starting Fedora Server SIG

[Jeremy Katz]

On Fri, 2008-11-14 at 17:10 -0500, Seth Vidal wrote:
> On Fri, 14 Nov 2008, Jeremy Katz wrote:
> > Also, there's this weird "running daemons are bad" mentality which I'm
> > not really sure what the right way to approach is.  But it's one that
> > I'm not sure how true it is in our current world of increasingly moving
> > functionality out of the kernel and into userspace in which case you
> > have to have something running in addition to the kernel.
> >
> > Maybe to try some examples -- irqbalance is a daemon and not in the
> > kernel anymore[1], does that make it "not useful"?  Or for another side,
> > various kernel threads are really just daemons... maybe we shouldn't run
> > them either?
>
> if you replace useful with necessary in his argument I think it ends up 
> making more sense.

I'm really not convinced that it does, though.  Because it's really not
necessary to run anything at all.  We could stick everything hard-coded
into the kernel and be done with it.  You wouldn't have a very useful
system at the end though.  At least, not for any things other than the
explicit purpose you built your kernel for.  

> If the daemon is not NECESSARY for the task it is fulfilling then why have 
> it running?

It's NECESSARY because the task is more complex than just one need and
so the design of the system includes a running daemon.  Just like
there's a separate kernel thread for some network devices now.  The only
difference is that the "daemon" is in the kernel and you have no real
control over it.

> And I think you do understand quite well the rule that any thing that is 
> not necessary to the functioning of a server should be off.

I'm not hung up with this "daemons are bad.  turn them all off"
mentality, though.  And so I look at "thing that is not necessary to the
functioning of a server" not as system things like dbus or hal or
NetworkManager or irqbalance or ...  If the implementation is that these
are daemons, then hey, so be it.  The upside is that it means that they
*can* have functionality to deal with dynamic environments.  Which
actually are a concern at some point for most machines which don't end
up in a closet with the door dry-walled shut.

For "things that is not necessary to the functioning of a server", I
would look at things like cups on a machine that's never going to have a
need to print[1], or httpd on a machine that's not serving http.

Jeremy

[1] Well, arguably, we should start the printing bits on demand if
you're not running an actual print server.  But that's another
discussion entirely :)