On 19/06/2007, at 7:58 PM, Robert G. Brown wrote:
On Mon, 18 Jun 2007, Ellis Wilson wrote:
Thanks Brian, Matt, and rgb,
The floppy idea is great (I think I remember now reading about it in
rgb's book, but had forgotten), and I certainly will look into that.
The motherboards are in some cases years and years old; one
computer I'm
deciding whether I'll use or not does have a 400mhz processor in
it, so
their age is sufficient to make me worry.
Two points. One is that these days if your system has a BIOS that can
manage booting from CD, I'd advise booting from CD instead of floppy.
There are a variety of reasons for this -- CD's are cheap, you can
put a
large kernel on it, you can actually put a whole linux image on it and
avoid having to "boot diskless" over the network, although of
course you
can still do that as well. Floppies are pretty much obsolete at this
point and it isn't easy to get a properly bootable image of a modern
kernel to live on one -- I think you'll find building tight kernels
that
will fit moderately frustrating.
I disagree that floppies are obsolete! But putting the kernel on the
floppy is. On our old cluster we used floppies with a custom build of
grub (easy to do). Just build grub with support for the network
adapters in your cluster and throw in a config file. The config file
can list any number of boot kernels (and optionally associated root
paths) which is really handy for having eg a production kernel, a
debug kernel, a testing kernel, memtest, etc. Though the grub config
file is hardcoded into the binary which is not ideal. When I had to
create new grub configs it only took a few minutes to dd the floppy
image. Far, far quicker than burning 20 copies of a CD.
The same technique can be extended to modern computers with PXE Grub,
which is even better because the config file can be sucked off the
TFTP server too.
Second, remember that one dual dual core 64-bit opteron processor
system
-- currently available for maybe $1600 if you shop hard -- is going to
be faster than a 32 node 400 MHz P6 cluster, and the latter will cost
around $3000/year to leave powered on 24x7 (estimate $1/watt/year,
even
if you're not paying for it...:-). So you're building your cluster to
learn and have fun, not for speed or to save money. If you have real
work to do and want to do it as cheaply as possible, it would be wiser
to go with a very small cluster of dual core 64 bit modern CPUs.
Very true. But it is usually someone else paying for juice. Though
logically I should be able to go to the building management people
and say 'I can save you $1000 if you give me $2000' in practice I
don't think it would work...
One other thing to play with that can suck you right in but that
should
prove to be very rewarding in the future is virtualization -- look
over
vmware-player and the library of VM appliances, including prebuilt
ready-to-play cluster nodes.
I can highly recommend this approach if you need to run stuff on
windows. Far easier to netboot linux and start a vmware instance than
to try to netboot windows (though emBoot makes things easier).
Regards,
Andrew
_______________________________________________
Beowulf mailing list, [email protected]
To change your subscription (digest mode or unsubscribe) visit
http://www.beowulf.org/mailman/listinfo/beowulf
