Getting Started

Getting Started on NECluster - Windows

SSH Client

To connect to the cluster you will need an SSH client. The easiest one to use, in my opinion is PuTTY. You can either download a standalone executable, or use the installer to install everything.

Once you've installed PuTTY you can just run it. A dialog window will pop up asking for some information. In the Host Name box you enter necluster.engr.utk.edu. Make sure the port is 22 and that SSH is checked. If you have a X Window Server (discussed next) and wish to use it, you also have to go to the X11 Category and put a check mark in the box next to Enable X11 forwarding. Note that on the first screen you can save your settings so that you don't have to type this in every time. Once done, click Open and enter your user name and password when prompted.

• PuTTY
• PuTTY01.png

  Basic Options

• PuTTY02.png

  X11 Forwarding

• PuTTY03.png

  Entering User/Pass

X Server

If you want to use some of the GUI programs on the cluster, you will need to install an X Server on your machine. A nice freeware X Server is Xming. When downloading Xming, first install the pacakge Xming and then install the package Xming-fonts. If you desire you can install Xming-mesa instead of Xming for additional graphics capabilities that probably won't be used over a network connection anyways.

Once Xming is installed, you can run it from the start menu. It may seem like nothing is running after you click it, but if you check the application area of your task bar, you should see the Xming icon.

File:Xming01.png

Xming is running!

Note that you can start Xming before or after you start PuTTY. As long as you forwarded your X connection it will work.

Getting Started on NECluster - Mac/Linux

If you're running Mac OS X or any version of Linux it's even easier to get on the cluster. You generally already have a SSH Client and X Server installed! To log on to the cluster open up a terminal window and type the command:

ssh -X -l user necluster.engr.utk.edu
OR
ssh -X user@necluster.engr.utk.edu

The -X forwards the X connection. You can omit it if you don't plan on using any programs that use it. Like Windows, most terminal programs allow you to save sessions that you want to use regularly.

First Time on the Cluster

Changing Password

The first time you're on the cluster the very first thing you will want to do is to change your password away from the temporary one that you were assigned. This is done by using the passwd command on the file server:

First SSH onto the file server:
user@necluster:~$ ssh nefiles

Note: The first time you log on to any node, you will have to add that node to your known_hosts file. This is done by saying answering in the affirmative at the following prompt:

The authenticity of host 'nefiles (192.168.100.50)' can't be established.
ECDSA key fingerprint is a0:7c:55:f8:da:24:80:0b:b9:62:bc:8c:25:cf:cd:34.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'nefiles,192.168.100.50' (ECDSA) to the list of known hosts.

Now you can change your password:

user@nefiles:~$ passwd
Changing password for user.
(current) UNIX password:
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully

Now, log off the file server by typing:

user@nefiles:~$ exit
logout
Connection to nefiles closed.

Your password has been changed!

Getting on Other Nodes

When you first log on your prompt will be:

user@necluster:~$

This shows that you are on the head node. When you run cases you'll want to run them on one of the many compute nodes that you can find on Ganglia. They are named node# where # is the node number. To connect to one of these nodes you can just SSH to it:

user@necluster:~$ ssh node15
Cluster MOTD Information
user@node15:~$

If it is your first time on the node, you will have to verify the authenticity like you did when you connected to the file server to change your password. If you have a few minutes you can run a script to connect to every node in a list so you can just type yes about 30 times and then not have to worry about it.

This is the current incarnation of the script:

#!/bin/bash
for i in {1..30}
do
  ssh node$i hostname
done

I have the script in my home directory, so instead of copying the script out yourself, you can just run it from my directory as follows:

user@necluster:~$ ~shart6/test_nodes

Common Problems

Every once in a while the fingerprint of a node will change. When this happens