[Beowulf] Possibly OT

[Robert G. Brown]

On Tue, 25 May 2004, Ed wrote:

> Hi, Im very new to clustering. I have a perhaps very simple question:
> 
> I have to provide a webhost, but with low spec computers which we have
> in abndance.
> 
> Now, I assume that the webservice will use the single IP address
> x.x.x.x.
> 
> However, I have not got a clue how to go about this. Should I aim to
> have two single computers linked via a serial interface, or should I do
> something more adventurous such as link them via a network interface. Am
> I asking on a list where Beowulf is a API and only certain programs will
> work with Beowulf?

This isn't high performance computing (HPC) -- this is high availability
computing (HAC).  So this is indeed the wrong list for this.

Most of the issues that you raise have long since been solved.  There
are round-robin and/or load balancing daemons that manage connections
and farm them out to a cluster of servers.  For example, see:

  http://www.webopedia.com/TERM/R/Round_Robin_DNS.html

for RR DNS (which may or may not be the best way for you to proceed --
there are alternative load balancing tools to consider as well).  Some
of the projects (for linux) are summarized here:

  http://lcic.org/load_balancing.html

LVS is probably where you should start.  That would be:

  http://www.linux-vs.org/

I believe that this is a fairly mature project and in fairly widespread
use.  I don't use it myself so I couldn't tell you if it is prebuilt in
standard distros ready to roll or if you'll have to build your own
packages from the GPL sources, but if you're building a serious HA site
even the latter shouldn't be too onerous.

> 
> This is probably a question that has been asked many times. But if
> Beowulf can control computers and spawn instances of daemons for mail
> as mail arrives it would also solve many of the mail problems which we
> currently face in the small hosting organisation where I work. Currently
> I spend many hours researching this question, however fruitless.

Remember, Google is your friend.  "load balancing web server linux"
turned up a huge amount of information in a few seconds.  Google is
ALMOST the only "research tool" I use anymore, the exceptions being
abstract searches (which tend to be sold services, likely managed
through a HA server:-).

HTH,

  rgb

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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