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Old 2006-12-27, 14:50   #1
fivemack
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I'm contemplating building a small compute farm - start with four nodes and work up.

Current thought for nodes is to use a 900-series dual-core P4 before they become completely unavailable, skimp on the motherboard, and go for a compact-flash-to-IDE adaptor for the operating system: say

D945 104.97
865G board 30.86
CF-to-IDE adaptor 15.00
boot flash 8.40 512MB
RAM 36.2 512M
case 25.43

= 220.86

Couple of questions: how easy is it to set up Linux on a compact-flash card? I guess I'd need a CF-to-IDE adaptor for my main machine and do a straightforward install from CD with the CF as target.

Is this a reasonable hardware spec, or is it more sensible to put on an E6300 low-end Core2 rather than the high-end dual-core Netburst? Five nodes of this would cost the same as a decent Kentsfield system; are ten Netburst cores competitive with the four Conroes?

mprime will run fine in 512M of RAM; does nfsnet? I appreciate 512M will be useless for lattice sieving.
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Old 2006-12-27, 19:40   #2
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You forgot the running costs in the whole equation. Electricity has an environmental and financial cost.

Another thing already stated in other threads : flash memory is not for ever. You would have to replace your flash disks quite often. I think a better solution would be to use second hand hard disks.
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Old 2006-12-27, 19:40   #3
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The QX6700 is in a rapid price decline, so if you have the option of waiting a couple of months, it will probably be significantly cheaper.
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Old 2006-12-28, 09:49   #4
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Quote:
Originally Posted by Jacob Visser View Post
I think a better solution would be to use second hand hard disks.
Undoubtedly the case. Small IDE disks (though still large in comparison with a 512M flash) can be picked up very cheaply indeed.

Tom: I know a couple of places in and around Cambridge where such disks can be picked up for a fiver or so. I'll contact you directly with more information if you're interested.

Paul
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Old 2006-12-28, 09:53   #5
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Quote:
Originally Posted by fivemack View Post
I'm contemplating building a small compute farm - start with four nodes and work up.

mprime will run fine in 512M of RAM; does nfsnet? I appreciate 512M will be useless for lattice sieving.
NFSNET should be fine on 512M machines. The sievers generally take between 50 and 200M, depending on how big a factorization is being done. Typical is 130M or so.

Something you may also wish to put into your farm is an ethernet switch with a reasonable number of ports. 2nd-hand 16-port switches are not too expensive. If you've a way of gluing your machines together, and enough permanent storage (another argument for disk rather than flash) you can make yourself a nice cluster.


Paul
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Old 2006-12-29, 17:31   #6
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or you could do a cheap proc like a AMD sempron 3000+ at 1.8 ghz
http://www.tigerdirect.com/applicati...227092&CatId=0
thats 9 dollars by the way

a cheap 939 mobo
a psu and a piece of wood


and then net boot the computers with a floppy drive to a os over the network using ltsp
ltsp.org
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Old 2006-12-30, 07:32   #7
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If your intended apps are math related, I would spend the extra on a Core2Duo rather than 9xx because of the better FP performance and improved power efficiency. The downside is it will cost you more for your motherboard, although that should make it more futureproof.

If virtualisation may be important to you in future make sure your chosen processor supports it.

I would say that a solid state boot will be quieter and use less power to run than a hard drive.

You probably don't have a lot of room on that size CF and recommend going for larger for both linux, your apps and data. Alternatively you could boot from a usb stick. Either way, you will need to select your OS distribution carefully and choose the particular things you need.

Don't write your logfiles to local disk, spool them across a network onto one real server with a real hard drive if you can.

Why bother spending money on cases? That is just cosmetics and will not help your processing. Just build some kind of box or rack to keep out dust and provide physical support. I'd go for the midrange processors ie at the low end a little more money gives more MHz (considering overall cost of system its good value per MHz). At high end of cpu speeds the incremental performance is not worth the extra cash.

Ideally, run a 64 bit OS.

Personally I'd insert ram in modules of 1GB, and use dual channel memory configuration ie 1+1=2GB per node. That investment in memory will last longer. If on a budget maybe still buy 1GB modules and run them single chan until you afford the rest. 512MB ram modules will likely decline in value faster.

Last fiddled with by Peter Nelson on 2006-12-30 at 08:15
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Old 2006-12-30, 11:17   #8
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Peter,

Sieving for NFS does not require FP. It is however very sensitive to the memory bandwidth. The procedure that we use for NFSNet is optimized to handle the smaller primes in blocks that fit into cache. However, the process quickly becomes dominated by the ability to do "replace add" to widely disbursed elements of a large array of bytes.

Richard
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Old 2007-05-03, 09:56   #9
fivemack
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Quote:
Originally Posted by xilman View Post
NFSNET should be fine on 512M machines. The sievers generally take between 50 and 200M, depending on how big a factorization is being done. Typical is 130M or so.
I have finally got round to getting my credit-card out; 2.2GHz AthlonX2, 2x512M memory (the lattice siever for 2+772 takes 400M), integrated-everything motherboard (I'm a little surprised how few of those there are for Socket AM2), case, and an eight-port gigabit switch. ยฃ200 for the node and ยฃ50 for the switch. Cambridge Computer Recycling on Mill Road will presumably provide a small PATA hard drive if I decide that I can't face bootp; is there a right forum on this site for Stupid Bootp Questions?

If the $10k prize for RSA155 hadn't already been won, a dozen of these nodes would be a cost-effective way to get it but 40 such nodes would by far not be enough to sieve RSA704 in reasonable time, and the matrix would anyway be >>40GB, and there's no good GPL parallel linear algebra. Leave such tasks to people with a State to pay for their systems and make optimising the block Wiedemann algorithm their day job.

One node to start with, see how loud they are, there will be a second node later in this year to use my core2duo once core2quad chips are cheap enough to be worth the upgrade. It looks as if I've missed any Socket 939 fire-sale that might have happened.

Is there an obvious debian-packaged queuing system?
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Old 2007-05-03, 20:50   #10
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Quote:
Originally Posted by fivemack View Post
There will be a second node later in this year to use my core2duo once core2quad chips are cheap enough to be worth the upgrade.
What, you don't trust AMDs claims about their coming quad-cores. ;)
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Old 2007-05-03, 21:05   #11
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Forget network boot and Pentium D; try USB boot and Core 2 Duo.

Get the Core 2 E4300, ASUS P5B motherboard (or P5B-E if you want fancy sound), cheap USB thumb-disk, and some DDR800 memory. Overclock it to 2.7ghz without any trouble or vmods, boot via USB, and consume less power than Pentium D. *Que Windows 95 start-up sound*
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