[Qemu-discuss] Antw: Re: Antw: raw block -> RBD live migration

[Steffen Weißgerber]

Hi Nikola,

are the virtualisation hosts based on equal hardware (especially cpu)?

What are the qemu parameters for the disks? Do you use virtio drivers
and caching options?

My default is 

-drive 
format=rbd,file=rbd:kvm/awv66_c:id=kvm,media=disk,if=virtio,discard=on,cache=writethrough

where kvm is the storage pool awv66_c the virtual disk.

And when you convert die virtual disc with qemu-convert offline all is fine?

Regards

Steffen

>>> Nikola Ciprich <address@hidden> schrieb am Dienstag, 19. Januar
2016 um 07:58:
> So I've done another test and unfortunately I can confirm that
> this kind of migration leads to data corruption - I've run
> chkdisk prior to migration, everything went without errors,
> then tried it after migration and it reported corrupted filesystem
> indexes again - I needed to reboot the machine and have it fixed..
> (windows 2012 R2 again)
> 
> any ideas?
> 
> BR
> 
> nik
> 
> 
> On Wed, Jan 13, 2016 at 01:30:28PM +0100, Nikola Ciprich wrote:
>> Hello Steffen,
>> 
>> thanks for your reply..
>> 
>> > 1. Did you test a migration to non-rbd storage succesfully without this
>> > bad behavior after migration?
>> nope, I was onbly testing migration to RBD, but it seemed to be OK. I only
>> have this one windows VM which seemed to be damaged, but I'm not sure if
>> it was caused by migration or not.. but it seems to be strange coincidence,
>> so I'm rather paranoid here..
>> 
>> 
>> > 
>> > 2. Did you install and run another vm on your rbd storage? Does this vm 
> perform normally?
>> yes, there are other machines working on this storage without issues..
>> also I've migrated other vms using this procedure without issues
>> 
>> so I'm still uncertain now, whether it's safe or not..
>> 
>> BR
>> 
>> nik
>> 
>> 
>> 
>> 
>> 
>> > 
>> > Regards
>> > 
>> > Steffen
>> > 
>> > 
>> > >>> Nikola Ciprich <address@hidden> schrieb am Mittwoch, 13. Januar
>> > 2016 um 08:29:
>> > > Hello qemu users,
>> > > 
>> > > I'd like to ask about nonshared migration..
>> > > 
>> > > I have a server with virtual machines running on raw block devices..
>> > > I'd like to migrate those to ceph / RBD storage without downtime.
>> > > 
>> > > I've tested following procedure (I'm using qemu-kvm + libvirt based 
>> > > management)
>> > > 
>> > > 1) create RBD devices of the same size
>> > > 2) create new XML domain definition file with storage changed to new RBD 
>> > > devices (vm-new.xml)
>> > > 3) migrate vm using libvirt:
>> > > migrate --verbose --xml /tmp/vm-new.xml --copy-storage-all --live 
>> > > vmlbx50 
>> > > qemu+tcp://lbxphav1a/system
>> > > 
>> > > this seemed to do the trick, I've tested it for both linux and windows 
>> > > machines.
>> > > 
>> > > however, one windows 2k12 machine slowed down badly after migration, and 
>> > > after reboot,
>> > > chkdisk showed lots of corrupted filesystem indexes (i'm not windows 
>> > > guru, 
> 
>> > > so
>> > > hopefully I'm not confusing this much). After fixing those, everything 
>> > > started
>> > > working OK again, but I'm now concerned whether this procedure is really 
>> > > safe..
>> > > 
>> > > is there enybody who could confirm or comment on this?
>> > > I'm using qemu-2.2.1 and libvirt 1.2.6 on source machine,
>> > > qemu-2.3.0 and libvirt 1.2.15 on target box..
>> > > 
>> > > thanks a lot in advance!
>> > > 
>> > > BR
>> > > 
>> > > nik
>> > > 
>> > > -- 
>> > > -------------------------------------
>> > > Ing. Nikola CIPRICH
>> > > LinuxBox.cz, s.r.o.
>> > > 28.rijna 168, 709 00 Ostrava
>> > > 
>> > > tel.:   +420 591 166 214
>> > > fax:    +420 596 621 273
>> > > mobil:  +420 777 093 799
>> > > www.linuxbox.cz 
>> > > 
>> > > mobil servis: +420 737 238 656
>> > > email servis: address@hidden 
>> > > -------------------------------------
>> > 
>> > 
>> > -- 
>> > Klinik-Service Neubrandenburg GmbH
>> > Allendestr. 30, 17036 Neubrandenburg
>> > Amtsgericht Neubrandenburg, HRB 2457
>> > Geschaeftsfuehrerin: Gudrun Kappich
>> > 
>> > 
>> 
>> -- 
>> -------------------------------------
>> Ing. Nikola CIPRICH
>> LinuxBox.cz, s.r.o.
>> 28.rijna 168, 709 00 Ostrava
>> 
>> tel.:   +420 591 166 214
>> fax:    +420 596 621 273
>> mobil:  +420 777 093 799
>> www.linuxbox.cz 
>> 
>> mobil servis: +420 737 238 656
>> email servis: address@hidden 
>> -------------------------------------
> 
> 
> 
> -- 
> -------------------------------------
> Ing. Nikola CIPRICH
> LinuxBox.cz, s.r.o.
> 28.rijna 168, 709 00 Ostrava
> 
> tel.:   +420 591 166 214
> fax:    +420 596 621 273
> mobil:  +420 777 093 799
> www.linuxbox.cz 
> 
> mobil servis: +420 737 238 656
> email servis: address@hidden 
> -------------------------------------

--
Klinik-Service Neubrandenburg GmbH
Allendestr. 30, 17036 Neubrandenburg
Amtsgericht Neubrandenburg, HRB 2457
Geschaeftsfuehrerin: Gudrun Kappich