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

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

On Thursday 11 October 2007 10:45:58 Gordan Bobic wrote:
> On Thu, 11 Oct 2007, Marc Grimme wrote:
> >>>> I have iscsi loading and letting me see the relevant shares. I can
> >>>> mount them. But how do I then remount root to a GFS share on iSCSI?
> >>>>
> >>>> I tried:
> >>>>
> >>>> mount -t gfs -o lockproto=lock_nolock,remount /dev/sdb2 /
> >>>
> >>> Normally the bootimage itself should take over the mounting. You should
> >>> not bother with it. I don't know if you can easily remout a gfs with
> >>> changing the lockproto. So as you don't get any errors and it didn't do
> >>> anything it does not work.
> >>>
> >>> But again, normally the initrd mounts the gfs filesystem you specified
> >>> within you cluster.conf. We didn't test with raw-devices we are always
> >>> using LVM/CLVM lvs for doing the mount.
> >>
> >> I'm not convinced the problem is in the lack of (C)LVM.
> >
> > Me either and I didn't say so. I just more or less said it is best
> > practice to use (C)LVM and yes it is not required. But we don't test
> > without so I don't know if it really works although it should.
>
> I must say I'm not a fan of LVM, clustered or otherwise. It seems like yet
> another technology to solve a problem that doesn't exist - or at least
> shouldn't with even a small amount of forward planning. And it's made
> doubly redudant when you consider that modern RAID, both hardware and
> Linux software, allows transparent on-line growing of RAID by adding
> additional disks/controllers.
>
> >>> 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.
>
> >> 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.
>
> >> 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.
>
> I must say that I'm now thinking that the idea of configuring iscsi stuff
> via cluster.conf is kind of neat. But I'll get it running the "manual" way
> first, as I think it'll be easier to debug until I get it running.
>
> Now if only I can figure out what you meant by scsi-start - grep finds
> nothing. :-(
see above.
>
> Gordan
>
> P.S.
>
> Any chance we can get the mailing list to set the ReplyTo header to go
> back to the list?
>
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-- 
Gruss / Regards,

Marc Grimme
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http://www.atix.de/               http://www.open-sharedroot.org/

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