Re: [Libguestfs] virt-resize problem for Windows 2003
On Wed, Nov 06, 2013 at 10:58:06AM +0800, Xinglong Wu wrote:
Hi,
I'm using virt-resize to expand the primary partition (C:) in a
Windows 2003 image. The command works fine but after expanding, when I boot
into Windows 2003, all the other partitions (D:, E:, and F:) are lost.
I can see why this would happen.
In the Windows registry, Windows stores drive letter mappings using a
(basically crazy) system using the partition offset. It is described here:
http://www.goodells.net/multiboot/partsigs.shtml
"How does Windows XP remember drive letters?"
We implement this in libguestfs:
https://github.com/libguestfs/libguestfs/blob/aee6fc4863c170d08e572dbdcfc...
Virt-resize moves partitions around, so of course the partition offset
changes and we don't update the registry to reflect this. As a result
Windows cannot find the D:/E:/... partitions any longer. (I believe
the C: drive probably works a bit differently, so the C: drive isn't
"lost").
Anyway, we could conceivably fix up the Registry in virt-resize. You
would need to file an RFE bug:
http://libguestfs.org/guestfs-faq.1.html#how-do-i-propose-a-feature
Patches would be even better, since I don't know when we'd get around
to fixing such a complex corner-case.
After using the disk management tool within Windows 2003, I can
re-label
the above three partitions and all the files are still there. But it is
really annoying because every time you have to do some work by hand after
expanding the disk size. As below is the details:
Host OS: RHEL6.3
libguestfs: libguestfs-1.16.19-1.el6.x86_64
libguestfs-tools-c-1.16.19-1.el6.x86_64
libguestfs-winsupport-1.0-7.el6.x86_64
It won't fix your problem, but there is a newer version of libguestfs
available for RHEL 6 users:
https://www.redhat.com/archives/libguestfs/2013-May/msg00100.html
Guest OS partitions:
C: /dev/sda1 primary
D: /dev/sda5 logical
E: /dev/sda6 logical
F: /dev/sda7 logical
Also, if I use virt-resize on logical partitions (i.e., D: E: or F:), the
command runs fine but logical partitions don't actually expand. Exactly the
same problem as descripted above shows up, and now, these logical
partitions don't even change their sizes. Any suggestions?
Virt-resize cannot resize individual logical partitions. It can only
resize the extended partition that contains the logical partitions. See:
http://libguestfs.org/virt-resize.1.html#logical-partitions
This is not expected to change any time soon.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into KVM guests.
http://libguestfs.org/virt-v2v