[Libguestfs] guestfsd: error: mount_stub: /dev/sda2: No such file or directory

[Richard W.M. Jones]

On Sun, Mar 28, 2021 at 11:11:22PM +0200, Lukas Tribus wrote:
> Dear list,
> 
> 
> I'm trying to convert a Xen image to KVM, and it fails with (full
> verbose/debug trace below):
> 
> guestfsd: error: mount_stub: /dev/sda2: No such file or directory
> guestfsd: => mount (0x1) took 0.02 secs
> libguestfs: trace: v2v: mount = -1 (error)
> virt-v2v: error: mount: mount_stub: /dev/sda2: No such file or directory
> 
> >From guestfish I can see that my fstab file may be a little uncommon,
> /dev/xvda1 is swap and /dev/xvda2 is the ext3 root fs:
> 
> /dev/xvda1 none swap sw 0 0
> /dev/xvda2 / ext3 noatime,nodiratime,errors=remount-ro 0 1

Yes this is the problem.  Virt-v2v reads the fstab and assumes the
root filesystem must be on the second partition of the first disk
(ie. /dev/sda2 in the libguestfs namespace).  When it tries to mount
that it fails, and gives up.

Is Xen doing some weird partition table synthesis here?

> Could this be the reason virt-v2v gets confused and what would be the
> best way to fix this so that I can boot those old Xen guests in KVM?
> 
> The host is virt-v2v on Ubuntu 20.04, the guest I'm looking at is Ubuntu 18.04.

Since the guest already has virtio drivers installed and is relatively
recent, you could try simply copying the disk image across.  However
it's unlikely to boot without at least fixing /etc/fstab and probably
repairing and/or setting up a bootloader.  You can do these tasks
manually using “virt-rescue”.

Rich.

-- 
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