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

[Peter Lieven]

Am 09.04.2015 um 14:49 schrieb Peter Lieven:
> Am 07.04.2015 um 21:01 schrieb Dr. David Alan Gilbert:
> > * Peter Lieven (address@hidden) wrote:
> > > 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.
> > Great.  I think the order I would go would be:
> >      Try head - if it works we know we've already got the fix somewhere
> >      Try 2.1  - if it works we know it's something we introduced between
> >                 2.1 and 2.2.1
> >      Try a newer machine type - because pc-1.2 probably isn't tested much
> >      CDROM at the end.
>
> Update:
>  - head -> not working
>  - 2.1.3 -> not working
>  - without CROM -> not working
>  - with head and no machine type specified -> not working
>  - with -device isa-ide -> BIOS not booting harddisk
>
> Will now try 1.3.1 just to be sure.

1.3.1 => not working
kernel parameter ide=nodma (ide-core.nodma not supported by kernel) => not 
working.

I usually crash in my setup at around 50-80 migrations. In production it seems 
to happen more often.
Maybe it is load depending.

Peter