Thanks Laurent for the detailed explanations. We did a bootup speed
comparison between S6 and systemd. S6 is able to boot up slightly faster
than systemd. Actual result is 4-4.5% faster but we were expecting
something near to 20%.
Ours is a bit complex setup with more than 140 services (includes a lot of
long run services and a lot of dependencies). The main advantage in systemd
is, it starts many critical processes very quickly since it has no
dependency to logging services. We collect the logs from journalctl and
store it in log files. Whereas in S6, the critical services start up is a
bit delayed since it has to depend on logging services which in turn
depends on other services (responsible for backing up the previous logs).
Thank you for these numbers! Indeed they confirm my intuition: booting
via s6 is a little faster than systemd, but nothing extraordinary,
because s6-rc emphasizes reliability over speed.
Your critical services may be slightly delayed, but you have the
guarantee that you will not lose logs - whereas with systemd, if a piece
of your logging system fails to start, your critical services may
already
have produced some data that will vanish into the aether. Whether or not
that's an acceptable risk is up to you.
--
Laurent
