On Tue, Mar 12, 2013 at 5:06 PM, Josh Durgin <[email protected]>wrote:
> On 03/12/2013 01:48 PM, Travis Rhoden wrote: > >> Hi Josh, >> >> Thanks for the info. So if I want to do live migration with VMs that were >> launched with boot-from-volume, I'll need to use virsh to do the >> migration, >> rather than Nova. Okay, that should be doable. As an aside, I will >> probably want to look at the OpenStack DB and figure out how to tell it >> that the VM has moved to a different host. I'd rather there not be a >> disconnect between Nova and libvirt about where the VM lives. =) >> > > It's probably not too hard to edit nova to skip the checks when the > instance is volume-backed, but if you don't want to do that, libvirt > should be fine, and a bit more flexible. > After messing with it for a few hours, I'm thinking about doing just that. The nova edits should be easy. Looks like it tests for shared storage by writing a file on the migration destination, and trying to read it at the source. I should be able to just comment out the check entirely, or make the check always pass. The virsh migrate strategy has been surprisingly difficult. Since I'm migrating a Nova VM, I had to the following pre-requisites (so far). Define the /var/lib/nova/instance/<domain> dir on the destination Define/migrate the nova libvirt-nwfilter for the specific VM Then, when I try to do the actual migration, I always get (at the source): error: internal error Process exited while reading console log output: chardev: opening backend "file" failed: Permission denied So QEMU is bailing, saying it can't read the console.log file. When I go look at that file, it is created, but with owner root:root and perms 0600. However, libvirtd makes it libvirt-qemu:kvm, 0600 before KVM tries to actually start the VM. I've always found this dynamic file ownership bit in KVM/libvirt/qemu very confusing. Anyways, I tried a few different things, debug logging, etc. Even tried disabling apparmor. Still get permission denied each time. The commands I"m running manually should be identical to what OpenStack is doing, so I can't figure out why their migrate is working and mine wouldn't. Oh well, will edit Nova and give that shot. - Travis
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