deb-manila/doc/source/devref/zfs_on_linux_driver.rst

ZFS (on Linux) Driver

Manila ZFSonLinux share driver uses ZFS filesystem for exporting NFS shares. Written and tested using Linux version of ZFS.

Requirements

• 'NFS' daemon that can be handled via "exportfs" app.
• 'ZFS' filesystem packages, either Kernel or FUSE versions.
• ZFS zpools that are going to be used by Manila should exist and be configured as desired. Manila will not change zpool configuration.
• For remote ZFS hosts according to manila-share service host SSH should be installed.

• For ZFS hosts that support replication:

  • SSH access for each other should be passwordless.
  • Service IP addresses should be available by ZFS hosts for each other.

Supported Operations

The following operations are supported:

• Create NFS Share
• Delete NFS Share
• Manage NFS Share
• Unmanage NFS Share

• Allow NFS Share access

  • Only IP access type is supported for NFS
  • Both access levels are supported - 'RW' and 'RO'

• Deny NFS Share access
• Create snapshot
• Delete snapshot
• Manage snapshot
• Unmanage snapshot
• Create share from snapshot
• Extend share
• Shrink share

• Replication (experimental):

  • Create/update/delete/promote replica operations are supported

• Share migration (experimental)

Possibilities

• Any amount of ZFS zpools can be used by share driver.
• Allowed to configure default options for ZFS datasets that are used for share creation.
• Any amount of nested datasets is allowed to be used.
• All share replicas are read-only, only active one is RW.
• All share replicas are synchronized periodically, not continuously. So, status 'in_sync' means latest sync was successful. Time range between syncs equals to value of config global opt 'replica_state_update_interval'.
• Driver is able to use qualified extra spec 'zfsonlinux:compression'. It can contain any value that is supported by used ZFS app. But if it is disabled via config option with value 'compression=off', then it will not be used.

Restrictions

The ZFSonLinux share driver has the following restrictions:

• Only IP access type is supported for NFS.
• Only FLAT network is supported.
• 'Promote share replica' operation will switch roles of current 'secondary' replica and 'active'. It does not make more than one active replica available.
• 'SaMBa' based sharing is not yet implemented.
• 'Thick provisioning' is not yet implemented.

Known problems

• 'Promote share replica' operation will make ZFS filesystem that became secondary as RO only on NFS level. On ZFS level system will stay mounted as was - RW.

Backend Configuration

The following parameters need to be configured in the manila configuration file for the ZFSonLinux driver:

• share_driver = manila.share.drivers.zfsonlinux.driver.ZFSonLinuxShareDriver
• driver_handles_share_servers = False

• replication_domain = custom_str_value_as_domain_name

  • if empty, then replication will be disabled
  • if set then will be able to be used as replication peer for other backend with same value.

• zfs_share_export_ip = <user_facing IP address of ZFS host>
• zfs_service_ip = <IP address of service network interface of ZFS host>

• zfs_zpool_list = zpoolname1,zpoolname2/nested_dataset_for_zpool2

  • can be one or more zpools
  • can contain nested datasets

• zfs_dataset_creation_options = <list of ZFS dataset options>

  • readonly,quota,sharenfs and sharesmb options will be ignored

• zfs_dataset_name_prefix = <prefix>

  • Prefix to be used in each dataset name.

• zfs_dataset_snapshot_name_prefix = <prefix>

  • Prefix to be used in each dataset snapshot name.

• zfs_use_ssh = <boolean_value>

  • set 'False' if ZFS located on the same host as 'manila-share' service
  • set 'True' if 'manila-share' service should use SSH for ZFS configuration

• zfs_ssh_username = <ssh_username>

  • required for replication operations
  • required for SSH'ing to ZFS host if 'zfs_use_ssh' is set to 'True'

• zfs_ssh_user_password = <ssh_user_password>

  • password for 'zfs_ssh_username' of ZFS host.
  • used only if 'zfs_use_ssh' is set to 'True'

• zfs_ssh_private_key_path = <path_to_private_ssh_key>

  • used only if 'zfs_use_ssh' is set to 'True'

• zfs_share_helpers = NFS=manila.share.drivers.zfsonlinux.utils.NFSviaZFSHelper

  • Approach for setting up helpers is similar to various other share driver
  • At least one helper should be used.

• zfs_replica_snapshot_prefix = <prefix>

  • Prefix to be used in dataset snapshot names that are created by 'update replica' operation.

• zfs_migration_snapshot_prefix = <prefix>

  • Prefix to be used in dataset snapshot names that are created for 'migration' operation.

Restart of manila-share service is needed for the configuration changes to take effect.

The manila.share.drivers.zfsonlinux.driver Module

manila.share.drivers.zfsonlinux.driver

The manila.share.drivers.zfsonlinux.utils Module

manila.share.drivers.zfsonlinux.utils