openstack/manila
Code Issues Proposed changes
c1f575ec05
manila/doc/source/admin/zfs_on_linux_driver.rst
Tom Barron a149c283d7 doc: move stuff from contributor to admin 
As agreed in weekly manila community meetings and at the
Queens PTG, several documents currently presented to contributors
are really of general interest to cloud administrators and should
be presented accordingly.

Move the docs on manila back ends, the feature support mapping,
capabilities and extra specs, and export locations and metatdata
to the admin section.

Change-Id: I6d9dec56890fb3a9bc0539c45c43233517cea048
2017-10-18 15:55:24 -04:00

5.9 KiB
Raw Blame History

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