Re: help! Octave, connecting laptops to "supercomputers"

[Thomas Weber]

Hi, 

reading through your mails gives me the impression that you have no idea 
what you actually want, sorry. 

If you process data on a host and want to look at a graphics from this
data processing, then this image must be sent to your local machine. It
doesn't matter at all what kind of connection you use; the image must be
sent to your machine. If you need to sync lots of data (like > 10 MB)
over a slow connection, then rsync is the best general purpose solution.

Yes, there are options that are better then forwarding an X connection
to your laptop via ssh. But then it depends on what you want. Because,
if you just want to run a script via the Octave command line, then you
wouldn't even forward your X session, but just run Octave inside GNU
screen or tmux.

On Thu, Jan 31, 2013 at 02:00:33AM +0100, Pedro wrote:
> First of all, Writing this mail I wanted to know what use octavian
> people like me (or not) when need to work with hard processes. 4/4 for
> going in "ssh -X", well, I have to re-think on that!
> 
> I said no to "ssh -X" because I'm looking for alternatives on
> connecting with computer/computers that process the data.
> 
> - I've never used. (read last line of this mail)
> 
> - from ssh -X I read that is innerently insecure, because run a root
> process: the X server, read this (old) review about this [1].
> 
> - Also, because is slow (or inefficient), that's because is encrypting
> all the communications to the server.
> But I only want to "pass the code strictly necessary".
> Because if I use the ssh connection as a workstation it's excessive
> for what I want.
> Imagine looking images, sound or video with a ssh connection in a
> "streaming way".
> I could do rsync? ... Yes, but are things that take you off your
> concentration, no? It means, that make you thing on two machines
> constantly.

I suggest you actually start with ssh and rsync and then solve problems
as they come along. 


> I would like to imagine "one machine", could be with virtualization?
> cloud computing? "p2p processing" ? Assymetric processing?

Your problem definition is so broad that even "pocket calculator" seems
to be in the solution set. What do you actually want to do?

> I don't understand a lot how it works distcc, but see this:
> compilation of kernel distributed: the guy is in his computer, and
> divide tasks to others, after it, they have his output file. [1]
> Compiling means that a personalized task (hardware, processor
> architecture...) but delivered to process by others

distcc is a specialized tool for a very specific problem. In other
words, it is the complete opposite of your approach. 

> For "ssh -X" users, could they give some tricks to make life easier?
Depends; what problems do you have? 

For the record, I used to have Octave running on a 40 node cluster
several years back. One Octave session was started on each host insided
a screen session with 40 windows. Data was put onto the central master node,
home directories were NFS-mounted into each node. Numeric results were
saved on each node into the shared home directory and finally images
from this data was generated on the master node. The only data that I
then downloaded from this system was the images. This worked reasonably
well for me. If your problem is different, then your solution will be
different.

All of this only makes sense if your calculations takes some time. If
you have to wait like 1 minute, then the time to set up your specific
solution will be much larger than the time for the calculations on your
small machine.

        Thomas