[systemd-devel] early mounts in systemd

[Lennart Poettering]

On Fr, 30.04.21 15:14, Kenneth Porter (shiva at sewingwitch.com) wrote:

> --On Friday, April 30, 2021 11:39 AM -0400 Rick Winscot
> <rick.winscot at gmail.com> wrote:
>
> > Early in the project it was decided to make the rootfs read-only... in an
> > effort to improve durability in environments where power fluctuations
> > might cause problems on the eMMC. At the same time, making logging (e.g.
> > /var) persistent for debugging was added to requirements. Persistent
> > storage would be achieved by mounting /var to a separate partition that is
> > read-write.
>
> Does /etc need to be read-only? On my last server I decided to make /usr
> read-only but root is writable and /var is part of that. I put /home on its
> own partition.

I think making /usr read-only makes a ton of sense.

The way I see it, besides the traditional Linux scheme where the whole
fs is writable the following two scenarios make the most sense, and
are what I personally intend to support in systemd very well:

1. root fs writable, /var/ part of it, but /usr/ separate and
   read-only/immutable.

2. rootfs read-only/immutable, /usr/ part of it, but /var/ separate
   and writable.

The main difference I that in the second case the configuration is
immutable too, while the firt case allows it to be changed locally.

Lennart

--
Lennart Poettering, Berlin