[CentOS] unable to recover software raid1 install

Wed Mar 18 01:02:00 UTC 2015
S.Tindall <tindall.satwth at brandxmail.com>

On Tue, 2015-03-17 at 20:20 -0400, S.Tindall wrote:
> On Tue, 2015-03-17 at 23:28 +0100, johan.vermeulen7 at telenet.be wrote:
> > 
> > on a Centos5 system installed with software raid I'm getting: 
> > 
> > raid1: raid set md127 active with 2 out of 2 mirrors 
> > 
> > md:.... autorun DONE 
> > 
> > md: Autodetecting RAID arrays 
> > 
> > md: autorun..... 
> > 
> > md : autorun DONE
> > 
> > trying to resume form /dev/md1
> 
> Hi Johan,
> 
> Your system is assembling md127, but is apparently expecting md1.
> 
> I suspect that you examined the raid1 from a previously working EL5
> system using a more-recent-than-EL5 LiveDVD, which assembled the raid1
> as md127 and wrote super-minor 127 to the raid1 (assuming ver. 0.90
> metadata). When started under EL5, it then assembled as md127, not md1,
> hence the problem.
> 
> If that is what happened, then boot the system with the same LiveDVD,
> stop the raid and then assemble it as md1 while updating the
> super-minor. (You might want to mount the installation and look at fstab
> and grub.conf while running the LiveDVD to verify that it is looking for
> md1).
> 
> For example (assuming md1 contained partitions sda1 and sdb1):
> 
> - (Boot using the LiveDVD)

I forgot (at least) one thing:

- (Stop md127-based swap > # swapoff -a )

> - (Unmount anything from md127 > # df -h)
> 
> - (Inactivate any VGs/LVs > # vgchange -an <VG> or lvchange -an <LV>)
> 
> # mdadm -S /dev/md127
> 
> # mdadm -A /dev/md1 -U super-minor /dev/sd[ab]1
> 
> Then shut down the LiveDVD and attempt to boot the system under EL5.
> 
> Steve
> 
> PS I don't watch EL5 boot very often/recently, so I might have misses
> something relevant in your post.
> 
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