Storage Volumes, Disks

Todo

rework after iSCSI merge (see ‘Old Docs’) (todd or vish)

The cinder.volume.manager Module

Volume manager manages creating, attaching, detaching, and persistent storage.

Persistent storage volumes keep their state independent of instances. You can attach to an instance, terminate the instance, spawn a new instance (even one from a different image) and re-attach the volume with the same data intact.

Related Flags

volume_topic:What rpc topic to listen to (default: cinder-volume).
volume_manager:The module name of a class derived from manager.Manager (default: cinder.volume.manager.Manager).
volume_driver:Used by Manager. Defaults to cinder.volume.drivers.lvm.LVMISCSIDriver.
volume_group:Name of the group that will contain exported volumes (default: cinder-volumes)
num_shell_tries:
 Number of times to attempt to run commands (default: 3)
class VolumeManager(volume_driver=None, service_name=None, *args, **kwargs)

Bases: cinder.manager.SchedulerDependentManager

Manages attachable block storage devices.

VolumeManager.RPC_API_VERSION = '1.11'
VolumeManager.accept_transfer(*args, **kwargs)
VolumeManager.attach_volume(*args, **kwargs)

Updates db to show volume is attached

VolumeManager.copy_volume_to_image(*args, **kwargs)

Uploads the specified volume to Glance.

image_meta is a dictionary containing the following keys: ‘id’, ‘container_format’, ‘disk_format’

VolumeManager.create_snapshot(*args, **kwargs)

Creates and exports the snapshot.

VolumeManager.create_volume(*args, **kwargs)

Creates and exports the volume.

VolumeManager.delete_snapshot(*args, **kwargs)

Deletes and unexports snapshot.

VolumeManager.delete_volume(*args, **kwargs)

Deletes and unexports volume.

VolumeManager.detach_volume(*args, **kwargs)

Updates db to show volume is detached

VolumeManager.extend_volume(*args, **kwargs)
VolumeManager.init_host()

Do any initialization that needs to be run if this is a standalone service.

VolumeManager.initialize_connection(*args, **kwargs)

Prepare volume for connection from host represented by connector.

This method calls the driver initialize_connection and returns it to the caller. The connector parameter is a dictionary with information about the host that will connect to the volume in the following format:

{
    'ip': ip,
    'initiator': initiator,
}

ip: the ip address of the connecting machine

initiator: the iscsi initiator name of the connecting machine. This can be None if the connecting machine does not support iscsi connections.

driver is responsible for doing any necessary security setup and returning a connection_info dictionary in the following format:

{
    'driver_volume_type': driver_volume_type,
    'data': data,
}
driver_volume_type: a string to identify the type of volume. This
can be used by the calling code to determine the strategy for connecting to the volume. This could be ‘iscsi’, ‘rbd’, ‘sheepdog’, etc.
data: this is the data that the calling code will use to connect
to the volume. Keep in mind that this will be serialized to json in various places, so it should not contain any non-json data types.
VolumeManager.migrate_volume(*args, **kwargs)

Migrate the volume to the specified host (called on source host).

VolumeManager.migrate_volume_completion(ctxt, volume_id, new_volume_id, error=False)
VolumeManager.notification(context, event)
VolumeManager.publish_service_capabilities(context)

Collect driver status and then publish.

VolumeManager.terminate_connection(*args, **kwargs)

Cleanup connection from host represented by connector.

The format of connector is the same as for initialize_connection.

The cinder.volume.driver Module

Drivers for volumes.

class FakeISCSIDriver(*args, **kwargs)

Bases: cinder.volume.driver.ISCSIDriver

Logs calls instead of executing.

FakeISCSIDriver.check_for_setup_error()

No setup necessary in fake mode.

FakeISCSIDriver.create_volume(volume)
static FakeISCSIDriver.fake_execute(cmd, *_args, **_kwargs)

Execute that simply logs the command.

FakeISCSIDriver.initialize_connection(volume, connector)
FakeISCSIDriver.terminate_connection(volume, connector, **kwargs)
class FakeISERDriver(*args, **kwargs)

Bases: cinder.volume.driver.FakeISCSIDriver

Logs calls instead of executing.

static FakeISERDriver.fake_execute(cmd, *_args, **_kwargs)

Execute that simply logs the command.

FakeISERDriver.initialize_connection(volume, connector)
class FibreChannelDriver(*args, **kwargs)

Bases: cinder.volume.driver.VolumeDriver

Executes commands relating to Fibre Channel volumes.

FibreChannelDriver.initialize_connection(volume, connector)

Initializes the connection and returns connection info.

The driver returns a driver_volume_type of ‘fibre_channel’. The target_wwn can be a single entry or a list of wwns that correspond to the list of remote wwn(s) that will export the volume. Example return values:

{

‘driver_volume_type’: ‘fibre_channel’ ‘data’: {

‘target_discovered’: True, ‘target_lun’: 1, ‘target_wwn’: ‘1234567890123’, ‘access_mode’: ‘rw’

}

}

or

{

‘driver_volume_type’: ‘fibre_channel’ ‘data’: {

‘target_discovered’: True, ‘target_lun’: 1, ‘target_wwn’: [‘1234567890123’, ‘0987654321321’], ‘access_mode’: ‘rw’

}

}

class ISCSIDriver(*args, **kwargs)

Bases: cinder.volume.driver.VolumeDriver

Executes commands relating to ISCSI volumes.

