out of swap space

[Reed A. Cartwright]

We've run out of swap on a system with 512GB of memory and 1TB of swap space.

Processes get killed, including services.  It is usually easiest to
reboot to start from a fresh system.

The funny effect is that you can log in to SSH and get a shell, but
cannot run any binary that is not already cached in memory.  That
confused the hell out of me until I checked memory and swap usage.

On Tue, Oct 28, 2014 at 6:01 AM, RW <rwmaillists at googlemail.com> wrote:
> On Mon, 27 Oct 2014 16:39:52 -0500
> Adam Vande More wrote:
>
>> On Mon, Oct 27, 2014 at 2:57 PM, Jim Pazarena <fquest at paz.bz> wrote:
>>
>> > There is a lot of historical chatter about the amount of swap space
>> > required.
>> > But for my question, I haven't seen discussion:
>> > What HAPPENS when the system flags "out of swap space".
>> > Does a process die? or does the system merely become very sluggish?
>> >
>>
>> Both, a process is killed and  whenever you're starting to use swap
>> space you should expect the system to become sluggish.
>
> I don't know that anything bad happens simply because you run out of
> swap. Processes are killed when the system is unable to find enough
> memory to carry on.
>
> For example if you have 4GB of RAM and 1GB of swap, and you leave 2GB
> on tmpfs, you may fill swap without even coming close to running out of
> memory. Another example is a very slow memory leak where running out of
> memory could happen a long time after running out of swap.
>
> There seems to be a common trend of allocating swap space that's much
> smaller than RAM. When you combine that with tmpfs use, I suspect it
> may have become much more common to run out of swap without
> consequences.
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-- 
Reed A. Cartwright, PhD
Barrett Honors Faculty
Assistant Professor of Genomics, Evolution, and Bioinformatics
School of Life Sciences
Center for Evolutionary Medicine and Informatics
The Biodesign Institute
Arizona State University
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