Re: [Qemu-block] Migration sometimes fails with IDE and Qemu 2.2.1

[Peter Lieven]

Am 06.04.2015 um 21:02 schrieb Peter Lieven:
> Am 06.04.2015 um 20:50 schrieb John Snow:
>>
>> On 04/06/2015 02:47 PM, Peter Lieven wrote:
>>> Hi all,
>>>
>>> is there a known issue in Qemu 2.2.1 where IDE stalls sometimes after a 
>>> migration with Qemu 2.2.1?
>>> The migration succeeds, but it seems that the complete I/O is hanging. This 
>>> happens only sometimes
>>> and only with extreme old Linux Guests (SLES 10 with Kernel 2.6.16) thus 
>>> the IDE controller as
>>> storage controller for the system disk.
>>>
>>> Maybe this sounds familiar to someone.
>>>
>>> Thank you,
>>> Peter
>>>
>> It's news to me.
> Okay, I was hoping that I just missed a patch or someone forgot to CC 
> qemu-stable... :-)
>
>> Is this a regression?
> I can't say we see those vServers hang sometime after migration since we 
> changed the hypervisor from qemu-kvm-1.2.0 to qemu-2.2.0.
>
>
>> Any particular workload or reproducer?
> Workload is almost zero. I try to figure out if there is a way to trigger it.
>
> Maybe playing a role: Machine type is -M pc1.2 and we set -kvmclock as
> CPU flag since kvmclock seemed to be quite buggy in 2.6.16...
>
> Exact cmdline is:
> /usr/bin/qemu-2.2.1  -enable-kvm  -M pc-1.2  -nodefaults -netdev 
> type=tap,id=guest2,script=no,downscript=no,ifname=tap2  -device 
> e1000,netdev=guest2,mac=52:54:00:ff:00:65 -drive 
> format=raw,file=iscsi://172.21.200.53/iqn.2001-05.com.equallogic:4-52aed6-88a7e99a4-d9e00040fdc509a3-XXX-hd0/0,if=ide,cache=writeback,aio=native
>   -serial null  -parallel null  -m 1024 -smp 2,sockets=1,cores=2,threads=1  
> -monitor tcp:0:4003,server,nowait -vnc :3 -qmp tcp:0:3003,server,nowait -name 
> 'XXX' -boot order=c,once=dc,menu=off  -drive 
> index=2,media=cdrom,if=ide,cache=unsafe,aio=native,readonly=on  -k de  
> -incoming tcp:0:5003  -pidfile /var/run/qemu/vm-146.pid  -mem-path /hugepages 
>  -mem-prealloc  -rtc base=utc -usb -usbdevice tablet -no-hpet -vga cirrus  
> -cpu qemu64,-kvmclock
>
> Exact kernel is:
> 2.6.16.46-0.12-smp (i think this is SLES10 or sth.)
>
> The machine does not hang. It seems just I/O is hanging. So you can type at 
> the console or ping the system, but no longer login.
>
> Thank you,
> Peter

Interesting observation: Migrating the vServer again seems to fix to problem 
(at least in one case I could test just now).

2.6.8-24-smp is also affected.

Thanks,
Peter