The SCore Multi-User Environment

The figure below shows an example of the SCore multi-user environment. Conceptually, the multi-user environment is very similar to the single-user environment. The only difference being that scout and scored are executed by the root user on a host machine in the network, and user's execute scrun commands specifying the host where scored is running. Thus, multiple users can execute programs on the cluster based on the scheduling policies of scored executed by the root user.

Suppose that you have a cluster of eight compute hosts, i.e., comp0 through comp7, and a server host running the Cluster Database Server (scoreboard), the Compute Host Lock Server (msgbserv), and root has started scout and scored processes.

Here is an example session to execute the hello command on the cluster:

	$ msgb -group pcc
	$ scrun -nodes=8,scored=comp7 ./hello
	SCORE: connected (jid=100)
	<0:0> SCORE: 8 hosts ready.
	Hello World! (from node 2)
	Hello World! (from node 5)
	Hello World! (from node 3)
	Hello World! (from node 6)
	Hello World! (from node 4)
	Hello World! (from node 7)
	Hello World! (from node 0)
	Hello World! (from node 1)
The procedure to execute hello is as follows:
  1. scrun is issued by the user to execute the program. It requests scored, running on host comp7 (the default host is the last host in the cluster group), to execute the program on 8 of the compute hosts.
  2. scored requests the scored processes running on the cluster hosts to fork and exec the user's program which will execute until completion. When the program completes, the user processes are terminated.
SCore Multi-User Environment

It should be noted that the Compute Host Lock Server is continuously locked by the scored process running on the server host. This disallows other processes to lock the Compute Host Lock Server and execute their own programs.

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$Id: env_multi.html,v 1.2 2002/03/08 06:24:17 hirose Exp $