openstack
/
nova
Code Issues Proposed changes

live-mig: keep disk device address same 

During live migration disk devices are updated with the latest
block device mapping information for volumes.  Previously this
relied on libvirt to assign addresses in order after the already
assigned devices like the root disk had been accounted for.  In
the latest libvirt the unassigned devices are allocated first which
makes the root disk address double allocated causing the migration to
fail.  A running instance should never have the hardware addresses
of its disks changed mid flight.  While disk address changes during
live migration produce fatal errors for the operator it would likely
cause errors inside the instance and unexpected behavior if the device
addresses change during cold migrationt review.  With this disk addresses are no
longer updated with block device mapping information while every
other element of the disk definition for a volume is updated.

Closes-Bug: 1715569

Change-Id: I17af9848f4c0edcbcb101b30e45ca4afa93dcdbb
(cherry picked from commit b196857f04)
This commit is contained in:
Mike Lowe 2017-11-06 11:06:46 -05:00 committed by sahid
parent 839f07fbbb
commit d91e881890
2 changed files with 77 additions and 5 deletions
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67
nova/tests/unit/virt/libvirt/test_migration.py
View File

@ -243,6 +243,73 @@ class UtilityMigrationTestCase(test.NoDBTestCase):
'ip-1.2.3.4:3260-iqn.cde.67890.opst-lun-Z')
self.assertThat(res, matchers.XMLMatches(new_xml))
def test_update_volume_xml_keeps_address(self):
# Now test to make sure address isn't altered for virtio-scsi and rbd
connection_info = {
'driver_volume_type': 'rbd',
'serial': 'd299a078-f0db-4993-bf03-f10fe44fd192',
'data': {
'access_mode': 'rw',
'secret_type': 'ceph',
'name': 'cinder-volumes/volume-d299a078',
'encrypted': False,
'discard': True,
'cluster_name': 'ceph',
'secret_uuid': '1a790a26-dd49-4825-8d16-3dd627cf05a9',
'qos_specs': None,
'auth_enabled': True,
'volume_id': 'd299a078-f0db-4993-bf03-f10fe44fd192',
'hosts': ['172.16.128.101', '172.16.128.121'],
'auth_username': 'cinder',
'ports': ['6789', '6789', '6789']}}
bdm = objects.LibvirtLiveMigrateBDMInfo(
serial='d299a078-f0db-4993-bf03-f10fe44fd192',
bus='scsi', type='disk', dev='sdc',
connection_info=connection_info)
data = objects.LibvirtLiveMigrateData(
target_connect_addr=None,
bdms=[bdm],
block_migration=False)
xml = """<domain>
<devices>
<disk type='network' device='disk'>
<driver name='qemu' type='raw' cache='writeback' discard='unmap'/>
<auth username='cinder'>
<secret type='ceph' uuid='1a790a26-dd49-4825-8d16-3dd627cf05a9'/>
</auth>
<source protocol='rbd' name='cinder-volumes/volume-d299a078'>
<host name='172.16.128.101' port='6789'/>
<host name='172.16.128.121' port='6789'/>
</source>
<backingStore/>
<target dev='sdb' bus='scsi'/>
<serial>d299a078-f0db-4993-bf03-f10fe44fd192</serial>
<alias name='scsi0-0-0-1'/>
<address type='drive' controller='0' bus='0' target='0' unit='1'/>
</disk>
</devices>
</domain>"""
conf = vconfig.LibvirtConfigGuestDisk()
conf.source_device = bdm.type
conf.driver_name = "qemu"
conf.driver_format = "raw"
conf.driver_cache = "writeback"
conf.target_dev = bdm.dev
conf.target_bus = bdm.bus
conf.serial = bdm.connection_info.get('serial')
conf.source_type = "network"
conf.driver_discard = 'unmap'
conf.device_addr = vconfig.LibvirtConfigGuestDeviceAddressDrive()
conf.device_addr.controller = 0
get_volume_config = mock.MagicMock(return_value=conf)
doc = etree.fromstring(xml)
res = etree.tostring(migration._update_volume_xml(
doc, data, get_volume_config), encoding='unicode')
new_xml = xml.replace('sdb',
'sdc')
self.assertThat(res, matchers.XMLMatches(new_xml))
def test_update_perf_events_xml(self):
data = objects.LibvirtLiveMigrateData(
supported_perf_events=['cmt'])

15
nova/virt/libvirt/migration.py
View File

@ -161,15 +161,20 @@ def _update_volume_xml(xml_doc, migrate_data, get_volume_config):
# If source and destination have same item, update
# the item using destination value.
for item_dst in xml_doc2.findall(item_src.tag):
disk_dev.remove(item_src)
item_dst.tail = None
disk_dev.insert(cnt, item_dst)
if item_dst.tag != 'address':
# hw address presented to guest must never change,
# especially during live migration as it can be fatal
disk_dev.remove(item_src)
item_dst.tail = None
disk_dev.insert(cnt, item_dst)
# If destination has additional items, thses items should be
# added here.
for item_dst in list(xml_doc2):
item_dst.tail = None
disk_dev.insert(cnt, item_dst)
if item_dst.tag != 'address':
# again, hw address presented to guest must never change
item_dst.tail = None
disk_dev.insert(cnt, item_dst)
return xml_doc