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[Bug 1628449] Re: Exception when live block migration multiple ephemerals

 

** Changed in: nova
   Importance: Undecided => Medium

** Tags removed: newton-backport-potential
** Tags added: libvirt live-migration

** Changed in: nova
   Importance: Medium => High

** Also affects: nova/newton
   Importance: Undecided
       Status: New

** Changed in: nova/newton
     Assignee: (unassigned) => sahid (sahid-ferdjaoui)

** Changed in: nova/newton
       Status: New => In Progress

** Changed in: nova/newton
   Importance: Undecided => High

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https://bugs.launchpad.net/bugs/1628449

Title:
  Exception when live block migration multiple ephemerals

Status in OpenStack Compute (nova):
  Fix Released
Status in OpenStack Compute (nova) newton series:
  In Progress

Bug description:
  When block live migrate an instance with multiple ephemeral an
  exception FlavorDiskSmallerThanImage is raised.

  
  Steps to Reproduce:
  1) Created flavor with two ephemeral support.

  ~~~
  [root@allinone9 ~(keystone_admin)]# nova flavor-create 2ephemeral-disks 6 512 1 1 --ephemeral 2
  ~~~

  2) Spawned instance using created flavor.

  ~~~
  [root@allinone9 ~(keystone_admin)]# nova boot --flavor 2ephemeral-disks --image cirros --ephemeral size=1 --ephemeral size=1 internal1
  ~~~

  3) Instance spawned successfully.

  ~~~
  [root@allinone9 ~(keystone_admin)]# nova list --field name,status,host | grep -i internal1
  | 08619d2d-e3a2-4f67-a959-33cfbc08d153 | internal1 | ACTIVE | allinone9 |
  ~~~

  4) Verifying that two extra ephemeral disks are connected with
  instance.

  ~~~
  [root@allinone9 ~(keystone_admin)]# virsh domblklist 4
  Target     Source
  ------------------------------------------------
  vda        /var/lib/nova/instances/08619d2d-e3a2-4f67-a959-33cfbc08d153/disk
  vdb        /var/lib/nova/instances/08619d2d-e3a2-4f67-a959-33cfbc08d153/disk.eph0
  vdc        /var/lib/nova/instances/08619d2d-e3a2-4f67-a959-33cfbc08d153/disk.eph1
  ~~~

  5) Tried to perform the block migration but it end with same error
  which you have seen.

  [root@allinone9 ~(keystone_admin)]# nova live-migration 08619d2d-
  e3a2-4f67-a959-33cfbc08d153 compute1-9 --block-migrate

  ~~~
  From : /var/log/nova/nova-compute.log

  2016-09-26 08:53:12.033 3958 ERROR nova.compute.manager [req-
  f24d49f7-4d8e-4683-bcc0-952254764fca b09d7a1af46d42398c79a1dc0da02954
  ca23990ed6c846b0b8d588fb5e304aeb - - -] [instance: 08619d2d-
  e3a2-4f67-a959-33cfbc08d153] Pre live migration failed at compute1-9

  2016-09-26 08:53:12.033 3958 ERROR nova.compute.manager [instance: 08619d2d-e3a2-4f67-a959-33cfbc08d153] 
  2016-09-26 08:53:12.033 3958 ERROR nova.compute.manager [instance: 08619d2d-e3a2-4f67-a959-33cfbc08d153] FlavorDiskSmallerThanImage: Flavor's disk is too small for requested image. Flavor disk is 1073741824 bytes, image is 2147483648 bytes.
  ~~~

  That error is because two mistake:

  ... LINE ~ 6588 in libvirt.py (method
  libvirt._create_images_and_backing)

  		image = self.image_backend.image(instance,
  	                                         instance_disk,
  	                                         CONF.libvirt.images_type)
                  if cache_name.startswith('ephemeral'):
                      image.cache(fetch_func=self._create_ephemeral,
  				fs_label=cache_name,
  				os_type=instance.os_type,
  	                        filename=cache_name,
                                  size=info['virt_disk_size'],                  (a)
                                  ephemeral_size=instance.flavor.ephemeral_gb)  (b) 
  	        elif cache_name.startswith('swap'):
  	            inst_type = instance.get_flavor()
                      swap_mb = inst_type.swap

  ...

  
  (a) That argument 'size' does not exist in _create_ephemeral
  (b) We should report here the actual size of the ephemeral disk (which is what has been asked by user during boot insteado of the total size allowed by the flavor for ephemeral disks)

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References