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manila/doc/source/configuration/shared-file-systems/drivers/zfs-on-linux-driver.rst

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ZFS (on Linux) driver

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

Requirements

  • NFS daemon that can be handled through exportfs app.
  • ZFS file system 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 shared filesystems and operations

The driver supports NFS shares.

The following operations are supported:

  • Create a share.
  • Delete a share.
  • Allow share access.
    • Only IP access type is supported.
    • Both access levels are supported - RW and RO.
  • Deny share access.
  • Bring an existing ZFSOnLinux share under the shared file system service (Managing a share)
  • Remove a ZFSOnLinux share from the shared file system service without deleting it (Unmanaging a share)
  • Create a snapshot.
  • Delete a snapshot.
  • Bring an existing ZFSOnLinux snapshot under the shared file system service (Managing a snapshot)
  • Remove a ZFSOnLinux snapshot from the shared file system service without deleting it (Unmanaging a snapshot)
  • Create a share from snapshot.
  • Extend a share.
  • Shrink a share.
  • Share replication (experimental):
    • Create, update, delete, and promote replica operations are supported.

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 read-write.
  • All share replicas are synchronized periodically, not continuously. Status in_sync means latest sync was successful. Time range between syncs equals to the value of the replica_state_update_interval configuration global option.
  • Driver can use qualified extra spec zfsonlinux:compression. It can contain any value that ZFS app supports. But if it is disabled through the configuration option with the 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.
  • The below items are not yet implemented:
    • SaMBa based sharing.
    • Thick provisioning capability.

Known problems

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

Back-end configuration

The following parameters need to be configured in the manila configuration file for back-ends that use 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 back ends with the 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 SSHing to ZFS host ifzfs_use_sshis set toTrue``.
  • 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 drivers.
    • 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.

Driver options