path: root/results/scraper/launchpad/1894818

COLO's guest VNC client hang after failover

Hello,

After setting up COLO's primary and secondary VMs,
I installed the vncserver and xrdp (apt install tightvncserver xrdp) inside the VM.

I access the VM from another PC via VNC/RDP client, and everything is OK.
Then, kill the primary VM and issue the failover commands.

The expected result is that the VNC/RDP client can resume after failover.
But in my test, the VNC client's screen hangs and cannot be recovered no longer.

BTW, it works well after killing SVM.

Thanks.

Regards,
Derek

On Tue, 08 Sep 2020 10:25:52 -0000
Launchpad Bug Tracker <email address hidden> wrote:

> You have been subscribed to a public bug by Derek Su (dereksu):
> 
> Hello,
> 
> After setting up COLO's primary and secondary VMs,
> I installed the vncserver and xrdp (apt install tightvncserver xrdp) inside the VM.
> 
> I access the VM from another PC via VNC/RDP client, and everything is OK.
> Then, kill the primary VM and issue the failover commands.
> 
> The expected result is that the VNC/RDP client can reconnect and resume
> automatically after failover. (I've confirmed the VNC/RDP client can
> reconnect automatically.)
> 
> But in my test, the VNC client's screen hangs and cannot be recovered no
> longer. (I need to restart VNC client by myself.)
> 
> BTW, it works well after killing SVM.
> 
> Here is my QEMU networking device
> ```
> -device virtio-net-pci,id=e0,netdev=hn0 \
> -netdev tap,id=hn0,br=br0,vhost=off,helper=/usr/local/libexec/qemu-bridge-helper \
> ```
> 
> Thanks.
> 
> Regards,
> Derek
> 
> ** Affects: qemu
>      Importance: Undecided
>          Status: New
> 

Hello,
Can you show the full qemu command line?

Regards,
Lukas Straub


Hi, Lukas

It caused by the advanced watchdog (AWD) feature instead of COLO itself.
I will check it if my misuse or not, thanks.

Best regards,

Derek

Lukas Straub <email address hidden> 於 2020年9月8日 週二 下午8:30寫道：

> On Tue, 08 Sep 2020 10:25:52 -0000
> Launchpad Bug Tracker <email address hidden> wrote:
>
> > You have been subscribed to a public bug by Derek Su (dereksu):
> >
> > Hello,
> >
> > After setting up COLO's primary and secondary VMs,
> > I installed the vncserver and xrdp (apt install tightvncserver xrdp)
> inside the VM.
> >
> > I access the VM from another PC via VNC/RDP client, and everything is OK.
> > Then, kill the primary VM and issue the failover commands.
> >
> > The expected result is that the VNC/RDP client can reconnect and resume
> > automatically after failover. (I've confirmed the VNC/RDP client can
> > reconnect automatically.)
> >
> > But in my test, the VNC client's screen hangs and cannot be recovered no
> > longer. (I need to restart VNC client by myself.)
> >
> > BTW, it works well after killing SVM.
> >
> > Here is my QEMU networking device
> > ```
> > -device virtio-net-pci,id=e0,netdev=hn0 \
> > -netdev
> tap,id=hn0,br=br0,vhost=off,helper=/usr/local/libexec/qemu-bridge-helper \
> > ```
> >
> > Thanks.
> >
> > Regards,
> > Derek
> >
> > ** Affects: qemu
> >      Importance: Undecided
> >          Status: New
> >
>
> Hello,
> Can you show the full qemu command line?
>
> Regards,
> Lukas Straub
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1894818
>
> Title:
>   COLO's guest VNC client hang after failover
>
> Status in QEMU:
>   New
>
> Bug description:
>   Hello,
>
>   After setting up COLO's primary and secondary VMs,
>   I installed the vncserver and xrdp (apt install tightvncserver xrdp)
> inside the VM.
>
>   I access the VM from another PC via VNC/RDP client, and everything is OK.
>   Then, kill the primary VM and issue the failover commands.
>
>   The expected result is that the VNC/RDP client can reconnect and
>   resume automatically after failover. (I've confirmed the VNC/RDP
>   client can reconnect automatically.)
>
>   But in my test, the VNC client's screen hangs and cannot be recovered
>   no longer. I need to restart VNC client by myself.
>
>   BTW, it works well after killing SVM.
>
>   Here is my QEMU networking device
>   ```
>   -device virtio-net-pci,id=e0,netdev=hn0 \
>   -netdev
> tap,id=hn0,br=br0,vhost=off,helper=/usr/local/libexec/qemu-bridge-helper \
>   ```
>
>   Thanks.
>
>   Regards,
>   Derek
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/qemu/+bug/1894818/+subscriptions
>


Hi, Lukas

After fixing the misuse of AWD.
There is still a high probability of the VNC/RDP client hangs after PVM died and SVM takeover.

Here are the steps.

