Interactive servers usage best practicesΒΆ

CC-IN2P3 provides interactive servers to prepare tasks before they are submitted to he computing platform: development, test, etc. Interactive servers are accessible with the following syntax:

% ssh -Y username@cca.in2p3.fr
  • cca.in2p3.fr is an alias that redirects to the least loaded server.
  • For Microsoft Windows users we recommend the use of PuTTY as an SSH client.

As each interactive server is shared by multiple users, we recommend a number of good practices to follow so that your activities can coexist with the other users activities.

Attention

Non compliance with these rules may result in some of your processes termination.

  • Only one computing process is allowed per interactive server and 3 processes over the entire interactive platform.
  • 24 hours CPU time maximum for a process and 1 hour CPU time for a multi-core process.
  • Parallel processes with intensive use of both CPU and input/output are not allowed (example: make -j, scons, b2, ninja, etc.) However, it is possible to run such processes as interactive jobs (see interactive jobs).
  • Avoid excessive memory consumption that could have an impact on the system. The command htop -u username may be a useful monitoring tool.
  • It is forbidden to run tasks in “batch” mode (eg: processing a large amount of files in loop).
  • /scratch is not a permanent storage space: data can be deleted at any time to free up space. Under normal circumstances data is deleted after 14 days. Also, avoid large data storage.
  • Detached and persistent processes after logout are not allowed (excepted when using Screen).
  • Please note that screen is neither meant as a substitute to the batch system, or as a way to run services nor as a way to hog scarse resources (like GPU interactive computing nodes).
  • Processes inactive for more than 24 hours are killed.
  • One transfer process is allowed per server (example: scp, rsync or dq2-get) and 3 processes across all interactive servers.
  • To preserve user data confidentiality, rmate (or other similar editor) requires using a random TCP port instead of a fixed port.