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* kvm on Ubuntu 8.04 running windows xp sp3: corrupts file system on shutdown?
@ 2009-07-02 15:50 Jon Watte
  2009-07-02 15:53 ` Yaniv Kaul
  0 siblings, 1 reply; 5+ messages in thread
From: Jon Watte @ 2009-07-02 15:50 UTC (permalink / raw)
  To: kvm

I'm attempting to set up a Windows XP virtual machine using KVM
running on 8.04 LTS x64 or a Core 2 Duo (6550). I have updated all
installed packages to the latest available as of a week ago. This is
KVM version 0.9.1 (kvm-62) on a kernel version 2.6.24-22-server.

I'm creating a 20 GB hard disk image with qemu-img, (on a file system
that is managed by LVM, and in turn backed by a md0 soft mirror) and
then starting the VM as follows:

#!/bin/sh
cd /var/kvm/wxp_build
kvm -m 1024M \
-hda wxp_build.img \
-usb -usbdevice tablet \
-vnc :1 \
-localtime \
-net nic,model=virtio -net user \
-redir tcp:5555::5555 \
-daemonize \
$*

When I install, I pass "-cdrom ../cdrom/wxp_sp3_installer.iso -boot d"
to boot from the Windows install CD. The reboot as part of the install
does not take down the VM, and does not cause any problems.

I can go through install just fine. I format the 20 GB image as NTFS,
using slow format (not quick format).

I can download and install other things fine, too. However, when I
shut down the virtual machine (using the Windows Shut Down command),
and wait for the VNC connection to end, the (virtual) hard disk seems
to get corrupt. When I boot again, one of three things happen:

1) The boot fails, because some necessary file has gotten corrupted.

2) The boot succeeds, but when I attempt to run something that I
installed that worked fine before the shutdown, it doesn't work after
the shutdown, with missing DLL errors or similar.

3) The boot kicks into CHKDSK, which finds tons and tons of NTFS file
system corruption on the virtual hard disk image.

I've tried with both qcow2 and raw disk images, with the same results.

To my mind, it behaves as if the KVM process decides to exit as soon
as the BIOS power-off signal comes, but the process keeps the hard
disk write buffer in user-mode RAM, rather than immediately having
passed it on to the kernel. Thus, when the process exits, whatever was
buffered will not be committed to disk, and badness ensues. I'm not
sure at all that this is what actually happens, but that's what it
feels like. It could be some other kind of image corruption, too, but
it's clearly related to actually powering off the virtual machine.

Btw: the same corruption happens if I kill the KVM while it's running
(rather than do a "clean" shut-down). It's slightly more
understandable under that situation, but not really -- NTFS is a
journaling file system, and never has those corruption issues on my
"native" Windows machines, even during power fail.

So... does anyone have a clue what could be causing this, and what I
can do to fix it?



--
Americans might object: there is no way we would sacrifice our living
standards for the benefit of people in the rest of the world.
Nevertheless, whether we get there willingly or not, we shall soon
have lower consumption rates, because our present rates are
unsustainable.

^ permalink raw reply	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2009-07-02 20:08 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2009-07-02 15:50 kvm on Ubuntu 8.04 running windows xp sp3: corrupts file system on shutdown? Jon Watte
2009-07-02 15:53 ` Yaniv Kaul
2009-07-02 16:15   ` Dustin Kirkland
2009-07-02 20:08     ` Jon Watte
2009-07-02 16:40   ` Jon Watte

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