[dm-devel] Re: DM multipath and partitions

christophe varoqui christophe.varoqui at free.fr
Thu Sep 9 20:46:16 UTC 2004


Now that is interesting :)

I obviously want the tools to support system-on-SAN, but I never got the
time to do the testing.

What I would try is :
1) add multipath & kpartx tools to you initrd skeleton
2) launch multipath at the end of /linuxrc or whatever script gets
exec'ed in the ramdisk. Pass the multipath output to "kpartx -a"
(mangling needed here)
3) regenerate the initrd.gz
4) boot the kernel with root="label=/" param

Please keep the dm-devel list and me informed about your progress.
If anyone on the list has insights about this process, please voice up.

regards,
cvaroqui
Le jeu 09/09/2004 à 19:14, Andy a écrit :
> On Thu, Sep 09, 2004 at 12:13:33AM +0200, christophe varoqui wrote:
> > > 
> > > Is there any way to get multipath to multipath each partition (or even just
> > > the first one?
> > > 
> > > i.e. dm-0 would be sdb1
> > >      dm-1 would be sdb2
> > > 
> > the multipath-tools won't do the above : they do not care about
> > partitions. The multipath target is applied to the whole disk, then,
> > upon bdev (dm-0) appearence in the system, an hotplug event can get
> > trapped by a tool like kpartx that will layer linear maps upon dm-0 ...
> > giving you what you describe here :
> > 
> > > or dm-0p0 and dm-0p1.
> > > 
> What I would like to do is to boot off the SAN and have a multipathed root.
> AFAIK, you need to have a partitioned disk to boot off of.  Up till now,
> I've been using multipathing for data/programs disks.  I can use the whole
> disk and not use partitions.  But, to boot I need partitions.  It's not a
> must do, but something that would be really nice to be able to do.  Any
> ideas?
> 
> Andy




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