Re: Read-only FS, switch-off safety for raspberry pi

[Swift Griggs <swiftgriggs%gmail.com@localhost>]

On Fri, 17 May 2019, Mayuresh wrote:
> So I presume /var would be a ramdisk and root will be remounted ro or 
> something like that?

Yes, that's one scenario.

> I guess live-CD methods would require using build.sh, which is time 
> taking on pi.

No, I don't think that'd be needed. You'll probably just want to customize 
some of the rc startup scripts. The way it's typically done is that you'd 
take a portion of your RAM to convert to read-write areas you'll need, 
copy the files you care about off the read-only media, then overlay mount 
the ramdisk on top of the area that needs write access, like say /var/log 
or whatever.

> Is it possible to achieve the read-only mode by configuring a standard 
> installation image?

Yes, I think it should be. It'd be easier if you are able to tolerate the 
file system being read/write for a short period during the boot process, 
but I think it'd be possible even without that help.

If it were me, I'd begin by looking at the init scripts on a NetBSD liveCD 
that's already been created. You can learn their secrets then fix the 
parts you don't like or don't work in your case. The NetBSD installation 
media also uses a ramdisk etc...

-Swift