Re: Setting up /boot when it is not a separate partition

[Fabian Deutsch <fdeutsch redhat com>]

On Thu, Aug 13, 2015 at 3:31 PM, Colin Walters <walters verbum org> wrote:
> On Thu, Aug 13, 2015, at 05:16 AM, Fabian Deutsch wrote:
> > On Tue, Aug 11, 2015 at 11:03 PM, Colin Walters <walters verbum org> wrote:
> > > On Wed, Aug 5, 2015, at 12:12 PM, Chris Murphy wrote:
> > >
> > > > I'm noticing the initramfs for Fedora Atomic installation is
> > > > nohostonly, so they are each ~41MB rather than the 18MB I see on
> > > > Fedora Server/Workstation. Is this intentional?
> > >
> > > Currently yes - the initramfs is assembled server side.  That could change,
> > > but it's not high priority for me right now at least.
> >
> > Let me note that client side initramfs generation is needed to support
> > multipath devices reliably.
>
> Why is that?  This is just config data, right?  That should be able to go on the kernel commandline.

No, it's not just config data.

Two cases:
1. Some hardware requires to set special directives in the
multipath.conf to setup their handlers correctly
2. To be able to boot from a multipath device reliably, the wwid must
be known up on device initialisation (happens in initramfs)

1. can not be fixed by kernel commandline arguments - alua is a case
where you need to modify the configuration file (See also [0] [1] [2])
2. can partially be addressed by kernel commandline arguments
(mpath.wwid=<wwid>) but they can be quite long, and sometimes you
might need to add more than one wwid.


- fabian

[0] https://bugzilla.redhat.com/show_bug.cgi?id=1235965
[1] https://bugzilla.redhat.com/show_bug.cgi?id=1204212#c6
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1002862#c55