Re: [libvirt] QEMU migration with non-shared storage

2014-09-11 Thread Guido Günther
On Thu, Sep 11, 2014 at 02:45:41PM +1000, Blair Bethwaite wrote: Hi Michael! On 11 September 2014 14:13, Michael Chapman m...@very.puzzling.org wrote: Why is RBD is handled specially in this function? The current logic is that an RBD-backed disk is safe to be migrated even if it's got

Re: [libvirt] QEMU migration with non-shared storage

2014-09-11 Thread Michael Chapman
On Thu, 11 Sep 2014, Blair Bethwaite wrote: A related problem arises mixing RBD and local disks when drive-mirroring / block-migrating - the RBDs get migrated too, volume round trips out of ceph - into source hypervisor - into dest hypervisor - back into ceph. Not great! This patch fixes that

[libvirt] QEMU migration with non-shared storage

2014-09-10 Thread Michael Chapman
Hello, I am trying to understand libvirt's logic for checking whether migration of a VM is safe, and how it determines which disks should be mirrored by QEMU. My particular use case involves VMs that may have disks backed onto LVM or onto Ceph RBD, or both. As far as I can tell, the

Re: [libvirt] QEMU migration with non-shared storage

2014-09-10 Thread Blair Bethwaite
Hi Michael! On 11 September 2014 14:13, Michael Chapman m...@very.puzzling.org wrote: Why is RBD is handled specially in this function? The current logic is that an RBD-backed disk is safe to be migrated even if it's got caching enabled, but I'm not sure how RBD is different from other