Nuredduna Computer Cluster

Nuredduna Mosix Software

Software Configuration

Operating System

• Operating system for nuredduna is Ubuntu Server 64 bit edition with the last available Linux kernel patched with MOSIX.

• All nodes boot via the Ethernet network and load the Operating System from the IFISC disk server dolsa, so all of them share the same settings.

• Network is set up so all nodes can be accessed directly from any computer inside IFISC VLAN.

• Users have the same home directory as in all the other IFISC computers including desktops and servers.

MOSIX

• MOSIX (http://www.mosix.org) is a patch for the Linux kernel plus some utilities running in the user space that enhance the Linux kernel with cluster computing capabilities.

• Trough that software layer, users see the cluster as a single Linux computer.

• MOSIX allows applications to run in remote nodes, as if they where running locally:

• Kernel patch intercepts all system-calls.

• Migrates processes without interrupting the calculation.

• For migrated processes, most of the system-calls are forwarded to home-node, performed there, and results are sent back to the process.

• A few system-calls can be performed directly on the remote node.



• MOSIX distributes the computational load among the nodes dynamically:

• Each node calculates its load: # programs / (#cores*speed).

• Every few seconds each node compares its load with another one randomly.

• The load of these two nodes is balanced by migrating one or several programs.

• Over the time this averages the load automatically without any "central authority".

• If one node has to be shut down, MOSIX first migrates to another node the programs that have been sent there. That eases maintenance tasks.