[vm-bhyve] shutting down VMs and kern.init_shutdown_timeout

[Adam]

On Mon, Apr 29, 2019 at 3:24 AM Victor Sudakov <vas at mpeks.tomsk.su> wrote:

> Patrick M. Hausen wrote:
> >
> > > Am 28.04.2019 um 06:41 schrieb Victor Sudakov <vas at mpeks.tomsk.su>:
> > > "if the /etc/rc.shutdown does not terminate within 120 seconds, init
> will
> > > terminate it.  The timeout can be configured via the sysctl variable
> > > kern.init_shutdown_timeout.“
>
>
> > What’s keeping you from increasing that timeout for your
> > particular requirements?
>
> Is that really necessary? Am I correct assuming that any VM is supposed
> to shut down within 2 minutes or else the bhyve processes will be
> killed? Or is this kern.init_shutdown_timeout only about the rc.shutdown
> script itself and not its children?
>

FreeBSD is tuned as a general purpose server OS.  If you find the defaults
don't meet your needs, you can change them.  That's why tunables exist.


> > IMHO 2 minutes are a reasonable
> > default for a system that does not run hypervisor VMs -
> > which is probably the vast majority.
> >
> > Anyone with the knowledge to implement a virtualized
> > environment
>
> The lack of information about this caveat in
> https://wiki.freebsd.org/bhyve, man vm-bhyve,
>
> https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/virtualization-host-bhyve.html
> and other sources suggests that this particular knowledge may be
> limited. Other hypervisors (non-bhyve) probably wait for all VMs to stop.
>

RH implemented this relatively recently.

https://bugzilla.redhat.com/show_bug.cgi?id=1334982

> can simply set that to a more suitable value,
> > can’t he/she?
>
> Yes if they know about it. There should be a warning somewhere in the
> documentation if we want to be serious about FreeBSD as a hypervisor.
>
> Or better still, a warning that rcshutdown_timeout (if set) and
> kern.init_shutdown_timeout can be too low when running vm-bhyve and
> such is desirable.
>

Why don't you simply write a wrapper script which calls shutdown after
shutting down guests?  I doubt many admins on any hypervisor are
gratuitously calling shutdown on host with important guests running.

-- 
Adam