can you have 4 operating systems on one buss?

Posted by Marcus G. Daniels on Mar 28, 2008; 6:18pm
URL: http://friam.383.s1.nabble.com/Wed-Blender-Stereo-and-Computational-Photography-Videography-for-Cultural-Preservation-tp525972p525985.html

sy at synapse9.com wrote:
> Now that since nearly anyone's taking of more resources is increasingly robbing and disrupting other users, has sort of become the main source of conflict on earth..
>  
If someone wants to copy a real big amount of stuff from one node of a
cluster to another (there can be tens or thousands of these nodes), the
switch can connect these two nodes.  All other transfers in the system
can be going on without notice of this.   To the extent other people
want to deal with those two nodes, the switch can fairly divide down the
bandwidth between those people.   This will typically be a small
fraction of the total capacity of the system or the network.    
Furthermore, on a typical large cluster, there will be a parallel
filesystem with many independent block devices and very low latency
switches.   If I have 100 nodes all writing at once to 100 different
block devices and there is a effectively a different wire from the node
to the drive, then there is no contention.

If a hundred users all want to do this, with their respective
entitlements, and from different nodes, then at some point you run out
of gas.   But a hundred users rarely if ever all want to do this.   This
is a pretty standard assumption of many kinds of telecommunication systems.

So, neither wire networking nor bus use is usable for your analogy.  
The reason is that these resources can be managed by a secure executive
process that divides up the work fairly.   Systems that don't do this
are non-critical systems.

Marcus