yahoo-eng-team team mailing list archive

[Balazs Gibizer <1932213@xxxxxxxxxxxxxxxxxx>]

This is intentional. As described in the code comment above the code you
linked. When the migration is forced Nova does not use the scheduler /
placement and therefore does not have knowledge what to do with
allocations that are not on the root provider. The allocation on the
root provider just blindly copied from src to dest.

Please note that providing a target host for live migration does not
mean such migration needs to be forced. See https://docs.openstack.org
/api-ref/compute/?expanded=live-migrate-server-os-migratelive-action-
detail :

host body string

The host to which to migrate the server. If this parameter is None, the scheduler chooses a host.
 
Warning

Prior to microversion 2.30, specifying a host will bypass validation by
the scheduler, which could result in failures to actually migrate the
instance to the specified host, or over-subscription of the host. It is
recommended to either not specify a host so that the scheduler will pick
one, or specify a host with microversion >= 2.30 and without force=True
set.

--

So when you specify a host with microversion >= 2.30 and without
force=True, then the scheduler and placement will be used so and you
will not hit the limitation of complex allocations. Still please note
that nova does not officially support sharing disk providers as we are
not test that. So other issues might pop up.


I'm closing this as Invalid as it is not a bug but an intentional behavior. If you disagree please set it back to New.

** Changed in: nova
       Status: New => Invalid

-- 
You received this bug notification because you are a member of Yahoo!
Engineering Team, which is subscribed to OpenStack Compute (nova).
https://bugs.launchpad.net/bugs/1932213

Title:
  live migration failed with: The instance has complex allocations on
  the source host so move cannot be forced

Status in OpenStack Compute (nova):
  Invalid

Bug description:
  we are having 2 compute nodes and we want to 
  those 2 compute nodes using nfs to share disk so there are 3 resource providers

  compute node1 for cpu/mem
  compute node2 for cpu/mem
  disk pool for shared storage

  now we want to live migrate the VM from compute 1 to compute 2

  
  it's facing this issue

  live migration error: No valid host was found. Unable to move instance
  a0b9c704-ad31-4be7-8f39-6ccf399807c4 to host kvm4ci10. The instance
  has complex allocations on the source host so move cannot be forced

  https://github.com/openstack/nova/blob/master/nova/scheduler/utils.py#L802

  seems this only happen when the live migration dest is specified (not
  given the dest is ok)

  
  but live migraiton to given host is a common use case as far as we can tell..

To manage notifications about this bug go to:
https://bugs.launchpad.net/nova/+bug/1932213/+subscriptions