[Beowulf] disabling swap on cluster nodes?

[Matt Wallis]

Hi Prentice,


> On 7 Feb 2015, at 9:35 am, Prentice Bisbal <prentice.bisbal at rutgers.edu> wrote:
> 
> Do any of you disable swap on your compute nodes?
> 
> I brought this up in a presentation I gave last night on HPC system administration, but realized I never actually did this, or know of anyone who has. I would tweak the vm.overcommit_memory setting, but that's not the same as disabling swap altogether. I'd like to try doing this in the future, but I prefer to learn from someone else's mistakes first.

Yeah, I don't think it's a good idea to disable swap entirely, I believe there was an article on one of the Linux magazines a few years back suggesting that at least some swap is an essential part of Linux memory management. Typically we keep it low, and as you suggested, use the vm.overcommit_memory, and also vm.swappiness to make sure that it only uses the swap when to do otherwise would be to crash the machine.

This might be a good article to read http://www.linuxjournal.com/article/10678

Matt.