[Beowulf] small file systems

[Robert G. Brown]

On Mon, 27 Aug 2007, Jim Lux wrote:

> And here's a challenge at the other end of the spectrum.
>
> What's the lowest cost, simplest, closest to off the shelf way to build a 
> small network file server that can do DHCP/PXE booting, etc. for a compact 
> low power cluster.  Something like a LinkSys NSLU-2 (<$100 but you need to 
> add a USB disk, and load a new version of the OS that has dhcpd and tftpd) 
> could probably do it, but it would be nice to have an integrated solution.

An intriguing problem, but if you are serious I think you'll have to
specify your requirements and the relative weight assigned tradeoffs a
bit more carefully.  USB flash >>is<< remarkably cheap nowadays
(although often slow unless you spend a bit more than the minimum) and
there are a variety of very small devices, e.g. phones and PDAs and
PDA-phones capable of running an OS, networking, and attaching a USB
device or a flash chip directly.  Then there are Slugs, and then there
are micro-ATX form factor motherboards, and then there are chopped up
laptops.  Neowares have a "system unit" that is built into the monitor
and is about the size of a trade paperback -- with video, networking,
etc.  They take a USB flash snap-in.  If I bought one and chopped it up
and kept only what I need I could probably make a server with a 48 GB
RAID built on top of (say) four 16 GB flash sticks, a USB bridge, a
neoware's guts, and a small brick that wasn't too big and would probably
have decent performance and no moving parts (no fans, no disks).  It
would cost a few thousand, though.

OTOH, there are on-web HOWTOs on how to e.g. set up a Sharp Zaurus with
linux, and of course there are many embedded linux capable devices out
there at this point.  There are many single board computers that will
run linux or e.g. Windows CE.  Many of them will run a remarkably
full-featured linux.

Truthfully, I think that if one really pushed it, one could probably
build a 50 GB solid state device (no moving parts) inside one of the
small "paperback" portable USB disk enclosures like the one I have for
my laptop.  One could likely power it off of a USB cable or a small
wall-wart, and serve the disk either over ethernet or 802.11b.  It's
pretty easy to find functional motherboards this size or smaller for
prices as low as $52:

   http://www.compulab.co.il/x270cm/html/x270-cm-datasheet.htm?gclid=CIX86d3slo4CFR5uUAodVT-jQQ

with all the integrated peripherals required to make a nice, little,
SLOW system.  Where slow means less than a GHZ -- I've run NFS servers
for entire departmental LANs on systems with 20 MHz clocks, though.  My
current palm pilot has a 400 MHz clock, integrated wireless, etc.  If
one wired the flash directly onto the motherboard and got rid of the
dongles and everything, you could probably build an NFS server the size
of a credit card about a centimeter thick.  Or, if I spent a few
entertaining days learning to code my Palm, I could probably make it an
NFS server for at least a small (probably tiny) filespace -- however big
a memory chip add on it would accept.

So, if this is a "challenge", what are the parameters, and what are the
stakes?  I'd bet that ~50 GB for a kilobuck, wireless or 100 Mbps
ethernet, inside the size of a paperback, add your own KVM would be
"easy" at the hobbyist or homebrew level.  That's based on 4x$130 = $520
for 4 16 GB USB flash disks, $100-$200 for a single board low power
computer (depending on features selected etc), $50 for building an
enclosure, $30 for power, and a big slop budget for places I'm
underestimating.  For about the same one could probably do 360 GB with
4 actual laptop hard disks, but I'm not sure you could get it into as
small an enclosure and keep it as cool...

    rgb

>
>
>
> James Lux, P.E.
> Spacecraft Radio Frequency Subsystems Group
> Flight Communications Systems Section
> Jet Propulsion Laboratory, Mail Stop 161-213
> 4800 Oak Grove Drive
> Pasadena CA 91109
> tel: (818)354-2075
> fax: (818)393-6875 
>
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-- 
Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu