COLO unable to failover to secondary VM

[PJ Tsao]

I test COLO feature on my host following docs/COLO-FT.txt in qemu folder, but fail to failover to secondary VM.
Is there any mistake in my execution steps?

Execution environment:
QEMU v2.12.0-rc4
OS: Ubuntu 16.04.3 LTS
Kernel: Linux 4.4.35
Secondary VM IP: noted as "a.b.c.d"

Execution steps:
# Primary
${COLO_PATH}/x86_64-softmmu/qemu-system-x86_64 \
    -enable-kvm \
    -m 512M \
    -smp 2 \
    -qmp stdio \
    -vnc :7 \
    -name primary \
    -device piix3-usb-uhci \
    -device usb-tablet \
    -netdev tap,id=tap0,vhost=off \
    -device virtio-net-pci,id=net-pci0,netdev=tap0 \
    -drive if=virtio,id=primary-disk0,driver=quorum,read-pattern=fifo,vote-threshold=1,\
        children.0.file.filename=${IMG_PATH},\
        children.0.driver=raw -S

# Secondary
${COLO_PATH}/x86_64-softmmu/qemu-system-x86_64 \
    -enable-kvm \
    -m 512M \
    -smp 2 \
    -qmp stdio \
    -vnc :8 \
    -name secondary \
    -device piix3-usb-uhci \
    -device usb-tablet \
    -netdev tap,id=tap1,vhost=off \
    -device virtio-net-pci,id=net-pci0,netdev=tap1 \
    -drive if=none,id=secondary-disk0,file.filename=${IMG_PATH},driver=raw,node-name=node0 \
    -drive if=virtio,id=active-disk0,driver=replication,mode=secondary,\
        file.driver=qcow2,top-id=active-disk0,\
        file.file.filename=$ACTIVE_DISK,\
        file.backing.driver=qcow2,\
        file.backing.file.filename=$HIDDEN_DISK,\
        file.backing.backing=secondary-disk0 \
    -incoming tcp:0:8888

# Enter into Secondary:
{'execute':'qmp_capabilities'}
{ 'execute': 'nbd-server-start',
    'arguments': {'addr': {'type': 'inet', 'data': {'host': 'a.b.c.d', 'port': '8889'} } }
}
{'execute': 'nbd-server-add', 'arguments': {'device': 'secondary-disk0', 'writable': true } }

# Enter into Primary:
{'execute':'qmp_capabilities'}
{'execute': 'human-monitor-command',
    'arguments': {
        'command-line': 'drive_add -n buddy driver=replication,mode=primary,file.driver=nbd,file.host=a.b.c.d,file.port=8889,file.export=secondary-disk0,node-name=nbd_client0'
    }
}
{ 'execute':'x-blockdev-change', 'arguments':{'parent': 'primary-disk0', 'node': 'nbd_client0' } }
{ 'execute': 'migrate-set-capabilities',
    'arguments': {'capabilities': [ {'capability': 'x-colo', 'state': true } ] } }
{ 'execute': 'migrate', 'arguments': {'uri': 'tcp:a.b.c.d:8888' } }

# To test failover
Primary
{ 'execute': 'x-blockdev-change', 'arguments': {'parent': 'primary-disk0', 'child': 'children.1'}}
{ 'execute': 'human-monitor-command','arguments': {'command-line': 'drive_del nbd_client0'}}

Secondary
{ 'execute': 'nbd-server-stop' }

Stop Primary
Send ^C signal to terminate PVM.

Secondary
{ "execute": "x-colo-lost-heartbeat" }

# Result:
Primary (Use ^C to terminate)
qemu-system-x86_64: Can't receive COLO message: Input/output error
qemu-system-x86_64: terminating on signal 2
{"timestamp": {"seconds": 1531815575, "microseconds": 997696}, "event": "SHUTDOWN", "data": {"guest":false}}

Secondary
{ 'execute': 'nbd-server-stop' }
{"return": {}}
{ "execute": "x-colo-lost-heartbeat" }
{"return": {}}
qemu-system-x86_64: Can't receive COLO message: Input/output error
Segmentation fault

[YanFu Cho (danielafu)]

I also meet the same problem.
Does anybody have solutions for this problem?

[Thomas Huth (th-huth)]

The QEMU project is currently considering to move its bug tracking to another system. For this we need to know which bugs are still valid and which could be closed already. Thus we are setting older bugs to "Incomplete" now.
If you still think this bug report here is valid, then please switch the state back to "New" within the next 60 days, otherwise this report will be marked as "Expired". Or mark it as "Fix Released" if the problem has been solved with a newer version of QEMU already. Thank you and sorry for the inconvenience.

[Launchpad Janitor (janitor)]

[Expired for QEMU because there has been no activity for 60 days.]