These pages collect some info to allow Sissa/Democritos users to use our computational resources at best

Please read carefully these pages before asking for help

Currently four Linux Cluster (click here to see all the technical features) are installed in the Computer Room for a total of about 200 CPUS.
Access is granted upon precise policies (see below).
Each cluster comprises a masternode (where the login is allowed) and a series of computationalnodes (where the login is not allowed). Program execution is allowed through a queue system (Torque/OpenPBS): user is asked to prepare small script and then submit it to the computational nodes. Click here for info and examples (link)
Each cluster has its own independent storage and it is a completely independent machine The following table gives an overview of available space for each cluster.
Each cluster has its own username and password (this should be fixed, hopefully, in the near feature)

How to get an account

To ask for an account send your request to cluster-admin AT democritos.it You have to motivate your request clearly indicating:
Each machine (cluster) has its own usage policy so please be sure to read the following before asking for an account. Misunderstood requests will not be processed.

Usage/User policies:

Briareo

Sissa funded cluster available for parallel computations for all the Sissa users. All the regular Sissa users are entitled to use it. Serial computation is not allowed

BaCiuco

Democritos funded cluster for parallel computing. Democritos/Sissa users are entitled to use it. Serial computation is not allowed

Opteron

Machine co-funded by several Democritos/CM research groups. Only users belonging to the funding research groups are entitled to use it.
Each group is assigned a "fair share" of the whole machine resources. "Fair share" means that on average each group can use an amount of CPU hours proportional to what they paid for.
Current fair shares are defined as follows:

Group ID Share
bmf 2/36
carloni 10/36
degironc 4/36
peressi 2/36
schmidt 4/36
sorella 1/36
torre 8/36
tosatti 5/36

FS info can be obtained typing at the prompt

Helium (new)

A machine cofunded by Sissa CED and Sorella's and Micheletti's research groups for serial computing (aka as linux farm). It is available for all the Sissa users but usage will be proportional to the number of cpus funded by each group.

Be sure to subscribe the official cluster users mailing list.

How to login and change the password

To ensure a secure login session, users must connect to machines using the secure shell, ssh program. Telnet is not allowed because of the security vulnerabilities associated with it. The "r" commands rlogin, rsh, and rcp are also disabled on this machine for similar reasons. These commands are replaced by the more secure alternatives included in SSH --- ssh,scp

Before any login sessions can be initiated using ssh, a working SSH client (version 2) needs to be present in the local machine.

To initiate a ssh connection to a machine, type the following on the local workstation

ssh <USERNAME>@<CLUSTER-NAME>.hpc.sissa.it
Note that the <login-name> is only needed if the user name on remote machine differs from the user name on the workstation.

To change the password:

passwd
IMPORTANT:
Password expires within 6 months and the account must be renewed every year.
Use the following command in order to see password/account expiry information:
chage -l <USERNAME>
IMPORTANT on HELIUM and new accounts everywhere
You don't need to insert your own password during logon. Please read carefully our SSH keys-HOWTO to learn about it.

Login Info and Enviroment Setup

The default shell is the bash shell. To change it use the chsh command. At login /etc/motd file is displayed: please take care of reading it, because information about system are usally written there.

A basic default environment is already set up by means of system login configuration files, this includes variables and paths for the all the compilers and their MPI wrappers of the MPI standard, and OpenPBS/Torque batch queuing system with the MAUI scheduler.
Check your environment with the env command. You should be careful modifying the shell customization files (.cshrc .profile .login .bashrc), since they could overwrite the default values altering the behaviour of the compilers and of the batch queuing system.

Plase note again that interactive login is only allowed on the master node. Computing nodes are accessed and used only using the queue system.

Where to ask for help

Any question or request concerning clusters should be sent to cluster-admin mailing list, mail to private accounts will be silently ignored.