1.2 Operating system and shell environment

Taito is a Linux cluster. The login nodes are based on the RedHat Enterprise Linux 6 (RHEL6) distribution, while the computing nodes use CentOS 6, which is a free distribution entirely derived from RHEL6. During the lifetime of the cluster, we aim to keep the software packages up to date following the minor releases of the operating system, as long as this preserves the necessary compatibility with the previous versions. The computing nodes have identical software configuration. The same applies to the login nodes. The system software set installed on the login and computing nodes is relatively minimal but it offers a wide selection of libraries and development packages to compile your own software. In general, all the libraries available on the computing nodes are also available on the login nodes. You can inspect what packages are installed on Redhat based servers using the following command:

rpm -qa

This command is also useful to find out what is the version of an installed package. Other options can be given to the rpm command to inspect the system configuration. Alternatively, locate and find are also good tools for inspecting the software configuration of a system. Note that users can't use rpm command to install software to Taito.

The system packages will be updated during the lifetime of the system without any previous notification. Therefore, we suggest using the module system to load specific library versions and software supported by CSC, or install your own version in $USERAPPL directory. In this way your software dependencies will be safely preserved.

As a general rule, x86-64 binaries should be used for software installed on Taito. "x86-64" is the 64-bit extension of the x86 instruction set.

The default and recommended command shell in Taito is bash. Previously CSC has been using tcsh as the default command shell and you can still continue to use tcsh shell in Taito too. If you want to change your default shell in Taito, please contact servicedesk@csc.fi.

When a user logs into Taito, the bash start-up script defines a set of CSC specific variables defining the location of the user specific directories: $WRKDIR, $HOME, $TMPDIR and $USERAPPL. Further, rm, cp and mv commands are aliased so that by default they ask for permission before removing or overwriting and existing files. Also the clobber options are set up so that output forwarding does not overwrite an existing file.

If you wish to add more settings or aliases that are automatically set-up when you log in, you should add the corresponding linux commands to the end of the bash set-up file .bashrc that is located in your home directory.

The Taito system supports UTF-8 character encoding, which makes it possible to represent every character in the Unicode character set. UTF-8 was not supported on older CSC systems, so care should be taken when sharing files with other systems.

Compiling programs should be done in the $TMPDIR, which is login node specific instead of $WRKDIR or $HOME which reside on Lustre file system. Using $TMPDIR is much faster for compilation purposes than Lustre and avoids performance degradation for computing jobs.


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