Re: boot environment and /var/db/etcupdate ?

 
Van: Peter Jeremy <peterj@freebsd.org>
Datum: woensdag, 24 augustus 2022 10:46
Aan: John Kennedy <warlock@phouka.net>
CC: Ronald Klop <ronald-lists@klop.ws>, FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org>
Onderwerp: Re: boot environment and /var/db/etcupdate ?
> 
> On 2022-Aug-23 15:52:53 -0700, John Kennedy <warlock@phouka.net> wrote:
> >On Tue, Aug 23, 2022 at 04:02:48PM +0200, Ronald Klop wrote:
> >> Hi,
> >>
> >> I'm running the super duper boot environment using ZFS. [1]
> >>
> >> I have /var and /usr/local as separate datasets. These do not change when I upgrade the OS and that keeps the backups a lot smaller as the backup sees a new BE as a new dataset and fully zfs sends all the data again.
> >>
> >> But when I rollback /var/db/etcupdate is not in sync with / anymore.
> >> And /var/db/ports and /var/db/pkg should be kept in sync with /usr/local. But I do not need to rollback these if I need to go back to the previous BE.
> 
> Looking in /var, the only thing I can see that needs to track the BE
> is /var/db/etcupdate - everything else should preferentially be
> outside the BE (and having things like e.g. /var/mail in the BE will
> cause problems if you rollback the BE).
> 
> /usr/local and /var/db/pkg need to track to prevent package installation
> metadata getting out of step with the actual installed packages.
> 
> >  For my part, /var/db/pkg is mostly just a reference to my local
> >poudriere package stash and is relevant to the BE (but pretty stagnant
> >unless I'm changing major versions between 12/13/14).  On my system,
> >/var/db is part of /.
> 
> Several database ports default to putting their data under /var/db so
> having that in a BE is likely to cause problems if you rollback.
> 
> >  I'd be a little leery of having /usr/local decoupled from the BE,
> >but that's mostly worried about things like kernel drivers that would
> >get out of sync with the kernel in the BE.
> 
> Kernel driver ports should all be in /boot/modules, not /usr/local (this
> does mean that rolling back a BE will cause problems with the metadata
> associated with those ports, but typically there are relatively few
> such ports).  I don't believe there are any other ports that are
> tightly bound to the actual running kernel (though sysutils/lsof comes
> close).
> 
> A downside of putting /usr/local in the BE is that another large
> collection of ports default to storing their data under /usr/local
> and that should be decoupled from BEs.
> 
> Overall, I don't believe there's a one-size-fits-all solution to
> identifying what should be part of the BE.  If you are using BEs
> to switch between major versions, it probably does make sense to
> include /usr/local in the BE - but then you need to extricate all
> the application data that needs to not be rolled back.
> 
> -- 
> Peter Jeremy
> 
> 
> 
>  


Hi,

I agree. I think the structure of /var is a bit inconsistent with the recommendation from the BootEnvirtonments wiki page [1] and bsdinstall [2].
AFAIS /var/db/pkg and /var/db/ports could better be in something like /usr/local/var/db. /var/db/portsnap has similar issues to stay in sync with /usr/ports.

And when I do a major upgrade of pkgs I find it ok to make a separate snapshot of /usr/local. I use BEs primarily to have predictable OS upgrades.

You are right the one size fits all is a hard one. And the current structure of /var makes it hard to customize also. ;-)

Regards,
Ronald.

[1] https://wiki.freebsd.org/BootEnvironments
[2] https://www.freebsd.org/cgi/man.cgi?bsdinstall(8)