Re: [Qemu-discuss] Source of QCOW Image Corruption

[Andrew Martin]

Some additional information: 

Cloning the VM disk image with qemu-img convert results in an image that 
appears to be error free and can be mounted successfully: 
# qemu-img convert myvm.qcow2 -O qcow2 test.qcow2 
# qemu-img check test.qcow2 
No errors were found on the image. 


Also, the following error is logged in /var/log/libvirt/qemu/myvm.log when 
attempting to start the VM: 
# tail /var/log/libvirt/qemu/myvm.log 
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/sbin:/sbin:/bin 
QEMU_AUDIO_DRV=none /usr/bin/kvm -S -M pc-0.12 -enable-kvm -m 8192 -smp 6 -name 
myvm -uuid 14a9dd6b-7a80-b286-8558-8c0c1f0324dc -chardev 
socket,id=monitor,path=/var/lib/libvirt/qemu/myvm.monitor,server,nowait 
-monitor chardev:monitor -boot c -drive 
file=/mnt/storage/vmstore/disks/myvm.qcow2,if=virtio,index=0,boot=on,format=qcow2,cache=none
 -drive file=/dev/drbd1,if=virtio,index=1,format=raw -drive 
file=/dev/drbd2,if=virtio,index=2,format=raw -net 
nic,macaddr=00:16:3e:32:35:82,vlan=0,model=virtio,name=virtio.0 -net 
tap,fd=55,vlan=0,name=tap.0 -chardev pty,id=serial0 -serial chardev:serial0 
-parallel none -usb -vnc 127.0.0.1:0 -vga cirrus 
char device redirected to /dev/pts/0 
pci_add_option_rom: failed to find romfile "pxe-virtio.bin" 
qcow2_free_clusters failed: Invalid argument 


These systems are running the stock Ubuntu 10.04 version of qemu-common, 
qemu-kvm, and kvm (0.12.3+noroms-0ubuntu9.19). 


Thanks, 


Andrew 
----- Original Message -----

From: "Andrew Martin" <address@hidden> 
To: address@hidden 
Sent: Tuesday, August 14, 2012 1:53:44 PM 
Subject: [Qemu-discuss] Source of QCOW Image Corruption 

Hello, 

I have two KVM virtual machine nodes in a high-availability cluster using 
Pacemaker + Heartbeat on Ubuntu 10.04 Server amd64. This cluster hosts a single 
Ubuntu 10.04 VM which uses a qcow2 image file, myvm.qcow2, with a backing file, 
backingfile.qcow2. This morning, the VM suddenly powered off. I attempted to 
start it again with virsh start domain, but it would only start briefly and 
then power off again. I checked the qcow2 disk image and found countless 
corruption errors: 

address@hidden:/mnt/storage/vmstore/disks# qemu-img info myvm.qcow2 
image: myvm.qcow2 
file format: qcow2 
virtual size: 9.8G (10485760000 bytes) 
disk size: 13G 
cluster_size: 65536 
backing file: backingfile.qcow2 (actual path: backingfile.qcow2) 
Snapshot list: 
ID TAG VM SIZE DATE VM CLOCK 
1.5G 2056-05-05 21:01:212795663:45:42.642 
/archive/1006/20100627000/2il_root/save/archive/1002/20100204005/1 743M 
1995-08-16 12:47:352289751:06:20.183 
address@hidden:/mnt/storage/vmstore/disks# qemu-img check myvm.qcow2 2>&1 | 
head 
ERROR OFLAG_COPIED: offset=80000002047d0000 refcount=0 
ERROR OFLAG_COPIED: offset=8000000212e50000 refcount=0 
ERROR OFLAG_COPIED: offset=80000001ffde0000 refcount=0 
ERROR OFLAG_COPIED: offset=80000001ff710000 refcount=0 
ERROR OFLAG_COPIED: offset=8000000216ec0000 refcount=0 
ERROR OFLAG_COPIED: offset=8000000206db0000 refcount=0 
ERROR OFLAG_COPIED: offset=80000001ff720000 refcount=0 
ERROR OFLAG_COPIED: offset=80000001ffdf0000 refcount=0 
ERROR OFLAG_COPIED: offset=8000000212e60000 refcount=0 
ERROR OFLAG_COPIED: offset=8000000212e70000 refcount=0 
address@hidden:/mnt/storage/vmstore/disks# qemu-img info backingfile.qcow2 
image: backingfile.qcow2 
file format: qcow2 
virtual size: 9.8G (10485760000 bytes) 
disk size: 4.8G 
cluster_size: 65536 
address@hidden:/mnt/storage/vmstore/disks# qemu-img check backingfile.qcow2 
No errors were found on the image. 


I had this happen a month ago on the same machine but a different physical 
drive, so I do not believe it to be a physical disk failure. I can find nothing 
in /var/log that gives any more information related to this corruption. What 
other debug information can I provide to diagnose why these images are getting 
corrupted and taking these running VMs offline? 


Thanks, 


Andrew Martin