Date: Mon, 12 Sep 2022 16:05:53 +0200 (CEST) From: freebsd@oldach.net (Helge Oldach) To: Cy.Schubert@cschubert.com Cc: cy@FreeBSD.org, src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: Re: git: 3418c14040f2 - stable/13 - libexec/rc: Add var_run rc script Message-ID: <202209121405.28CE5r8m053976@nuc.oldach.net> In-Reply-To: <20220912131715.06DE9171@slippy.cwsent.com> from Cy Schubert at "12 Sep 2022 06:17:14"
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Cy Schubert wrote on Mon, 12 Sep 2022 15:17:14 +0200 (CEST): > In message <202209120716.28C7Gjd2091559@nuc.oldach.net>, Helge Oldach > writes: > > Cy Schubert wrote on Mon, 12 Sep 2022 02:41:14 +0200 (CEST): > > > libexec/rc: Add var_run rc script > > > > > > Users with a tmpfs /var/run will lose the directory tree state of > > > /var/run at reboot. This rc script will optionally (by default) > > > capture the state of the directory structure in /var/run prior to > > > shutdown and recreate it at system boot. > > > > > > Alternatively a user can save the state of the /var/run directories > > > manually using service var_run save and disable the autosaving of > > > /var/run state using the var_run_autosave variable, for those > > > paranoid SSD users. > > > > I'm afraid this logic does not rhyme well with a common scenario: Firing > > up a tmpfs based /var by simply booting with a non-writeable /var which > > will trigger /etc/rc.d/var to create, mount and populate a tmpfs based > > /var. This is the classic diskless scenario. > > > > The concern is that var_run by default saves the var_run created mtree > > on exactly this tmpfs based /var (as /var/db/mtree/BSD.var-run.mtree) so > > it will be gone with the next reboot. This will void the var_run logic > > for the default case. > > > > I would suggest to document that tweaking var_run_mtree appropriately is > > necessary for such scenarios. > > > > Furthermore, I propose to consider extending the scope of var_run from > > /var/run to the whole of /var, which would be sensible in certain > > diskless cases as well. > > Your scenario is outside of the scope of this change. This change was > designed to support those who use a standard /var with a tmpfs /var/run, > similar to Red Hat Linux support of /var/run. Indeed. I am trying to widen the scope by considering what /etc/rc.d/var does and put /etc/rc.d/var_run in perspective. With current defaults, var_run will not deliver as expected for the case of a volatile /var. In an abstract sense, /etc/rc.d/var and /etc/rc.d/var_run somewhat contradict. > Regarding diskless scenarios, my experience with SunOS 4.1.3 in a corporate I was more thinking about embedded scenarios where the root fs is readonly for a reason. Kind regards Helge
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