[Engine-devel] [vdsm] [ATTENTION] vdsm-bootstrap/host deployment (pre-3.2)

[Alon Bar-Lev]

----- Original Message -----
> From: "Dan Kenigsberg" <danken at redhat.com>
> To: "Alon Bar-Lev" <alonbl at redhat.com>
> Cc: "VDSM Project Development" <vdsm-devel at lists.fedorahosted.org>, "engine-devel" <engine-devel at ovirt.org>, "users"
> <users at ovirt.org>
> Sent: Wednesday, November 28, 2012 10:39:42 PM
> Subject: Re: [vdsm] [ATTENTION] vdsm-bootstrap/host deployment (pre-3.2)
> 
> On Wed, Nov 28, 2012 at 02:57:17PM -0500, Alon Bar-Lev wrote:
> > 
> > > > No... we need it as compatibility with older engines...
> > > > We keep minimum changes there for legacy, until end-of-life.
> > > 
> > > Is there an EoL statement for oVirt-3.1?
> > > We can make sure that oVirt-3.2's vdsm installs properly with
> > > ovirt-3.1's vdsm-bootstrap, or even require that Engine must be
> > > upgraded
> > > to ovirt-3.2 before upgrading any of the hosts. Is it too harsh
> > > to
> > > our
> > > vast install base?  users at ovirt.org, please chime in!
> > >
> > 
> > I tried to find such, but the more I dig I find that we need to
> > support old legacy.
> 
> Why, exactly? Fedora gives no such guarntees (heck, I'm stuck with an
> unupgradable F16). Should we be any better than our (currently
> single)
> platform?

We should start and detach from specific distro procedures.

> 
> > > > > > 
> > > > > >  * legacy-removed: change machine width core file
> > > > > >   # echo /var/lib/vdsm/core > /proc/sys/kernel/core_pattern
> > > > > 
> > > > > Yeah, qemu-kvm and libvirtd are much more stable than in the
> > > > > old
> > > > > days,
> > > > > but wouldn't we want to keep a means to collect the corpses
> > > > > of
> > > > > dead
> > > > > processes from hypervisors? It has helped us nail down nasty
> > > > > bugs,
> > > > > even
> > > > > in Python.
> > > > 
> > > > It does not mean it should be at /var/lib/vdsm ... :)
> > > 
> > > I don't get the joke :-(. If you mind the location, we can think
> > > of
> > > somewhere else to put the core dumps. Would it be hard to
> > > reinstate a
> > > parallel feature in otopi?
> > 
> > I usually do not make any jokes...
> > A global system setting should not go into package specific
> > location.
> > Usually core dumps are off by default, I like this approach as
> > unattended system may fast consume all disk space because of
> > dumps.
> 
> If a host fills up with dumps so quickly, it's a sign that it should
> not
> be used for production, and that someone should look into the cores.
> (P.S. we have a logrotate rule for them in vdsm)

There should be a vdsm-debug-aids (or similar) to perform such changes.
Again, I don't think vdsm should (by default) modify any system width parameter such as this.
But I will happy to hear more views.

> 
> > If sysadmin manually enables dumps, he may do this at a location of
> > his own choice.
> 
> Note that we've just swapped hats: you're arguing for letting a local
> admin log in and mess with system configuration, and I'm for keeping
> a
> centralized feature for storing and collecting core dumps.

As problems like crashes are investigated per case and reproduction scenario.
But again, I may be wrong and we should have VDSM API command to start/stop storing dumps and manage this via its master...

> 
> > If we want to automatically enable dumps I guess it should go to
> > /var/lib/core or similar.
>