Ondemand server system limits question

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1

We had a first class on our OnDemand server last Tuesday which resulted in about 30 users simultaneously logging into the server. It did not go that well, and dmesg shows the following:
[Tue May 12 11:55:25 2020] Pid 8081(ps) over core_pipe_limit
[Tue May 12 11:55:25 2020] Skipping core dump

That gave us a hint to change the core_pipe_limit to unlimited from the default of 4, in the sysctl.conf file. We increased the maximum available number of file handles from 6000 to 60000.

That seems to have taken care of this issue as today the class is not complaining (yet).

Since I haven’t seen any notion of these settings in the docs, I am wondering if we just happened to have them too low from the start, or, what other people do when they set up the OOD server.

Thanks,
MC

2

OSC runs RHEL 7.x for our systems and looks like kernel.core_pipe_limit is 0 for unlimited. This is not a value we changed, maybe a default provided by RedHat. The value for fs.file-max seems to default to 6520448 from RedHat. If you are not running RedHat but instead running CentOS then you maybe running into some poor defaults imposed by CentOS or lack of good defaults you might otherwise get from RedHat.

3

Thanks Trey, yes, we run CentOS. I’ll share this with our admins to see what they have to say about the CentOS defaults.

I am wondering if it may be useful to include this info, or warning, to the OOD install docs.

MC