Re: [OSR-devel] Remounting New Root After Booting

[Marc G. <gr...@at...>]

On Thursday 11 October 2007 11:22:56 Gordan Bobic wrote:
> On Thu, 11 Oct 2007, Marc Grimme wrote:
> >>>>> So when the initrd gets the iscsi disk as scsi-disk all the rest
> >>>>> should be done automatically.
> >>>>
> >>>> Where is the template startup script for the initrd? A few things
> >>>> require a bit of manual intervention, because for some reason iscsid
> >>>> doesn't trigger loading of iscsi_tcp module which is required _before_
> >>>> iscsid loads.
> >>>
> >>> linuxrc.generic.sh is the main init-script.
> >>
> >> Aha! I see now what all the talk about iscsi-lib.sh was. This is what
> >> gets the parameters from the cluster.conf about the root source on iscsi
> >> stuff.
> >>
> >> But what can this do without the iscsi tools being included in the
> >> standard initrd?
> >>
> >> On a separte note, is this "old" iSCSI speciffic (i.e. pre-Open-iSCSI,
> >> as i see mentions of Cisco), or is it just a convenient "dump your iSCSI
> >> initialisation stuff here" script?
> >
> > You can ignore or use anything in iscsi-lib.sh. It is very old. And long
> > ago RHEL3 and I can't remember much of it. As it was only a "study" to
> > prove it works.
>
> Wow! This goes back as far as RHEL3? I'm impressed. :-)
It was started in 1999 or 2000 I don't rember exactly with some old SuSE 
version.
>
> >>>> And, obviously, I'd need to make all this happen before the normal
> >>>> boot process tries to mount the root disk.
> >>>
> >>> Do it before or right after scsi-start is called.
> >>
> >> I can't find any reference to "scsi-start". Where does this happen?
> >
> > It's scsi_start in linux.generic.sh Line 239.
>
> D'oh! What a difference an _ makes.
>
> I think the iSCSI stuff should be added before the dm_start stuff, which
> is just before the scsi_start.
yes. agreed.
>
> Right, that seems to have worked. Almost there. Now I get:
>
> Mounting LABEL=/ on /mnt/newroot..device not found error [FAILED]
hmm. That looks weired. Have a look at /var/log/comoonics-boot.log or send it 
and I can tell you more.
> Mounting /cdsl.local on /cluster/cdsl/3..no cdsldir found
> "/mnt/mewroot//cluster/cdsl"
> Could not mount cdsl /cdsl.local to /cluster/cdsl/3. Exiting
>
> Where does it get the LABEL=/ from? I'm pretty sure I didn't set any.
That's new for me as well.
>
> >>>> Or will specifying the iscsi stuff in cluster.conf make all this work?
> >>>> Given that the iscsi components weren't in the standard initrd, I'm
> >>>> not too convinced this will work (although there's a distinct
> >>>> possibility that this is totally unrelated and irrelevant in this
> >>>> case).
> >>>
> >>> Yes I agree. Make it work for you and we'll integrate it so it'll only
> >>> be called if iscsi is selected.
> >>
> >> LOL! I must say I'm not used to getting integrated into the development
> >> effort this quickly. Not that I don't mind. :-)
> >
> > We'll integrate it in preview and tag it as experimental. But as iscsi
> > integration is on our list but only in next major version we are happy to
> > use anything that is provided by others.
>
> It surprises me that the whole concept didn't start with iSCSI. How else
> can you provide a shared GFS root for a cluster? NBDs? Shared SCSI bus (2
> controllers in 2 machines with the drives shared on the chain)?
We started with SAN based on FibreChannel. Cause initially there was something 
we found quite nice which was called DMEP or DLOCKs or something that did the 
locking inside the SCSI-Protocol. But it didn't work out.

iSCSI wasn't there and gnbd either. There was only FibreChannel or a shared 
parallel scsi bus.

Marc

-- 
Gruss / Regards,

Marc Grimme
Phone: +49-89 452 3538-14
http://www.atix.de/               http://www.open-sharedroot.org/