raspberry pi feasibility

[rustysocket]

So I heard raspberry pi's can be linked together and pool their computing power. At around $35 each would it be cheaper to buy a bunch of raspberry pi's instead of a pc?

[razark]

Depends on what a "bunch" is.  You could get (Price of PC)/35 Raspberry Pis for the same price.  So, if you get ((Price of PC)/35)-1 Raspberry Pis, it will be cheaper.

[Guest]

No.  The Pi can be linked together in a network, to make it faster than the single one, but it really can't do a lot more than that.  It really doesn't have any GPU, and 35 dollars gets expensive when you multiply that even by 12.  It is only meant for small projects, or teaching about computers, which it its real goal.  Yes, you can do a lot with it, but you'll spend a lot more money making a Pi cluster computer than just buying, or building, a computer.  Secondly, Raspberry Pi's only have SD ports.  SD cards have a limited amount of writes to them, meaning after you write, or modify any files in any way, you're a bit closer to its death.  I can't remember off of the top of my head, but with most modern day OS's, you'd probably only last a couple year.  Also, most of the time, this power can only be used with the terminal via SSH.  Yes, you can pool computing power, but it's mainly just running one process on one, another on another, and so on.  So, again, no.

5 minutes ago, razark said:

Depends on what a "bunch" is.  You could get (Price of PC)/35 Raspberry Pis for the same price.  So, if you get ((Price of PC)/35)-1 Raspberry Pis, it will be cheaper.

But, we're also looking at cost effectiveness.  If I want to make a Pi cluster computer out of 20, then it will cost $700.  You can get much more out of another computer for $700.  Also, where did that equation come from?

Yes, it would be cheaper price-wise, but it would also be cheaper in quality, and would barely run KSP. 

[dr_jt]

Yes they can.

Good luck on getting KSP running on it. Applications have to written specifically to run on the computer and depending on how they are written they can still get CPU bound.

 

http://www.zdnet.com/article/build-your-own-supercomputer-out-of-raspberry-pi-boards/

[razark]

31 minutes ago, CliftonM said:

But, we're also looking at cost effectiveness.  If I want to make a Pi cluster computer out of 20, then it will cost $700.  You can get much more out of another computer for $700.  Also, where did that equation come from?

Yes, it would be cheaper price-wise, but it would also be cheaper in quality, and would barely run KSP. 

Nobody mentioned effectiveness.  Only cost.

 

But aside from the cost, it's also probably not worth the effort to try and set up a Pi supercomputer and write the software to do any useful task.

[stibbons]

A Raspberry Pi cluster won't be a reasonable replacement for a PC for general purpose computing. But if you're at all interested in learning how distributed computing works, you can run up a small Hadoop cluster using Pis very cheaply.

[Shpaget]

4 hours ago, razark said:

Nobody mentioned effectiveness.  Only cost.

Then why bother with multiple Pis? One Pi will always be cheaper than any desktop PC.

Also, the price has gone down a bit:

https://www.raspberrypi.org/blog/raspberry-pi-zero/

[Albert VDS]

The Raspberry Pi is actually a good desktop computer for basic internet browsing(no flash or heavy HTML5), e-mail and office applications.
It can also be used as a media center or play old games(for example via DosBox).

[Nuke]

ive seen a lot of parallel computing done with raspberry pis. beowulf clusters with many nodes like this 33 node setup. i guess its ok if you want to do parallel computing on the cheap. sort of a way for hardware people to get a cheap intro to supercomputing. software people would just use their gpus and ee types their fpgas to learn about writing code for and designing supercomputer systems. so there is more than one angle (the cheapest one being gpu based coding). 

what it wont do is make a replacement for your pc. whole different paradigm. software for one wouldn't work on the other unless it was specifically designed to.

ive mostly used my raspberry pi 2 for a makeshift diy tablet, which i never use because horrible battery life.

Edited January 20, 2016 by Nuke

[razark]

5 hours ago, Shpaget said:

Then why bother with multiple Pis? One Pi will always be cheaper than any desktop PC.

Because the original question was regarding whether a "bunch" of Pis was cheaper than a PC, not whether a single Pi was cheaper than a PC.

[Tex Mechs Robot]

12 hours ago, CliftonM said:

Also, where did that equation come from?

It was just a derived formula using algebraic principles. If we were only discussing the cost effectiveness and not the feasibility, that formula would answer the question. If the price of the PC in question were $700, then 700 divided by 35 gives 20. So it would take 20 Pi's to equal the cost of the one PC. Subtract 1 and you have 19 Pi's is cheaper than 1 PC.

[razark]

9 minutes ago, Tex Mechs Robot said:

It was just a derived formula using algebraic principles. If we were only discussing the cost effectiveness and not the feasibility, that formula would answer the question. If the price of the PC in question were $700, then 700 divided by 35 gives 20. So it would take 20 Pi's to equal the cost of the one PC. Subtract 1 and you have 19 Pi's is cheaper than 1 PC.

Thanks.  I completely missed that question.

[Shpaget]

4 hours ago, razark said:

Because the original question was regarding whether a "bunch" of Pis was cheaper than a PC, not whether a single Pi was cheaper than a PC.

Which would logically mean "any number of RPis necessary to achieve the same performance as a single desktop PC". Otherwise the question would make absolutely no sense, considering that any other quantity that fits the description of "a bunch of" could be either cheaper or many times more expensive than a PC.

[razark]

Hence me opening with "Depends on what a 'bunch' is."

While it could be inferred that is what the question meant, it does not logically follow that that is necessarily what the question meant.  Perhaps the original poster was interested in clustered computing, and wished to know whether it would be more expensive to set up a number of virtual machines on one PC to simulate it vs. setting up a number of Pis.

[Nibb31]

The limitation is going to be communication between each Raspberry Pi. They are limited by design to a crappy 100Mbps bus that shares USB and Ethernet connections, so even if you cluster 1000 Pis together, you will never get the performance of a modern PC. The bus bandwidth is going to be the bottleneck, and the more Raspberries you add to the cluster, the worse it's going to get.

The Pi cluster idea is a fantastic educational project for computer science students who want to study parallel processing without using valuable time on a real super computer, but it isn't worthwhile if you are after actual processing power.

Edited January 20, 2016 by Nibb31

[Nuke]

im still waiting for a pi zero array. i suppose thats difficult due to the lack of ethernet, but surely you can use the gpio as a parallel bus. im also disapointed not to see a compute module backplane pop up.

[magnemoe]

10 hours ago, Shpaget said:

Which would logically mean "any number of RPis necessary to achieve the same performance as a single desktop PC". Otherwise the question would make absolutely no sense, considering that any other quantity that fits the description of "a bunch of" could be either cheaper or many times more expensive than a PC.

And it would not, the only software who is designed to run load balanced on multiple computers are very heavy calculations from render farming who might be interesting for some of us, cloud application servers up to supercomputers. Other programs is designed to run on single computers. 
Yes an stack of pi might be nice to learn and test this sort of programs. Else its like buying 10 scooters instead of an car

 

 

[Nuke]

On 1/21/2016 at 5:32 PM, Nuke said:

im still waiting for a pi zero array.

i guess i spoke too soon. here is a backplane for a 16 node pi zero array. it was only a matter of time.

Edited January 26, 2016 by Nuke