Bugs item #2490866, was opened at 2009-01-07 06:10 Message generated for change (Comment added) made by danv You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=893831&aid=2490866&group_id=180599 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: qemu Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Adrian Bridgett (abridgett) Assigned to: Nobody/Anonymous (nobody) Summary: repeatable corruption with qcow2 on kvm-79 Initial Comment: Creating a qcow2 image, mkfs.ext3, sometimes mounting it would fail immediately, but in all cases it would corrupt (overwritten with zeros) after starting up backuppc on it. This is KVM-79 on a Debian lenny host and guest. This occured using virtio or not. Swapping to a raw file or LV worked flawlessly. I've tested the box with memtest and I don't have issues elsewhere but I've seen corruptions on other images. host and guest are both 2.6.26-1-adm64 kernel (debian lenny) I'm running 32-bit userspace everywhere. Dual core Intel Core2 E6300. I see KVM-81 has "improve qcow2 data integrity with cache=writethrough" which _might_ be what I'm hitting - but I can't find more details about this to check (and backport patch to debian package or wait for newer debian package). thanks. ---------------------------------------------------------------------- Comment By: Daniel van Vugt (danv) Date: 2009-01-21 15:47 Message: As the original problem is resolved, it's description now inaccurate, and my problem is ongoing, please close this bug. I will open a new one. ---------------------------------------------------------------------- Comment By: Daniel van Vugt (danv) Date: 2009-01-15 10:47 Message: Reproduced qcow2 corruption again, using kvm-83 now. Same steps as before. ---------------------------------------------------------------------- Comment By: Daniel van Vugt (danv) Date: 2009-01-13 20:50 Message: My problem is kvm-82 vanilla, compiled with no special options. It happens consistently with kvm-82, but is not necessarily new to kvm-82 because I haven't used these images extensively with prior kvm releases. No, I do not do anything dangerous like run multiple guests with the same image or manage snapshots while the guest is up (only at pre-boot, when stopped). To reproduce repeatedly in the two cases I've seen it recently: Case A: Windows Server 2003 (standard and enterprise) x86: 1. Boot guest (previously created under kvm-81) 2. Let Windows detect the new hardware (kvm-82 changes) 3. Reboot as instructed 4. Windows guest continues to work after multiple reboots and the console shows snapshots intact 5. Shut down the Windows guest properly 6. Image is now invalid as soon as qemu(kvm) exits (not recognizable as qcow2, not bootable and no snapshots reported by qemu-img info) Case B: Windows 7 beta x86 1. Installed under kvm-82 2. Boot guest 3. Shut down guest 4. Image is now invalid as described. This is a very serious problem. Thought it sounds like a new separate bug may be required... ---------------------------------------------------------------------- Comment By: Laszlo Dvornik (ldvornik) Date: 2009-01-13 19:23 Message: I narrowed down my problem to one Fedora patch, which include in Debian too, but not in vanilla kvm, so vanilla kvm isn't effected. The Fedora patch: http://cvs.fedoraproject.org/viewvc/rpms/kvm/devel/kvm-62-block-rw-range-check.patch?revision=1.7&view=markup I removed the CVE-2008-0928-fedora.patch from the debian source package and recompiled it, the partitioning problem solved. Fedora bugzilla entry: https://bugzilla.redhat.com/show_bug.cgi?id=433560 A question. Is this vulnerability confirmed by qemu devels or why only distributions fixed this? Their fix seems to cause problems with qcow2, qcow, vmdk formats. The patch works well last in debian before 79+dfsg-3, when they started to use Fedora's updated patch. Perhaps the packagers modified the patch for newer kvms badly. Debian kvm git repo's commit: http://git.debian.org/?p=collab-maint/kvm.git;a=commitdiff;h=bae731aae2195651090517903f338635117fbd36 ---------------------------------------------------------------------- Comment By: Dor Laor (thekozmo) Date: 2009-01-13 17:23 Message: danv, can you please specify more details - does this corruption is consistent or happens rarely? Do you create/manage snapshots while the image is up? If no special snapshot action taken, what's the guest do between the boot and the shutdown? (Just to make sure, you do not run multiple guests with the same image right?) ---------------------------------------------------------------------- Comment By: Daniel van Vugt (danv) Date: 2009-01-13 16:48 Message: Confirmed on kvm-82. I am getting reproducible qcow2 corruption on my Windows images. Host: Ubuntu 8.04.1 amd64 (Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz) Guest: Multiple (see below) Summary is: 1. Boot working Windows image (qcow2) 2. Use Windows and then shut down the VM cleanly. 3. Image file is now corrupt and unusable. Won't boot again and qemu-img reports invalid information. Confirmed with multiple Windows Server 2003 guests and now Windows 7 beta too: $ qemu-img info windows7beta.qcow2 image: windows7beta.qcow2 file format: qcow2 virtual size: 20G (21474836480 bytes) disk size: 5.0G cluster_size: 4096 Snapshot list: ID TAG VM SIZE DATE VM CLOCK 1 Fresh_install 1.3M 2009-01-09 15:34:31 00:00:00.000 2 Activated_kvm-82 1.3M 2009-01-09 15:43:27 00:00:00.000 $ qemu -m 512 -usbdevice tablet -redir tcp:3389::3389 windows7beta.qcow2 & (use and then shut down windows) $ qemu-img info windows7beta.qcow2 image: windows7beta.qcow2 file format: raw <---------------------------- INVALID virtual size: 5.0G (5353566208 bytes) <--------- INVALID disk size: 5.0G $ qemu -m 512 -usbdevice tablet -redir tcp:3389::3389 windows7beta.qcow2 -S & (qemu) info snapshots Snapshot devices: ide0-hd0 bdrv_snapshot_list: error -95 ---------------------------------------------------------------------- Comment By: roy anonymous (roy-anonymous) Date: 2009-01-08 02:14 Message: I am not quite sure it's true or not, for my case, I get corruption if I have a new FC9 Guest installation with qcow2 with virtio_blk. But it won't have any problem if I install with a FC8 qcow2 installation, then upgrade to FC9 with virtio_blk ---------------------------------------------------------------------- Comment By: Laszlo Dvornik (ldvornik) Date: 2009-01-07 16:42 Message: Same problem here. With Lenny and vanilla 2.6.28 kernel, with KVM 79, and with KVM 82 user tools. Tried with KVM 82 module compile for 2.6.28 and with 2.6.28 builtin KVM sources. 32-bit userspace and kernel, Intel C2D T7100. Another effect: With empty qcow2, vmdk disk image formats, when I try to create a partition and save the new partition table, they can't save it until reboot. With raw image format there is no such problem. I liked to try with qcow, but: qemu: could not open disk image teszt.qcow I switched all of my disk images to raw, until the problem fixed. PS: The host filesystem is ext4, but I tested under ext3 filesystem too and the problem wasn't disappeared. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=893831&aid=2490866&group_id=180599 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
