Bug#1027915: systemd requires /run to be mounted with a minimum size of 20MB

[Helge Deller]

Package: systemd
Version: 252.4-1
Severity: important

Systemd mounts the /run tmpfs filesystem at bootup with a given/calculated size (I assume ~ 10% of free memory?).
The problem is, that this size needs to be at least 16MB (probaly better 20MB), because otherwise
systemd refuses to reload when exiting emergency mode.

I noticed that problem on my hppa machine.
It has 160MB RAM (which is not much of course).
Anyway, on this machine systemd had mounted /run at bootup with ~15MB:
tmpfs on /run type tmpfs (rw,nosuid,nodev,noexec,relatime,size=14812k,mode=755)
During bootup the system failed to mount some other drive and thus fell into emergency mode.
I then entered the password to enter the shell, mounted the drive and exited the shell to
continue with normal bootup, but then systemd reported:
...
Reloading system manager configuration
Failed to reload daemon: Refusing to reload, not enough space available on /run/systemd. Currently, 14.2M are free, but a safety buffer of 16.0M is enforced.
Starting default.target
...
My suggestion:
Please check that the /run mountpoint is mounted with at least 20MB, independend
of the installed RAM memory in the machine...

Thanks!
Helge