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bazza14
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Tue Feb 14, 2012 8:01 am

tachyon said:


Well, I know I"m buying at least 4-6 to learn, and then teach clustering to my kids. Should be fun! Any thoughts on management? Is something like Oscar or Rocks looking like a fit for the noob like me. From my research tonight, I think Oscar will work.

*quick edit*

I"m not an electrical engineer, but there"s got to be a way to combine power supplies, to get a one wall wart to many r-pi"s powered? That my next research path. It can"t be as easy as getting a small pc power supply and splicing out the 12vs

*quick edit 2*

The power supply thing was bugging me before bed, I think the medical device industry has us covered. Could someone smarter than I look at these: http://www.trcelectronics.com/.....ulti.shtml and see if they got the juice to power our berries? Goodnight!


These require 5v and 700ma each so if you want a cluster of 16 you would need a supply capable of delivering a min of 11.2 amps @ 5V it does not matter how it's derived as long as the regulation is good and ripple free. Always good to go maybe 20% higher so it's not cooking so 13 amps would be cool. So could be a PC power supply, a lab bench PSU or a car battery with a 5v regulator hanging of it.
LINUX convert since 2003

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

Fri Feb 17, 2012 9:08 am

The whole thing could fit in a suit case, with a suitcase with a battery pack for UPS functionality.

You need the following:


A bunch of RPIs.
A suitcase. Preferably aluminium or titanium, so it's robust, and doesn't lose integrity when making holes and stuff.
An appropriate number of big battery packs with as many USB power outs as possible. This will provide UPS functionality.
An appropriate number of USB power splitters
An appropriate number of switches running on USB power
Cables (Ethernet and USB)

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

Fri Feb 17, 2012 3:14 pm

BTW: Each board should be referred to as a Berry. Then a cluster of these would be a Pie

d7p
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Sat Feb 18, 2012 9:38 pm

Has anyone thought about Hadoop it would make this a bit easier although I don"t believe you can use the gpu

Sins this is now been used in many coprorations it would be good to learn, hence why I wish to use it.

Another gd point about using Hadoop is the hdfs file system not needing one big drive so each berry in the bush could have extra in the SD card ( so 2gb for the operating system and then 2gb for the hdfs, make the drive size equal to number of berries x2gb)

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

Sun Feb 19, 2012 7:40 pm

Has anyone thought about Hadoop it would make this a bit easier although I don"t believe you can use the gpu

Sins this is now been used in many coprorations it would be good to learn, hence why I wish to use it.

Another gd point about using Hadoop is the hdfs file system not needing one big drive so each berry in the bush could have extra in the SD card ( so 2gb for the operating system and then 2gb for the hdfs, make the drive size equal to number of berries x2gb)

Finally someone is talking software here. While it may sound tempting to develop your own cluster management framework, I think it is a very complex thing to do and it requires detailed knowledge of the topic. I just had a quick look at the Hadoop website and it sounds like a good foundation for the Bramble project.


d7p
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Sun Feb 19, 2012 10:13 pm

The inishal set up is well documented as well, and there are several books on Hadoop in the amazon collection. witch is why it is my choice when I can get a couple of berries.

Cassandra (facebook"s database)+Hadoop is probably what I will go with as this gives a NOSQL database with in the cluster that can be queried ( not quite in the same manner as standard SQL but close) and the hadoop engin for anilitical analysis of the data to give charts, graphs, maps, trends, and so on as far as you can think. The are several other combinations of DB and Hadoop but this seams to a more mature combination.

This would scale quickly and allow the berries to be used for other teaching applications, as it runs as a possess in the JVM ( java virtual machine) on any flavour that you can install java on.

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

Sun Feb 19, 2012 10:52 pm

This would scale quickly and allow the berries to be used for other teaching applications, as it runs as a possess in the JVM ( java virtual machine) on any flavour that you can install java on.

As long as no technical restrictions (i.e. the Rpi"s limited memory) make it impossible to use Hadoop as it uses Java. But I like that Java approach of the project, which may be easier for beginners to get familliar with than, say C or C++. SLURM also looks quite interesting, and one can always follow the well-known beowolf howto if anything else fails. A friend of mine had this idea of a Rpi cluster to run multiple "povray" 3D renderers.

d7p
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Sun Feb 19, 2012 11:11 pm

It looks to me as if java should run fine on the rasberrypi as the requirements say 64Mb of ram.
http://www.java.com/en/downloa.....sysreq.xml

That should be possible with out Hadoop or any cluster software if he can separate out the work. I have only played with povRay at uni so don"t know much about it"s inner workings.

