The cluster consists of 4 nodes, each having 2 processors, equipped with 6 cores, giving 12 cores per node. In total there are 48 cores (or 96 hyperthreaded cores).
The main node is called octopus, the other ones are named t2, t3, t4. (t1 is identical to octopus).
Ask someone with superuser access to run the script
on the main node octopus. This will add the user, create a home directory, and copy that informations to the other nodes in the cluster. By default the password is set to the same as on ladybug.
Or send an email to email@example.com to request an account. Then read the following:
To log in on the main node run
ssh -Y octopus
ssh -Y octopus.theophys.kth.se
You can also log in to one of the other nodes
If you want to change your password, run
You need to do it manually for each node. Make sure to use the same password on every node, or else…
Accept the default and leave the passphrase empty for simplicity.
Copy your newly created key to
cp .ssh/id_rsa.pub .ssh/authorized_keys
This will enable you to log in to the other nodes of the cluster without being prompted for a password.
The cluster runs a parallel filesystem called GlusterFS, which lets you access your
home directory (
/home/user) on each node.
There is also local storage on each node under
Please create your own directory in
/scratch/your_username and put your files there if you want to use it.
The computer uses as queueing system called “gridengine”.
Write a script which starts the job.
For example, put the following in a file named
#!/bin/sh ./my_program arg1 arg2 > my_results
Submit the job:
Submit 12 jobs:
qsub -t 1-12 start-job
To submit a job to one particular node, e.g.,
qsub -q all.q@t3 start-job
For more info see
To get info about queued and running jobs:
First compile your program with
In order to submit a MPI job you first create a script (jobscript.sh for example) containing the following:
#!/bin/sh mpirun /pathToExecutable arg1 arg2 ...
Please note that the arguments are optional.
Make sure that the long hostnames, including the .theophys.kth.se part, are listed in your
This can most easily be fixed by sshing to the nodes:
$ ssh yourusername@tX.theophys.kth.se
for X=1,2,3,4. You only need to do this step once. (If these are not in the .ssh/known_hosts list and you submit a job with more than 12 processes the job will fail).
To submit a job you have to specify which parallel environment to be used. The environment configured for mpi jobs on octopus is called orte. For example, to submit a job running on 15 cores you enter the command:
$ qsub -pe orte 15 jobscript.sh
The environment orte has been configured to fill the nodes one at a time until a maximum of 48 processes across t1, t2, t3, t4.
Run the followin commands in a terminal
$ . /pkg/init/bash $ pkg math/matlab
Then you can start matlab as usual:
Similar instructions work for maple and mathematica.