ALIs

kommt noch

How to access the LRZ Linux Clusters

Table of contents

User Access and Support

In principle, scientists and students from Munich Universities as well as Bavarian Universities can obtain access to the LRZ Cluster Systems. The following steps need to be performed before attempting the first login to the systems:

  • A valid LRZ account is required, which can e.g. be obtained by contacting the responsible master user located at your institution. Further details on LRZ accounts are described on the LRZ web server.
  • You need to fill in a project proposal, providing details about your intentions and needed resources.

If your project is approved, you will receive access information after at most a few working days.

Questions concerning the usage of the Linux Cluster should be directed to the LRZ HPC support team, preferably to the Linux-specific mailing list mentioned there. A member of our support team will then attend to your needs.

Login and Security

Only the login nodes  can be accessed interactively from the outside world. Two mechanisms are provided for logging in to the system; both incorporate security features to prevent appropriation of sensitive information by a third party.

Access via Secure Shell

Details on how to configure ssh for usage with the LRZ clusters are available in a separate document.

From the UNIX command line on the own workstation the login to an LRZ account xyyyyzz is performed via one of the commands given in the following table.

ssh -X lx64ia2.lrz.de -l xyyyyzz Opteron (x86_64) login node
ssh -X lx64ia3.lrz.de -l xyyyyzz Nocona (EM64T) login node
ssh -X ice1-login (from one of the above nodes) ICE1 login node
ssh -X lxa1

or

ssh -X lxa178

(from one of the above nodes)

 MPP Cluster login node
gsissh -X lxgt2.lrz-muenchen.de login node for Gsi-SSH

Please do not forget that login resources should not be overused since you share the cores with all other users. Do not start any long running or memory intensive (>10GB) programs within login shells.

For testing of programs that requires runs of more than a few minutes, an interactive SGE job should be used.

Notes:

  • The -X option of ssh is responsible for tunneling of the X11 protocol, it may be omitted if no X11 clients are required, or if you already have otherwise configured X11 tunnelling in your ssh client.

  • The HOME directory on the Linux Cluster is an NFS mounted volume, which is uniformly mounted on all cluster nodes.

  • The login nodes have various architectures. In particular, a program built on an Itanium system will not run on an Opteron/EM64T system and vice versa.

Secure Shell Public Keys

The Secure Shell rsa public keys for the interactive nodes are given in the following link (please add these to ~/.ssh/known_hosts on your own workstation before logging in for the first time):

SSH Public Key

Login via Grid Services using GSI-SSH

An alternative way of accessing the cluster is to use GSI-SSH, which is a component of the Globus toolkit and provides

  • terminal access to your account
  • a single sign-on environment (no password required to access other machines)
  • easy access to a number of additional functionalities, including secure and parallel file transfer

The prerequisites for using it are

  • a Grid certificate installed on your machine and acknowledged by LRZ, as described on the LRZ Grid Portal. Please note that TUM, LMU, and LRZ members can use the new and easy short lived credential service (SLCS) of the DFN as an alternative: it allows you to immediately obtain a certificate for Grid usage
  • an installation of a GSI-SSH client on your own workstation, either the command line tool gsissh or the multi platform Java tool Gsissh-Term, as described on the LRZ Grid Portal.

LRZ-specific configuration of the clusters

Changing of Password and Shell

Please use the web interface on the LRZ server to change your login password or your login shell for the cluster systems.

Note: The command /lrz/sys/bin/chsh which previously was available for changing shells will not work any more.

Using the cron or at commands

This is not allowed on the LRZ cluster. Please submit SGE batch jobs for performing computations.

Moving data from/to the cluster

ftp access to the cluster from outside (and also within the clusters) is disabled for security reasons. Please use scp (Secure Copy) or grid-ftp to move data between platforms.

Firewall, networking

The cluster is protected from certain types of external attacks by a firewall, the configuration of which may impact the functionality of certain applications as described in the following.

X11 Protocol

Direct X11 connections (via xhost or xauth) are prohibited, only ssh tunneling is supported.

Routing

None of the batch nodes in the cluster are by default routed to the outside world. Please contact LRZ HPC support if you require a particular system to be routed to the batch nodes.

Electronic mail

We recommend to not use the Linux Cluster for mail purposes; should you nevertheless need to do so, please note that you need a POP3 or IMAP capable mail client (thunderbird or alpine); the mail, mailx programs cannot be used for receiving mail. For sending mails it is required to specify a valid sending as well as target mail address; simple programs like mail therefore need an additional command line argument.

Documentation

Protected Documentation for Compilers, Libraries and Tools

Part of the software documentation (especially commercial development software) is password protected. Please log in to the Linux Cluster and type

     get_manuals_passwd

to obtain the user name and password required for validation.

Documentation for Application Software and Packages

Please start from the Application Software entries on the LRZ web server.

General Linux System Documentation

Typical for Linux systems there are (at least) two formats for the system documentation:

  • man pages

  • info pages

Access to both is seamlessly integrated into the KDE help system. Calling the browser via

khelpcenter &

causes the following window to appear, in which all required entries can be found under "KDE Help Contents":

khelpcenter.png (42 kB)

Advantage of khelpcenter: Hyperlinks to cited man and info pages are available. Searching only works within the opened page, though.