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[Thierry Carrez <thierry.carrez+lp@xxxxxxxxx>]

** Changed in: nova
       Status: Fix Committed => Fix Released

** Changed in: nova
    Milestone: None => kilo-3

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https://bugs.launchpad.net/bugs/1406167

Title:
  Block migration fails because destination compute node refuses ssh
  connection

Status in OpenStack Compute (Nova):
  Fix Released

Bug description:
  Summary:
  When block-migrating a vm between two compute nodes, if the destination node lacks ssh daemon or refuses ssh connection, the block-migration would fail and cause damage to the vm, vm will be in error state for a certain time.

  Scenario:
  Block-migrating a vm between two compute nodes

  Example:
  Compute Node 1: ly-compute1 (10.0.0.31)
  Compute Node 2: ly-compute2 (10.0.0.32) with VM: test11

  The below tutorial is what I followed for openstack installation, it doesn't say about installing ssh support on compute nodes, so I didn't install ssh on both compute nodes.
  OpenStack Installation Guide for Ubuntu 12.04/14.04 (LTS)
  http://docs.openstack.org/icehouse/install-guide/install/apt/content/

  Error occurs when I use the command "nova migrate --poll test11" trying to migrate vm "test11" from ly-compute2 to ly-compute1.
  both error message and log said that ssh connecting to 10.0.0.31 failed (because ssh daemon is NOT even installed.) And the vm "test11" will enter a vm_state error state.
  *********************************************************************
  Tring to migrate:
  C:\Windows\system32>nova migrate --poll test11

  Server migrating... 0% complete
  Error migrating server
  ERROR (InstanceInErrorState): Unexpected error while running command.
  Command: ssh 10.0.0.31 mkdir -p /var/lib/nova/instances/30c4dac1-f3bc-4e6a-8a38-ee49671eee6a
  Exit code: 255
  Stdout: u''
  Stderr: u'ssh: connect to host 10.0.0.31 port 22: Connection refused\r\n'
  *********************************************************************
  dashboard log message:
  Unexpected error while running command. Command: ssh 10.0.0.31 mkdir -p /var/lib/nova/instances/30c4dac1-f3bc-4e6a-8a38-ee49671eee6a Exit code: 255 Stdout: u'' Stderr: u'ssh: connect to host 10.0.0.31 port 22: Connection refused\r\n'
  Code
  500
  Details
  File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 290, in decorated_function return function(self, context, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 3472, in resize_instance block_device_info)
  File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 4954, in migrate_disk_and_power_off utils.execute('ssh', dest, 'mkdir', '-p', inst_base)
  File "/usr/lib/python2.7/dist-packages/nova/utils.py", line 165, in execute return processutils.execute(*cmd, **kwargs)
  File "/usr/lib/python2.7/dist-packages/nova/openstack/common/processutils.py", line 195, in execute cmd=sanitized_cmd)
  *********************************************************************
  Second time tring to migrate:
  C:\Windows\system32>nova migrate --poll test11

  ERROR (Conflict): Cannot 'migrate' while instance is in vm_state error (HTTP 409) (Request-ID: req-ba3ca8e1-0753-40ac-9e2e-2f7c319ec691)
  *********************************************************************

  Request:
  This fault can be dangerous, because it will cause damage to the vm of a user. The migrate_disk_and_power_off function from nova/virt/libvirt/driver.py should pre-check if ssh daemon is running on dest node, before the actual block-migration process.

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