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Access to the sigma cluster


The sigma cluster login system is integrated with the central authentication system of IST, which means the user makes the login by using the Técnico ID credentials. To login in the sigma server, the user only needs to have a secure shell (SSH) client.

In the case of Windows users, the access can be made through any ssh client.

Regarding the Linux and MAC OS X operating systems, the login can be made using the “ssh” command in the console:

  • $ ssh -l [username]  , in which [username] corresponds to the Técnico ID, i.e., istxxxxx.

After logging in the sigma server, the user will be presented with the following prompt:

  • istxxxxx@sigmayy ~ $

where “istxxxxx” corresponds to the user’s Técnico ID and “yy” is a number between 01 and 04, which represents the sigma node in which the client was redirected.


The sigma cluster is integrated with the AFS storage technology. When the user logs in any of the sigma nodes, its workspace corresponds to the private workspace in the AFS system. For more information about the AFS system, check the following article.

Direct access to a specific node

When a login is made in the sigma cluster by using the generic name “”, the login is redirected to a certain cluster node, based on the availability and load of the nodes (the redirect is made through a load balancer system based in LVS).

Despite the access to the generic name “” is the recommended way of accessing sigma, it is possible to access a specific node by using the “sigmaxx” name in the login, where“xx” represents the number of the node.


  1. I need to compute for my thesis. Can i do it on Sigma server? Not properly, because each node only has 16GB RAM.