1. Start PVM script
```
imagefolder="/mnt/nfs2/vms"
  
 qemu-system-x86_64 -enable-kvm -cpu qemu64,+kvmclock -m 4096 -smp 2 -qmp stdio \                   
   -device piix3-usb-uhci -device usb-tablet -name primary \
   -device virtio-net-pci,id=e0,netdev=hn0 \
   -netdev tap,id=hn0,br=br0,vhost=off,helper=/usr/local/libexec/qemu-bridge-helper \
   -chardev socket,id=mirror0,host=0.0.0.0,port=9003,server,nowait \
   -chardev socket,id=compare1,host=0.0.0.0,port=9004,server,wait \
   -chardev socket,id=compare0,host=127.0.0.1,port=9001,server,nowait \
   -chardev socket,id=compare0-0,host=127.0.0.1,port=9001 \
   -chardev socket,id=compare_out,host=127.0.0.1,port=9005,server,nowait \
   -chardev socket,id=compare_out0,host=127.0.0.1,port=9005 \
   -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 \
   -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out \
   -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 \
   -object iothread,id=iothread1 \
   -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,\
outdev=compare_out0,iothread=iothread1 \
   -drive if=ide,id=colo-disk0,driver=quorum,read-pattern=fifo,vote-threshold=1,\
children.0.file.filename=$imagefolder/primary.qcow2,children.0.driver=qcow2 -vnc :0 -S
```

2. Start SVM script
```
#!/bin/bash
  
imagefolder="/mnt/nfs2/vms"
primary_ip=127.0.0.1

qemu-img create -f qcow2 $imagefolder/secondary-active.qcow2 100G
qemu-img create -f qcow2 $imagefolder/secondary-hidden.qcow2 100G

qemu-system-x86_64 -enable-kvm -cpu qemu64,+kvmclock -m 4096 -smp 2 -qmp stdio \
-device piix3-usb-uhci -device usb-tablet -name secondary \
-device virtio-net-pci,id=e0,netdev=hn0 \                                                           
-netdev tap,id=hn0,br=br0,vhost=off,helper=/usr/local/libexec/qemu-bridge-helper \
-chardev socket,id=red0,host=$primary_ip,port=9003,reconnect=1 \
-chardev socket,id=red1,host=$primary_ip,port=9004,reconnect=1 \
-object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 \
-object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 \
-object filter-rewriter,id=rew0,netdev=hn0,queue=all \
-drive if=none,id=parent0,file.filename=$imagefolder/secondary.qcow2,driver=qcow2 \
-drive if=none,id=childs0,driver=replication,mode=secondary,file.driver=qcow2,\
top-id=colo-disk0,file.file.filename=$imagefolder/secondary-active.qcow2,\
file.backing.driver=qcow2,file.backing.file.filename=$imagefolder/secondary-hidden.qcow2,\
file.backing.backing=parent0 \
-drive if=ide,id=colo-disk0,driver=quorum,read-pattern=fifo,vote-threshold=1,children.0=childs0 \
-vnc :1 \
-incoming tcp:0.0.0.0:9998
```

3. On Secondary VM's QEMU monitor, issue command
{'execute':'qmp_capabilities'}
{'execute': 'nbd-server-start', 'arguments': {'addr': {'type': 'inet', 'data': {'host': '0.0.0.0', 'port': '9999'} } } }
{'execute': 'nbd-server-add', 'arguments': {'device': 'parent0', 'writable': true } }

4. On Primary VM's QEMU monitor, issue command:
{'execute':'qmp_capabilities'}
{'execute': 'human-monitor-command', 'arguments': {'command-line': 'drive_add -n buddy driver=replication,mode=primary,file.driver=nbd,file.host=127.0.0.2,file.port=9999,file.export=parent0,node-name=replication0'}}
{'execute': 'x-blockdev-change', 'arguments':{'parent': 'colo-disk0', 'node': 'replication0' } }
{'execute': 'migrate-set-capabilities', 'arguments': {'capabilities': [ {'capability': 'x-colo', 'state': true } ] } }
{'execute': 'migrate', 'arguments': {'uri': 'tcp:127.0.0.2:9998' } }

5. kill PVM

6. On SVM, issues
```
{'execute': 'nbd-server-stop'}
{'execute': 'x-colo-lost-heartbeat'}

{'execute': 'object-del', 'arguments':{ 'id': 'f2' } }
{'execute': 'object-del', 'arguments':{ 'id': 'f1' } }
{'execute': 'chardev-remove', 'arguments':{ 'id': 'red1' } }
{'execute': 'chardev-remove', 'arguments':{ 'id': 'red0' } }
```

I use "-device virtio-net-pci" here, but after replacing with "-device rtl8139",
the behavior seems normal.
Is "-device virtio-net-pci" available in COLO?

Thanks.

Regards,
Derek


Hi,

I also tested some emulated nic devices and virtio network devices (in the attachment).

The VNC client's screen cannot be recovered while using all virtio network devices and the emulated e1000e nic.

Thanks.

Regards,
Derek



The QEMU project is currently moving 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 the bug state to "Incomplete" now.

If the bug has already been fixed in the latest upstream version of QEMU,
then please close this ticket as "Fix released".

If it is not fixed yet and you think that this bug report here is still
valid, then you have two options:

1) If you already have an account on gitlab.com, please open a new ticket
for this problem in our new tracker here:

    https://gitlab.com/qemu-project/qemu/-/issues

and then close this ticket here on Launchpad (or let it expire auto-
matically after 60 days). Please mention the URL of this bug ticket on
Launchpad in the new ticket on GitLab.

2) If you don't have an account on gitlab.com and don't intend to get
one, but still would like to keep this ticket opened, then please switch
the state back to "New" or "Confirmed" within the next 60 days (other-
wise it will get closed as "Expired"). We will then eventually migrate
the ticket automatically to the new system (but you won't be the reporter
of the bug in the new system and thus you won't get notified on changes
anymore).

Thank you and sorry for the inconvenience.


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