SLURM seems a good alternative but wouldn"t allow the nodes to be used for other tasks. And sins this wold be a teaching toy for many, the ability to still have a usable Linux distor with GUI and other programs would be appealing.

Edit: after looking more closely at SLURM you could use the nodes for other things, from what I read inishaly I thought it was a full distro. You could use both, having SLURM as the manager and hadoop as the slave. SLURM lacks the DFS (distributed file system) that Hadoop has in hdfs so you would need a central/large HDD connected to one of your nodes to serve the data. Unless I have missed something else.

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

Mon Feb 20, 2012 9:15 am

What you mention are the requirements just for the java vm. (well, i presume it's that since it is a link to the java site) So you need to take into account extra memory to just run hadoop on the nodes. And then you still need some to start doing stuff with it.

My experience with java-based applications (both spare-time use as well as business applications) is that they are a huge draw on your memory. And when you only have 256mb, you want to really be paying attention to it.

So if you are just interested in setting something like that up, i suppose it is fine. But if you actually want to put it to use, i would be wary of hadoop.

ps: It may of course be that i'm working with crappy software.

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

Mon Feb 20, 2012 1:41 pm

I was not directly planning on clustering as my first RPi project, but I will leave a remark on java here for you: java is extremely widespread on embedded devices, and there are minimalistic versions specificly for this purpose: http://www.oracle.com/technetw.....index.html

There are basicly two versions:

- Java SE, which is the standard runtime but optimzed for mid-range to high-end embedded systems. This will run on devices starting with 32Mb memory.

- Java ME, which is the java MicroEdition and this one is based on the Connected Device Configuration, which is a subset of the java standard. This will run from as little as 8Mb, but (probably) won't do Hadoop. The CDC spec was used for older mobile phones which could run java applications, from the age before the i/smart-phones (I've had some fun with it).

I'm fairly certain the normal Java SE for embedded will run perfectly fine Don't know about the requirements for Hadoop though, I've never used it.

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

Mon Feb 20, 2012 2:09 pm

d7p said:


That should be possible with out Hadoop or any cluster software if he can separate out the work. I have only played with povRay at uni so don"t know much about it"s inner workings.


There are special versions of povray that are either patched to work with the MPI (message passing interface) or PVM (parallel virtual machine) libraries. The advantage of these patched versions is that they are enabled for real distributed computing utilizing special libraries und fuctions.

However, there also is a solution that uses the stock version of povray as there is a special script which creates "tiles" of the complete scene to be rendered and manages which node in the cluster has to render which tile.

You can even have a renderfarm based on the "blender 3D" graphics suite. There's a nice article about how to set up such a thing on the web.

But if you want your very own application to be ready for distirbuted computing (i.e. you have written code to generate a mandelbrot fractal), you probably will have to use MPI or PVM or any other framework that takes care of the distribution of your calculations.

S0litaire
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Mon Feb 20, 2012 2:30 pm

Ahh!!! this takes me back to my college days.

My HND in Computing Project the group i was in used PovRay with Linux / Beowulf cluster of 12 Intel P2's to render images.

Called "The Drinks Machine" each PC was named after a canned drink (Might still have the files and source code in a box somewhere!!) lol
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MegaGumbo
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Mon Feb 20, 2012 2:55 pm

S0litaire said:


Ahh!!! this takes me back to my college days.

My HND in Computing Project the group i was in used PovRay with Linux / Beowulf cluster of 12 Intel P2's to render images.

Called "The Drinks Machine" each PC was named after a canned drink (Might still have the files and source code in a box somewhere!!) lol



It's not a too complex thing to set up and meanwhile you learn the very basics about farm clustering. Also, in the end you get a visual result (the rendered image) to show to people. If we're talking about learning and understanding, something like this is important for motivation.

d7p
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Mon Feb 20, 2012 5:40 pm

S0litaire said:


If we"re talking about learning and understanding, something like this is important for motivation.


Being able to see the results so easily would be good.

The map/reduce function in Hadoop could also help with the ram issue
If each map is short/ not to memory exustive then using the java SE (smeaggie serggested) sounds good to me.

CompGeek812
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Tue Feb 21, 2012 9:17 pm

I'm planning to try to run a small Hadoop cluster though have concerns about ram.

Hadoop defaults to 1GB of ram per daemon, so a minimum of 2GB per node plus 200MB per child jvm (map/reduce tasks).

I've tried lowering the ram available which typically causes Hadoop to hang on simple jobs and then crash.

Gonna have to dig around in the config files and see how small I can make it run reliably, any suggestions?

