Low disk space on a worker can have a catastrophic effect on builds. For example, this a-quick had plenty of failures because one worker had low space on disk: https://autobuilder.yoctoproject.org/typhoon/#/builders/85/builds/2526 What happens is that the build fails but as the worker is still available, it will be selected to run the next build which fails for the same reason and so n... Disk space checks need to be improved to avoid this situation.
I suspect we only monitor the space on one disk and we need to monitor it on all key partitions
Disk space code is here: https://git.yoctoproject.org/yocto-autobuilder2/tree/builders.py#n68
Looking at a recently failure, it is the main disk filling up: https://autobuilder.yoctoproject.org/typhoon/#/builders/79/builds/7021/steps/14/logs/warnings although: https://autobuilder.yoctoproject.org/typhoon/#/builders/85/builds/2526/steps/13/logs/warnings shows it was /tmp that filled up. I've pushed https://git.yoctoproject.org/yocto-autobuilder2/commit/?id=d809e29a23d5614d8873c3f5f1fb7293da96cdd0 which should help and make it easier to add other mount points.
I opened https://bugzilla.yoctoproject.org/show_bug.cgi?id=15569 for further work, closing this one as the multiple dirs issue has been fixed