, 2012 9:14 am

i'm completely new to the concept of clustering computers - i've heard of it, but never seen it in the flesh or done it... but my interest in the Pi has caused me to be curious about it... so i have a (probably silly) question..

Could clustering be used in a similar sort of way to how multicore processors work - IE, connect one or more Pis together to make them a bit more meaty when working in a linux type environment? for example, I want to try and use a Pi to for most of my day-to-day computing. It would be good if i could connect say 2 Pis together to be able to do more stuff at once, and perhaps without lag - multiple tab browsing, having media players open, document readers, etc. I'm thinking it would be useful to have potentially two usb bus' to work with

i'm mentally picturing a pc made by stacking Pis together using motherboard type standoffs then encasing the whole thing in glass or acrylic

(ooh, thekthy) hehe

kme
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Mon Feb 06, 2012 9:47 am

Skree said:

Could clustering be used in a similar sort of way to how multicore processors work - IE, connect one or more Pis together to make them a bit more meaty when working in a linux type environment? for example, I want to try and use a Pi to for most of my day-to-day computing. It would be good if i could connect say 2 Pis together to be able to do more stuff at once, and perhaps without lag - multiple tab browsing, having media players open, document readers, etc. I'm thinking it would be useful to have potentially two usb bus' to work with
In theory this is doable and will be an eyeopener, but as a practical tool R-Pi is useless as a cluster computer. The bottleneck for all clusters is the inter-CPU connection and with only a USB2 bus available R-Pi is completely hopeless. Even 10 Gb/s is a bottleneck.

If you want power buy x86. However, if you want to learn this project absolutely feasible. Go have a look at the Mosix kernel, that automatically distributes jobs among CPUs on separate computers.

mole125
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Mon Feb 06, 2012 10:46 am

kme said:


In theory this is doable and will be an eyeopener, but as a practical tool R-Pi is useless as a cluster computer. The bottleneck for all clusters is the inter-CPU connection and with only a USB2 bus available R-Pi is completely hopeless. Even 10 Gb/s is a bottleneck.

If you want power buy x86. However, if you want to learn this project absolutely feasible. Go have a look at the Mosix kernel, that automatically distributes jobs among CPUs on separate computers.


Not strictly accurate, there's also the network link, GPIO ports and if someone were really creative (and desperate) they could try and hack the GPU interface to transmit data through the input and outputs they provide. I'd agree with your conclusions though that not of these are going to get you particularly good transfer speed which limits what types of distributed problems you can usefully do - but not all problems necessarily need large amounts of data transfer to be affective - look at teh SETI at Home and similar cluster projects where the data distribution method was a dialup modem link!

MikeM
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Mon Feb 06, 2012 8:30 pm

Hi Folk , I've just joined the Rapsberry Pi Forums  and so excited  that there is a Bramble forum!!

Back in my Uni days around about the time the world was about to end because of Y2K , me and a few buddies built a beowulf cluster using the 32 PC's in our student  Elec Eng computer lab network using mosix. The hardware was quite rubbish (even back then ) but we still managed to squeeze some awesome processing power it using Povray renderer as a benchmark tool.

Once I left Uni I have been in embedded development for most of my career and have always wanted to build a cluster from embedded processors.Which is why I am excited about bramble.

Apart form the educational value I do believe that bramble could be quite effective( assuming we can harness the GPU ) Consider this in 2007(just 5 years ago) a cluster called Microwulf cost $2500 and had an output of 26 GFlops. The gpu on the Raspberry Pi is capable of 24 GFlops on its own. What a great place to start!

Whilst the bramble might not be able to take on the Nvidia Tesla and Fermis of this world i.t.o FLOPS , I still reckon(as a thumbsuck) we could get a respectable FLOP/$ ratio and run it at a fraction of the power needed to run a conventional cluster.

The key issue I think  will be balancing the latency of the load  on the bramble network, and how much of the GPU we can harness...

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Lob0426
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Tue Feb 07, 2012 4:54 am

Though I believe a BRAMBLE will find useful work to do, I believe it will be mostly a learning tool in laying out a Cluster. The network speed is going to be the limit in this setup. The USB 2.0, which is where the network is based, is not going to reach anywhere near the 60 MBs that USB 2.0 is capable of. Having said this I believe a more useful solution for using RasPii in multiples will be as a distributed computing array. Each RasPi being given a specific task with the master displaying the results from all of the other RasPii.
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mikefife
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Tue Feb 07, 2012 12:44 pm

liz said:


I love the idea of calling a cluster a Bramble. Consider the term as having official Raspberry Pi blessing!



