MEMWATCH

Section: CCB Memory Watchdog (7)
Updated:
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OVERVIEW

The CCB login nodes are primarily provided in order to allow the submission of jobs to the cluster. cbrglogin3.molbiol.ox.ac.uk is also provided as a large memory login node on which it is acceptable to run large, interactive graphical programs such as R-Studio.

Since the login nodes are a shared resource which can be in use by dozens of people at once, it's not possible for us to permit a single user to monopolise on the resources. As such, a watchdog script runs on a regular basis to identify accounts which are using a disproportionate amount of resources. Where such cases are identified, user processes are terminated in order to protect the health of the system.  

WHY WE DO THIS

As much as we'd like to be able to allow everyone to run whatever they want, the reality is that resources are limited. Furthermore, it is possible for a single user to use so many resources that they cause the system to run slowly for everyone else. In extreme cases, it is even possible to effectively crash the system.  

WHAT HAPPENS IF YOU EXCEED YOUR LIMITS

If we detect that your account is using a disproportionate quantity of memory, the watchdog script will automatically terminate the programs which are using the largest amount. In this way, the likelihood is that your login won't be affected. You'll then receive an e-mail from us to tell you what's happened.

In extreme cases, it's possible for your account to use so much memory that there's a risk of the system becoming unstable. In these circumstances, the script will automatically terminate all of your processes, logging you out. You'll then receive an e-mail from us to tell you what's happened. If this should occur, please do not immediately log back in and repeat whatever it was which caused you to be logged out, as you may potentially crash the login node and cause everyone else to lose whatever they were doing. Instead, please contact us for help.  

GETTING HELP

You can email the CCB team using the email address genmail@molbiol.ox.ac.uk. Using this address ensures your email is logged and assigned a tracking number, and will go to all the core team, which means the appropriate person or people will be able to pick it up.  

COPYRIGHT

This text is copyright University of Oxford and MRC and may not be reproduced or redistributed without permission.  

AUTHOR

Duncan Tooke <duncan.tooke@imm.ox.ac.uk>  

SEE ALSO

cpuwatch(7)


 

Index

OVERVIEW
WHY WE DO THIS
WHAT HAPPENS IF YOU EXCEED YOUR LIMITS
GETTING HELP
COPYRIGHT
AUTHOR
SEE ALSO