On Fri, Jul 03, 2020 at 01:32:12PM +0000, Zbigniew Jędrzejewski-Szmek wrote:
On Fri, Jul 03, 2020 at 09:18:42AM -0400, Colin Walters wrote:
> On Thu, Jul 2, 2020, at 11:53 AM, Zbigniew Jędrzejewski-Szmek wrote:
>
> > It would be great if we could fairly reliably boot with a read-only
> > root file system,
>
> Eh, just mount a tmpfs for /var, and an overlayfs for /etc (backed by a tmpfs).
I see that this thread is one massive communication failure on my part :(
I wrote about "booting successfully with a read-only file system", but I
see that I didn't say "... when the disk cannot be mounted rw because of
file system errors".
...but Colin did not say that. Neither tmpfs nor overlayfs (backed by
tmpfs) require any existing disk filesystems to be mounted read-write.
TBH, that was my first thought when I read your original e-mail: "why
would units fail if they only want to write non-persistent stuff to
an area that may perfectly well be mounted as tmpfs, just as /run
usually is?"
I thought it'd be clear from the context, but it's
clearly not. Anyway, while I'm a big fan of coreos and read-only-on-purpose,
I was writing about traditional systems in a read-only-by-accident scenario,
i.e. about the system behaving gracefully when the disk is ***unexpectedly***
read-only.
Zbyszek
PS. OK, I know I wrote about making it read-only on purpose using a
kernel commandline option, so really we're just pretending it was
unexpected for testing purposes, but you get what I mean I hope.
G'luck,
Peter
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