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

Wed Mar 07, 2012 10:07 am

I already have some access to a "Condor" cluster, so it should be very simple to test a reaspberry as a clint and see how it compares to a standard desktop.

I am sure it wont be as fast, but will be fun to try and for cost and power it may well win out over a desktop.

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

Wed Mar 07, 2012 5:12 pm

Just adding my interest... I would definitely like to build one of these

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

Wed Mar 07, 2012 6:58 pm

Just adding interest too.

Useless piece of information ... I believe raspberries are known as 'cluster fruits' (along with blackberries) owing to the fact that they are a cluster of individual fruits (each little ball has a single seed inside).

Probably just as useless a thought...

Is there any way with CAT-5 of splitting the TX and RX lines and sending them to different computers?  I am thinking you could form a kind of ring (so TX goes to the clockwise, RX comes from the anticlockwise), I am guessing it would need a different protocol (or at least a modified form of ehternet) so that any node that receives a packet not for itself sends it on rather than ignoring it.

d7p
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Re: Cluster (Bramble...) Design Discussion (Advanced)

Wed Mar 07, 2012 7:21 pm

You are describing a ring network tapology. I don"t know if you can split the Ethernet cable and still have it work.

However this would give you a low through put network. Sins each berry touches the packet and so processes it.

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

Wed Mar 07, 2012 8:16 pm

truan said:

Probably just as useless a thought...
Is there any way with CAT-5 of splitting the TX and RX lines and sending them to different computers?  I am thinking you could form a kind of ring (so TX goes to the clockwise, RX comes from the anticlockwise), I am guessing it would need a different protocol (or at least a modified form of ehternet) so that any node that receives a packet not for itself sends it on rather than ignoring it.



Basically, that's what a hub does.  All computers get all data and ignore anything not for them.
Dear forum: Play nice ;-)

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

Wed Mar 07, 2012 9:09 pm

Abishur said:


truan said:


Probably just as useless a thought...
Is there any way with CAT-5 of splitting the TX and RX lines and sending them to different computers?  I am thinking you could form a kind of ring (so TX goes to the clockwise, RX comes from the anticlockwise), I am guessing it would need a different protocol (or at least a modified form of ehternet) so that any node that receives a packet not for itself sends it on rather than ignoring it.


Basically, that's what a hub does.  All computers get all data and ignore anything not for them.


You are indeed correct, but didn't we all stop using them in favour of switches as switches were more efficient?!  ;)

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

Wed Mar 07, 2012 9:17 pm

spurious said:


Abishur said:


truan said:


Probably just as useless a thought...
Is there any way with CAT-5 of splitting the TX and RX lines and sending them to different computers?  I am thinking you could form a kind of ring (so TX goes to the clockwise, RX comes from the anticlockwise), I am guessing it would need a different protocol (or at least a modified form of ehternet) so that any node that receives a packet not for itself sends it on rather than ignoring it.


Basically, that's what a hub does.  All computers get all data and ignore anything not for them.


You are indeed correct, but didn't we all stop using them in favour of switches as switches were more efficient?!  ;)



Indeed, but that's what he described... well to be more technical he described a token ring network and not just a network in a ring topology, but with how cheap switches are these days you would be a lot better off just getting a plain jane switch and being done with it
Dear forum: Play nice ;-)

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

Thu Mar 08, 2012 8:46 am

OK, just to clarify, yes I know it's a ring network (I was actually thinking more like Real Time Token Ring), what I was wondering is whether the data link layer would 'allow' it, or whether you would need to rewrite stuff and the lower network layers (which I am thinking are possibly 'hard coded'.

I realise switches are cheap, but its another component – fair point about the low capacity, but if the only data is control messages (and the actual data is shared by using some kind of shared drive connected up to the sd card slots….)

To be honest, I was more just curious whether it could work – is it even possible to rewrite the parts you would need to on the Pi?

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

Thu Mar 08, 2012 9:57 am

My gut instinct is that the ethernet chip is designed for ethernet and would probably be next to impossible to force it to do other stuff.

You could probably achieve what you want for short distances using the GPIO pins, in pariicular the I2C and/or SPI interface. With I2C it should be the case of connect them all on the wire possibly with a few resistors. However you would only be able to get 100kbit/s or so transfer rate like this so while possible it really isn't a sensible solution. It's also a bus not a token ring but you could make it token ring if you alternated between I2C and SPI between each pair.  Or if all you care about is low speed control messages then bit banging the GPIO ports yourself would allow any topography you wanted.

Of course as you know you can buy 5 port switches for < £10 and 16 port ones for < £20 so it really depends how much your time and curiosity is worth

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