On 09/11/2012 08:35 AM, Daniel P. Berrange wrote:
Do we really need a new user-visible flag, or can we make this work automatically without having to involve the user? On the other hand, what happens if we do keep this as a user-visible flag? Should 'virsh migrate --offline' silently ignore the flag if the guest is online, or should it error out stating that the guest is running and not offline?
Also, I think we NEED to error out if the guest is offline but the --persistent flag is not set; that is, an offline migration only makes sense if the persistent flag has been requested, but I think that 'virsh migrate --persistent' should automatically be smart enough to do an offline migration.
No we must not do that. If a guest has shutoff we cannot assume that the user / app wants to copy it across to the other host. eg consider this scenario
admin a: check if guestfoo is running admin b: check if guestfoo is running admin a: migrate guestfoo barhost admin b: migrate guestfoo wizzhost
IMHO step 4 should fail unless the admin explicitly requested that they want to copy across the offline config
Good point - the new flag is necessary, and must be user-visible. At which point, do we argue that use of the MIGRATE_OFFLINE flag automatically implies MIGRATE_PERSISTENT, or should it be an error unless the user explicitly requests both flags? -- Eric Blake eblake@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org