Hierarchical storage

The High Performance Storage System (HPSS) service is a system capable of storing very large quantities of data with a relatively good performance for write and read operations.

Note

HPSS is not an archival system, and stores only single copies of files.

File access and management

File management on HPSS is based on the RFIO API. To source the RFIO environment, please load “shift”:

% ccenv shift

Here are the most common commands to manage files with RFIO:

rfcp          # remote file copy
rfchmod       # change file access permission
rfdir         # remote directory list
rfmkdir       # make remote directories
rfrename      # rename remote file
rfrm          # remove remote files and directories
rfstat        # get information about a file or directory

These commands should be used with the RFIO server cchpss0, in the following way:

% rfdir cchpss0:/hpss/in2p3.fr/group/alice

It is possible to use local symbolic links pointing to remote HPSS directories, like:

% ln -s cchpss0:/hpss/in2p3.fr/group .
% rfdir group
drwxr-xr-x  79 root     root                     1536 Jun 03 10:38 .
drwxr-xr-x   4 root     root                      512 Mar 27  2017 ..
drwxrwxr-x   7 tmaterna mnm                       512 Mar 27 10:28 mnm
drwxrwxr-x   2 aubourg  sdss                      512 Apr 14  2009 sdss
.....

Finding a file in the HPSS tree can be slow. In case of frequent calls to find a file in HPSS, we recommand the use of a dedicated database or catalogue.

File permissions

File permissions on HPSS work in the same way as standard Unix permissions. Keep in mind that rfcp propagates the original file permissions to the new copy.

Access from jobs

To access HPSS from a job run on the computing platform, please use the -l option at job submission:

% qsub -l hpss=1 script.sh

File size

HPSS supports a maximum file size of 64 GB. In order to benefit from better I/O performance, users are invited to store large files (> 1GB) in HPSS, the optimum being 4 GB.

I case you need to store a large number of small files, please contact the user support.

File transfers

The HPSS service at CC-IN2P3 allows direct remote file transfers from the outside using bbftp.