perfSONAR User Q&A and Other Discussion

["Whitworth, Luke" <>]

We are in the process of installing Pi’s around our campus with them talking back to a central Esmond DB doing simple latency tests as a mesh.

 

Left unchecked we could destroy an SD card in about a week with the frequent writes a testpoint does (logging and postgres) so we ended up having to make the Pi filesystem read only. 

 

What we did was create an Ansible playbook for the Pi’s that installed the Perfsonar-testpoint package from the repo, got the Pi to pull in published test definitions from a central URL, disabled almost all logging (redirected things to /dev/null, disabled rsyslog, limited journald ram usage etc.) to conserve RAM (as the overlayfs uses a tmpfs to store modifications) and then used raspi-config to enable the RO filesystem.  This now appears to be working quite happily for our use case.

 

I also have an ansible playbook that I can call to toggle the Pi’s back to read-write if I want to modify anything, then I can use the same playbook to put them back to read-only when I’m done.

 

I also put watchdog on them so that if any of the personar services stopped working it rebooted the Pi….mainly because early on before I got a handle on the RAM exhaustion they’d occasionally run out and then things would go a bit wobbly.  These days they sit at 800MB – 900MB free constantly (that’s on a 2GB RAM Pi).

 

Hope that’s some help,

 

Luke

 

From: <> On Behalf Of Michael Tiernan
Sent: 23 October 2020 15:24
To:
Subject: [perfsonar-user] Fwd: Re: Fwd: CI Engineering Brown Bag - Friday July 24th @ 2pm ET

 

A followup sort of question for those on the list.

 

On 7/23/20 12:52 PM, Jason Zurawski wrote:

 

This talk will focus on the experiences at University of Michigan installing and testing perfSONAR on non-traditional hardware platforms such as network hardware (routers) and Single Board Computers such as the Raspberry Pi.  We will also talk about the new perfSONAR S3 storage plugin and perfSONAR plugin development methodologies.

Has anyone worked on a SBC (Raspberry Pi is my current interest) "Target" for some of this testing?

I know there's a CPU muscle issue for doing all the heavy lifting PS would impose on a system so I wonder if anyone's thought of creating a simplified target that can respond to tests from a more powerful host?

Implementation example might be to facilitate "Work from home" operations where the "Company" could test links out to employee's endpoints for reliability and a modest standard of speed test. (As well as availability.)

Plant a simple SBC unit at the target's home and let it respond to test requests from a primary server.
(Yes, I know that this goes against the primary design goal of PS of "De-centralized" operations but it seems like a reasonable offshoot.)

It might even be able to do lightweight testing back against the single host but that would just be a plus in the overall design.

Thanks for your time.

-- 

 << MCT >> Michael C Tiernan

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