We make use of model provider properties as follows:

provider_location
if present, contains the iSCSI target information in the same format as an ietadm discovery i.e. ‘<ip>:<port>,<portal> <target IQN>’
provider_auth
if present, contains a space-separated triple: ‘<auth method> <auth username> <auth password>’. CHAP is the only auth_method in use at the moment.
ISCSIDriver.accept_transfer(context, volume, new_user, new_project)
ISCSIDriver.get_target_admin()
ISCSIDriver.get_volume_stats(refresh=False)

Get volume stats.

If ‘refresh’ is True, run update the stats first.

ISCSIDriver.initialize_connection(volume, connector)

Initializes the connection and returns connection info.

The iscsi driver returns a driver_volume_type of ‘iscsi’. The format of the driver data is defined in _get_iscsi_properties. Example return value:

{
    'driver_volume_type': 'iscsi'
    'data': {
        'target_discovered': True,
        'target_iqn': 'iqn.2010-10.org.openstack:volume-00000001',
        'target_portal': '127.0.0.0.1:3260',
        'volume_id': 1,
        'access_mode': 'rw'
    }
}
ISCSIDriver.terminate_connection(volume, connector, **kwargs)
ISCSIDriver.validate_connector(connector)
class ISERDriver(*args, **kwargs)

Bases: cinder.volume.driver.ISCSIDriver

Executes commands relating to ISER volumes.

We make use of model provider properties as follows:

provider_location
if present, contains the iSER target information in the same format as an ietadm discovery i.e. ‘<ip>:<port>,<portal> <target IQN>’
provider_auth
if present, contains a space-separated triple: ‘<auth method> <auth username> <auth password>’. CHAP is the only auth_method in use at the moment.
ISERDriver.get_target_admin()
ISERDriver.initialize_connection(volume, connector)

Initializes the connection and returns connection info.

The iser driver returns a driver_volume_type of ‘iser’. The format of the driver data is defined in _get_iser_properties. Example return value:

{
    'driver_volume_type': 'iser'
    'data': {
        'target_discovered': True,
        'target_iqn':
        'iqn.2010-10.org.iser.openstack:volume-00000001',
        'target_portal': '127.0.0.0.1:3260',
        'volume_id': 1,
    }
}
class VolumeDriver(execute=<function execute at 0x7f5a4c4b4b18>, *args, **kwargs)

Bases: object

Executes commands relating to Volumes.

VolumeDriver.VERSION = 'N/A'
VolumeDriver.attach_volume(context, volume, instance_uuid, host_name, mountpoint)

Callback for volume attached to instance or host.

VolumeDriver.backup_volume(context, backup, backup_service)

Create a new backup from an existing volume.

VolumeDriver.check_for_setup_error()
VolumeDriver.clear_download(context, volume)

Clean up after an interrupted image copy.

VolumeDriver.clone_image(volume, image_location, image_id)

Create a volume efficiently from an existing image.

image_location is a string whose format depends on the image service backend in use. The driver should use it to determine whether cloning is possible.

image_id is a string which represents id of the image. It can be used by the driver to introspect internal stores or registry to do an efficient image clone.

Returns a dict of volume properties eg. provider_location, boolean indicating whether cloning occurred

VolumeDriver.copy_image_to_volume(context, volume, image_service, image_id)

Fetch the image from image_service and write it to the volume.

VolumeDriver.copy_volume_data(context, src_vol, dest_vol, remote=None)

Copy data from src_vol to dest_vol.

VolumeDriver.copy_volume_to_image(context, volume, image_service, image_meta)

Copy the volume to the specified image.

VolumeDriver.create_cloned_volume(volume, src_vref)

Creates a clone of the specified volume.

VolumeDriver.create_export(context, volume)

Exports the volume. Can optionally return a Dictionary of changes to the volume object to be persisted.

VolumeDriver.create_snapshot(snapshot)

Creates a snapshot.

VolumeDriver.create_volume(volume)

Creates a volume. Can optionally return a Dictionary of changes to the volume object to be persisted.

VolumeDriver.create_volume_from_snapshot(volume, snapshot)

Creates a volume from a snapshot.

VolumeDriver.delete_snapshot(snapshot)

Deletes a snapshot.

VolumeDriver.delete_volume(volume)

Deletes a volume.

VolumeDriver.detach_volume(context, volume)

Callback for volume detached.

VolumeDriver.do_setup(context)

Any initialization the volume driver does while starting

VolumeDriver.ensure_export(context, volume)

Synchronously recreates an export for a volume.

VolumeDriver.extend_volume(volume, new_size)
VolumeDriver.get_version()

Get the current version of this driver.

VolumeDriver.get_volume_stats(refresh=False)

Return the current state of the volume service. If ‘refresh’ is True, run the update first.

VolumeDriver.initialize_connection(volume, connector)

Allow connection to connector and return connection info.

VolumeDriver.initialized
VolumeDriver.local_path(volume)
VolumeDriver.migrate_volume(context, volume, host)

Migrate the volume to the specified host.

Returns a boolean indicating whether the migration occurred, as well as model_update.

VolumeDriver.remove_export(context, volume)

Removes an export for a volume.

VolumeDriver.restore_backup(context, backup, volume, backup_service)

Restore an existing backup to a new or existing volume.

VolumeDriver.set_execute(execute)
VolumeDriver.set_initialized()
VolumeDriver.terminate_connection(volume, connector, **kwargs)

Disallow connection from connector

VolumeDriver.validate_connector(connector)

Fail if connector doesn’t contain all the data needed by driver

Tests

The volume_unittest Module

Old Docs

Cinder uses iSCSI to export storage volumes from multiple storage nodes. These iSCSI exports are attached (using libvirt) directly to running instances.

Cinder volumes are exported over the primary system VLAN (usually VLAN 1), and not over individual VLANs.

The underlying volumes by default are LVM logical volumes, created on demand within a single large volume group.

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