A cluster should be a 'Bramble Patch' surely

labrat
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Wed Feb 08, 2012 6:25 pm

I've been attempting to skim through all of the Bramble related threads in search of an answer, but I've not had much luck. I'm interested in the concept for number-crunching using R, nothing too complex. What I would like to know, if possible, is roughly how relative the performance of a RasPi cluster would scale relative to a desktop PC. I'm not looking for response indicating what it is not - e.g. "a Bramble is no i5-xxxx"; but a response indicating what it may potentially be "8xRasPi in a cluster is comparable too...< P4-800MHz or whatever>".

Any takers?

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Gert van Loo
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Wed Feb 08, 2012 7:05 pm

I have posted this before. Although I am a Raspberry-Pi fan (and designer) I do not think the board is the best choice for cluster building. Raspberry-Pi gives you the highest mips/watt but not the highest mips/dollar. So for real performance I would look elsewhere.

Shorack
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Wed Feb 08, 2012 7:26 pm

Gert said:


I have posted this before. Although I am a Raspberry-Pi fan (and designer) I do not think the board is the best choice for cluster building. Raspberry-Pi gives you the highest mips/watt but not the highest mips/dollar. So for real performance I would look elsewhere.


What about lifetime cost then? (so taking into account electricity costs as well as hardware costs)

And is that assuming the gpu can be put to work in some way?

Trying to sound curious instead of desperate, not sure if it's working. :p

pjt
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Wed Feb 08, 2012 7:46 pm

I have picked these figures off the web, so no guarantees!

If you can program the GPU as well as the processor (and can utilise the parallel processing) then you need 5 R-pi to match a core-i7

But if you just use the processor then you will need a few hundred.

linorics
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Sun Feb 12, 2012 7:07 pm

Joined to add a comment

In regards to the power. Could I use the 5v on a plan mini ITX PSW.

http://www.newegg.com/Product/.....6817104080

I have little electronic experience so please let me know if this wouldn't work.

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abishur
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Mon Feb 13, 2012 3:42 am

linorics said:


Joined to add a comment

In regards to the power. Could I use the 5v on a plan mini ITX PSW.

http://www.newegg.com/Product/.....6817104080

I have little electronic experience so please let me know if this wouldn't work.



Sure in theory   The only thing to keep in mind is that you'll need to jumper some pins so it will actually turn on and send power.
Dear forum: Play nice ;-)

summers
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Mon Feb 13, 2012 9:21 am

linorics said:


Joined to add a comment

In regards to the power. Could I use the 5v on a plan mini ITX PSW.

http://www.newegg.com/Product/.....6817104080

I have little electronic experience so please let me know if this wouldn't work.



If going that way wouldn't it be easier to use a smaller switched mode PSU, such as:

http://uk.mouser.com/ProductDe.....Puvw%3d%3d

Shorack
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Mon Feb 13, 2012 1:10 pm

Wouldn't it be the most efficient to have a decent powered USB-hub to power a bramble?

Unrelated (to powering them), are there people who want to seriously try to put life into a bramble, trying to get the most out of it?

There are a few algorithms who are easily to paralleled and who could be made a bit more flexible to cope with connection limitations (e.g. throughput over the network)

I'm mainly thinking at random forests and ant colony algorithms right now.

If the necessary expertise could be brought together to tackle the following elements, it could at least get to a somewhat useful level:


- GPGPU (from what i read in svartalf's posts, should be doable be it in an indirect way)
- stripped down OS
- establishing lightweight communications between nodes
- balancing parameters to adapt to loads*
- giving the algorithms some more flexibility*
- project management with a stick and a carrot (else nothing gets done)

Got to amit, mostly relies on the first point. No decent usage of the gpu = no performance

* to give an example: if the tcp/ip gets overloaded by the data transfers, you could make a random forest algorithm adapt by running more trees on a single sample set or an adapt ant colony by letting more ants run before passing the update of pheromone weights to other nodes.

Fafler
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Mon Feb 13, 2012 4:15 pm

What about Bitcoin mining? I don't think at has been discussed before, but a central concept in Bitmining is machines collaborating in mining pools. The network requirements are low as each client downloads a chunk of data and work on it for some time, the same way as [email protected], compared to applications where clients need to exchange data near-realtime.

You are paid by the Bitcoin network itself for mining coins, and it actually seems some people are able to earn back the price of expensive ATI GPU's by using them for mining.

If the Rasberry in any way has the raw CPU power to compete with GPU's, or even better, if becomes possible to do GPGPU on the Rasberry GPU at some point, it could be really interesting to pay the cost of a Bramble by mining.

ARM benchmarks are here: https://en.bitcoin.it/wiki/Mining_hardw ... arison#ARM

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