The login nodes of Louhi see the following directories of the CSC environment: your home $HOME, the archive $ARCHIVE, the metawork $METAWRK, and your project directory. The compute nodes do not see these directories.

The most important directories that the compute nodes do see are the work directory $WRKDIR, and /v/users/$LOGNAME for user's own applications and programs. These are shared between all the compute and login nodes on Louhi. Both directories are local to Louhi and are on the fast Lustre filesystem.  $LOGNAME is an environment variable, whose value is your User Id (Login Name). For performance reasons you should install your own applications under /v/users/$LOGNAME and launch your batch jobs from $WRKDIR and generally use it for your batch jobs.

Your home directory $HOME on the CSC computing environment is located on the disk server. The files in your home directory are shared between the login nodes of Louhi and other computing servers at CSC. The home directory is suitable only for small initialization files and frequently used small programs. It is not intended for extensive I/O operations or for large data sets. Therefore, before running a job it is highly recommended to copy all needed files from your home directory to the local work disk for performance reasons.

There are several file storage areas available for users. Usually you need not (and should not) refer to directories with full path names. Instead, use the defined environment variables. The most commonly used storage areas are listed in Table 2.1. The lifetime of files in each directory is limited as described in the table.

Table 2.1: File storage areas available for users.

The home directory $HOME is backed up regularly. This directory is meant for permanent files, with a maximum total size of a few megabytes. It is a typical repository for source codes and small input files.

The local working directory $WRKDIR is common for all Louhi nodes. However, since no backups are taken, a disk crash may destroy the contents of the directory. Unmodified files will be deleted after a month. NB: deletion will be activated on a later date. Therefore, if you have installed your own applications and programs here, you should move or reinstall these under the directory /v/users/$LOGNAME.

The local user application directory /v/users/$LOGNAME is common for all Louhi nodes. Backups are taken regurlarly. If the subdirectory $LOGNAME does not yet exists you should ask the User Manager (usermgr@csc.fi) to make it. This is now the place where you should install your own applications.

The directory $METAWRK is shared by all the machines in the CSC computing environment. Because this directory is not local it is slower to use than the directory $WRKDIR and it is available only on the login nodes.

The directory $ARCHIVE refers to the archive server. This is not a local filesystem, and it should be used only for long-term storage of compressed and infrequently used files. The access time to the archive server can be very slow because usually the data resides on tapes. The directory $ARCHIVE is available only on the login nodes.

The directory $TMPDIR of Louhi login nodes is really memory and not disk and it should not be used explicitely at all - it can be automatically used by the compilers.

For the best file retrieval performance, avoid storing a large number of small files. Instead use the tar utility to archive a number of files and/or directories into one file. For example,

tar -cf example.tar mydirectory

creates a file example.tar containing the whole directory structure and all the files of the directory mydirectory.

To extract the tar file issue the command tar -xf example.tar and the ”tarred” files with the directory structure will be extracted under the current working directory. The files are stored in the archive server for 22 months from the last modification date.

You can use the command

quota -v