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

[Peter Lieven]

Am 07.04.2015 um 17:29 schrieb Dr. David Alan Gilbert:
> * Peter Lieven (address@hidden) wrote:
>> Hi David,
>>
>> Am 07.04.2015 um 10:43 schrieb Dr. David Alan Gilbert:
>>>>>> 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.
>>> How often does it fail - you say 'sometimes' - is it a 1/10 or a 1/1000 ?
>> Its more often than 1/10 I would say.
> OK, that's not too bad - it's the 1/1000 that are really nasty to find.
> In your setup, how easy would it be for you to try :
>     with either 2.1 or current head?
>     with a newer machine-type?
>     without the cdrom?

Its all possible. I can clone the system and try everything on my test systems. 
I hope
it reproduces there.

Has the cdrom the power of taking down the bus?

Peter