beowulf in space

Robert G. Brown rgb at phy.duke.edu
Mon Apr 14 13:53:07 EDT 2003


On Mon, 14 Apr 2003 chettri at gst.com wrote:

> Has anybody considered the theoretical aspects of placing beowulfs on a 
> cluster of satellites? I understand that communication will be slower AND 
> unreliable,
> and it would restrict the set of problems that could be solved. I'm looking 
> for papers/tech reps etc on the subject.

Well, let's see.  Beowulfs for what purpose?

As far as building general purpose computational supercomputing centers
in space, that is such a phenomenally silly idea that anyone that DID
have it would probably shake their head after a minute or two of
reflection and resolve never to use those particular drugs again.

As you say, problems include:

  a) expense 
  b) communications latency (bandwidth actually can be as big as you
     like or are likely to ever need, since you ARE a satellite, after
     all...:-)
  c) access/maintenance difficulties 
  d) expense 
  e) cooling (think of the cluster as being located a really big vacuum
     flask)
  f) onsite staff (astrobots?  astroadministrators?)
  g) radiation and shielding
  h) energy supply
  i) hard to get 24 hour turnaround on spare parts
  j) did I mention expense?

Even if you think about some sort of space station as being just another
cluster room and the cluster nodes being just off-the-shelf units from
Dell, you're looking at one hell of a delivery charge...

Now, with all of that said, it may be perfectly reasonable and sane to
send small clusters aloft -- I suspect that we already do, every time we
launch a shuttle or send experiments up.  Many modern jets are
architected like a "cluster" in many ways, with sensors and processing
units all over the place, interconnected by a network of sorts.  A
compute cluster has a lot of desirable features -- an extension of the
available total computational power that can be brought to bear on
certain problems, for example, in addition to some highly desirable
redundancy (if a node dies out of five or six you've got, you can
proceed to function a bit slower -- if a system dies and is all you've
got, you're in a lot more trouble).

The "problems" that would be solved are thus restricted by common sense
-- dedicated tasks in many cases to accomplish some specific purpose, or
MAYBE a very small general purpose cluster on something like a space
station doing science that happened to need some local processing power.
In most cases, though, it would still make more sense to locate the
processing power on the ground and use a dedicated comm channel to the
ground to access it.  Something out in space has an excellent vantage
point to establish high bandwidth (high latency) with any number of
ground stations.

   rgb

> 
> Regards,
> 
> Samir Chettro
> 
> 
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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



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