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From Stephan Seitz <s.se...@secretresearchfacility.com>
Subject Re: Access root disk after botched upgrade
Date Sun, 21 Jun 2015 11:14:50 GMT
Hi,

on XenServer I'ld expect your SR containing *.vhd files. You could use
the cli "xe" command to determine which file is attached. Maybe this
info can also be seen in the gui.

Here's a short walkthrough, how to access vhd files:
http://wiki.xen.org/wiki/Mounting_a_.vhd_disk_image_using_blktap/tapdisk

If your vhd file contains partitions, you could do a
kpartx -a /dev/xen/....
to get
/dev/mapper/blktap0p[0....n]

Depending on your guest OS, e.g. If there's LVM or dm-crypt etc...
inside the following steps vary.

Just use standard linux tools to mount / pvscan / cryptsetup / ...
the /dev/mapper/blktap... partitions.

With additional bind-mounts of /sys, /proc, /run, /dev, /dev/pts you
should be able to chroot into the filesystem and perform the necessary
tasks.

Just as a note: Be careful, to do this only exclusively, say with the
respective VMs powered-off. Also, double check to umount / pvchange
-n / ... every layer you've built. Also kpartx -d the partitions and
unmap the blktap before trying to boot the VM.

Good luck!

- Stephan


Am Sonntag, den 21.06.2015, 12:43 +0200 schrieb France:
> Hi,
> 
> after upgrading Ubuntu Linux, the system does not boot, probably because of wrong grub
config format:
> (           errorInfo: [Traceback (most recent call last):,   File "/usr/bin/pygrub",
line 808, in ?,     fs = fsimage.open(file, part_offs[0], bootfsoptions), IndexError: list
index out of range, ])
> 
> How can I get access to disk of this VM, to fix the grub file by hand and try to restart
it?
> I have CS 4.3 on XS 6.0.2 with ISCSI disk for virtual instances.
> 
> Tnx.
> France.


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