Re: [libvirt] [PATCH] qemu: fix migration with local and VIR_STORAGE_TYPE_NETWORK disks
On 02/07/2018 12:05 PM, Daniel P. Berrangé wrote:
On Wed, Feb 07, 2018 at 11:57:19AM -0600, Chris Friesen wrote:
> In the current implementation of qemuMigrateDisk() the value of the
> "nmigrate_disks" parameter wrongly impacts the decision whether or not
> to migrate a disk that is not a member of "migrate_disks":
>
> 1) If "nmigrate_disks" is zero, "disk" is migrated if it's
non-shared
> non-readonly with source.
>
> 2) If "nmigrate_disks" is non-zero and "disk" is not a member of
> "migrate_disks" then "disk" is not migrated. This should instead
proceed
> with checking conditions as per 1) and allow migration of non-shared
> non-readonly disks with source.
Huh, this doesn't make sense. If an app has passed a list of disks
in migrate_disks, we must *never* touch any disk that is not present
in this list. If the app wanted the other disk(s) migrated, it would
have included it in the list of disks it passed in.
Okay, that makes sense. I can restore the "return false" here.
Are you okay with the other change?
Our original problem scenario was where the root disk is rbd and there is a
read-only ISO config-drive, and "nmigrate_disks" is zero. What we see in this
case is that qemuMigrateDisk() returns "true" for the rbd disk, which then
causes qemuMigrationPrecreateStorage() to fail with "pre-creation of storage
targets for incremental storage migration is not supported".
Chris