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Usage guidelines

The Ponyland cluster is a powerful tool for getting your calculations done quickly, in particular if you use multiple cores or even multiple ponies simultaneously. This power, however, is not unlimited: if you use all cores on all ponies, you will slow down other jobs by other people that are running at that same time.

At some other clusters SGE is used to divide the resources. For Ponyland, however, we decided we do not want to force people into using SGE for a number of reasons, the most important ones being the desire to work from a local scratch disk for faster I/O, or in a more interactive session using screen or tmux.

To make sure this freedom to avoid SGE does not mean everybody tries to use all of the ponies all the time, a number of guidelines have been composed:

  1. Non-SGE users always check top or htop (a little more visual) to see if a server has sufficient resources, and they monitor their processes as they run.
  2. No single user takes all the resources of a single node (or all nodes). System load shouldn't exceed the number of cores (32 with hyperthreading).
  3. SGE users keep within the SGE-constraints (i.e. submitting to the right queue, anything that is inherently multithreaded should go in 'multicore' queue instead of short/long, SGE queues have been set up in a way that no single person can claim all resources but SGE does little monitoring or enforcing).
  4. Communicate and coordinate with others running things (our IRC Chat chat is a good medium for that ;) ).. even an SGE can't replace communication.
  5. Never use Applejack for experiments. Applejack is reserved for websites and webdemos.
wiki/ponyland/guidelines.txt · Last modified: 2014/03/07 14:48 by Wessel Stoop