os-brick/os_brick/initiator/initiator_connector.py
Gorka Eguileor 400ca5d6db Refactor iSCSI disconnect
This patch refactors iSCSI disconnect code changing the approach to one
that just uses `iscsiadm -m session` and sysfs to get all the required
information: devices from the connection, multipath system device name,
multipath name, the WWN for the block devices...

By doing so, not only do we fix a good number of bugs, but we also
improve the reliability and speed of the mechanism.

A good example of improvements and benefits achieved by this patch are:

- Common code for multipath and single path disconnects.

- No more querying iSCSI devices for their WWN (page 0x83) removing
  delays and issue on flaky connections.

- All devices are properly cleaned even if they are not part of the
  multipath.

- We wait for device removal and do it in parallel if there are
  multiple.

- Removed usage of `multipath -l` to find devices which is really slow
  with flaky connections and didn't work when called with a device from
  a path that is down.

- Prevent losing data when detaching, currently if the multipath flush
  fails for any other reason than "in use" we silently continue with the
  removal.  That is the case when all paths are momentarily down.

- Adds a new mechanism for the caller of the disconnect to specify that
  it's acceptable to lose data and that it's more important to leave a
  clean system.  That is the case if we are creating a volume from an
  image, since the volume will just be set to error, but we don't want
  leftovers.  Optionally we can tell os-brick to ignore errors and don't
  raise an exception if the flush fails.

- Add a warning when we could be leaving leftovers behind due to
  disconnect issues.

- Action retries (like multipath flush) will now only log the final
  exception instead of logging all the exceptions.

- Flushes of individual paths now use exponential backoff retries
  instead of random retries between 0.2 and 2 seconds (from oslo
  library).

- We no longer use symlinks from `/dev/disk/by-path`, `/dev/disk/by-id`,
  or `/dev/mapper` to find devices or multipaths, as they could be
  leftovers from previous runs.

- With high failure rates (above 30%) some CLI calls will enter into a
  weird state where they wait forever, so we add a timeout mechanism in
  our `execute` method and add it to those specific calls.

Closes-Bug: #1502534
Change-Id: I058ff0a0e5ad517507dc3cda39087c913558561d
2017-05-31 15:31:20 +02:00

198 lines
7.0 KiB
Python

# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import abc
import six
from os_brick import exception
from os_brick import executor
from os_brick import initiator
@six.add_metaclass(abc.ABCMeta)
class InitiatorConnector(executor.Executor):
# This object can be used on any platform (x86, S390)
platform = initiator.PLATFORM_ALL
# This object can be used on any os type (linux, windows)
os_type = initiator.OS_TYPE_ALL
def __init__(self, root_helper, driver=None, execute=None,
device_scan_attempts=initiator.DEVICE_SCAN_ATTEMPTS_DEFAULT,
*args, **kwargs):
super(InitiatorConnector, self).__init__(root_helper, execute=execute,
*args, **kwargs)
self.device_scan_attempts = device_scan_attempts
def set_driver(self, driver):
"""The driver is used to find used LUNs."""
self.driver = driver
@abc.abstractmethod
def get_connector_properties(root_helper, *args, **kwargs):
"""The generic connector properties."""
pass
@abc.abstractmethod
def check_valid_device(self, path, run_as_root=True):
"""Test to see if the device path is a real device.
:param path: The file system path for the device.
:type path: str
:param run_as_root: run the tests as root user?
:type run_as_root: bool
:returns: bool
"""
pass
@abc.abstractmethod
def connect_volume(self, connection_properties):
"""Connect to a volume.
The connection_properties describes the information needed by
the specific protocol to use to make the connection.
The connection_properties is a dictionary that describes the target
volume. It varies slightly by protocol type (iscsi, fibre_channel),
but the structure is usually the same.
An example for iSCSI:
{'driver_volume_type': 'iscsi',
'data': {
'target_luns': [0, 2],
'target_iqns': ['iqn.2000-05.com.3pardata:20810002ac00383d',
'iqn.2000-05.com.3pardata:21810002ac00383d'],
'target_discovered': True,
'encrypted': False,
'qos_specs': None,
'target_portals': ['10.52.1.11:3260', '10.52.2.11:3260'],
'access_mode': 'rw',
}}
An example for fibre_channel:
{'driver_volume_type': 'fibre_channel',
'data': {
'initiator_target_map': {'100010604b010459': ['21230002AC00383D'],
'100010604b01045d': ['21230002AC00383D']
},
'target_discovered': True,
'encrypted': False,
'qos_specs': None,
'target_lun': 1,
'access_mode': 'rw',
'target_wwn': [
'20210002AC00383D',
'20220002AC00383D',
],
}}
:param connection_properties: The dictionary that describes all
of the target volume attributes.
:type connection_properties: dict
:returns: dict
"""
pass
@abc.abstractmethod
def disconnect_volume(self, connection_properties, device_info,
force=False, ignore_errors=False):
"""Disconnect a volume from the local host.
The connection_properties are the same as from connect_volume.
The device_info is returned from connect_volume.
:param connection_properties: The dictionary that describes all
of the target volume attributes.
:type connection_properties: dict
:param device_info: historical difference, but same as connection_props
:type device_info: dict
:param force: Whether to forcefully disconnect even if flush fails.
:type force: bool
:param ignore_errors: When force is True, this will decide whether to
ignore errors or raise an exception once finished
the operation. Default is False.
:type ignore_errors: bool
"""
pass
@abc.abstractmethod
def get_volume_paths(self, connection_properties):
"""Return the list of existing paths for a volume.
The job of this method is to find out what paths in
the system are associated with a volume as described
by the connection_properties.
:param connection_properties: The dictionary that describes all
of the target volume attributes.
:type connection_properties: dict
"""
pass
@abc.abstractmethod
def get_search_path(self):
"""Return the directory where a Connector looks for volumes.
Some Connectors need the information in the
connection_properties to determine the search path.
"""
pass
@abc.abstractmethod
def extend_volume(self, connection_properties):
"""Update the attached volume's size.
This method will attempt to update the local hosts's
volume after the volume has been extended on the remote
system. The new volume size in bytes will be returned.
If there is a failure to update, then None will be returned.
:param connection_properties: The volume connection properties.
:returns: new size of the volume.
"""
pass
@abc.abstractmethod
def get_all_available_volumes(self, connection_properties=None):
"""Return all volumes that exist in the search directory.
At connect_volume time, a Connector looks in a specific
directory to discover a volume's paths showing up.
This method's job is to return all paths in the directory
that connect_volume uses to find a volume.
This method is used in coordination with get_volume_paths()
to verify that volumes have gone away after disconnect_volume
has been called.
:param connection_properties: The dictionary that describes all
of the target volume attributes.
:type connection_properties: dict
"""
pass
def check_IO_handle_valid(self, handle, data_type, protocol):
"""Check IO handle has correct data type."""
if (handle and not isinstance(handle, data_type)):
raise exception.InvalidIOHandleObject(
protocol=protocol,
actual_type=type(handle))