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Taikun OCP Guide

Table of Contents

GlusterFS driver

GlusterFS driver uses GlusterFS, an open source distributed file
system, as the storage backend for serving file shares to manila
clients.

Supported shared filesystems

  • NFS (access by IP)

Supported Operations

  • Create share
  • Delete share
  • Allow share access (rw)
  • Deny share access
  • With volume layout:
    • Create snapshot
    • Delete snapshot
    • Create share from snapshot

Requirements

  • Install glusterfs-server package, version >= 3.5.x, on the
    storage backend.
  • Install NFS-Ganesha, version >=2.1, if using NFS-Ganesha as the
    NFS server for the GlusterFS backend.
  • Install glusterfs and glusterfs-fuse package, version >=3.5.x, on
    the manila host.
  • Establish network connection between the manila host and the storage
    backend.

Manila driver configuration
setting

The following parameters in the manila’s configuration file need to
be set:

  • share_driver =
    manila.share.drivers.glusterfs.GlusterfsShareDriver

The following configuration parameters are optional:

  • glusterfs_nfs_server_type = <NFS
    server type used by the GlusterFS

    backend, Gluster or Ganesha. Gluster
    is the default type>

  • glusterfs_share_layout = <share
    layout used>; cf. glusterfs_layouts
  • glusterfs_path_to_private_key =
    <path to manila host’s private key file>
  • glusterfs_server_password =
    <password of remote GlusterFS server machine>

If Ganesha NFS server is used
(glusterfs_nfs_server_type = Ganesha), then by default the
Ganesha server is supposed to run on the manila host and is managed by
local commands. If it’s deployed somewhere else, then it’s managed via
ssh, which can be configured by the following parameters:

  • glusterfs_ganesha_server_ip
  • glusterfs_ganesha_server_username
  • glusterfs_ganesha_server_password

In lack of glusterfs_ganesha_server_password ssh access
will fall back to key based authentication, using the key specified by
glusterfs_path_to_private_key, or, in lack of that, a key
at one of the OpenSSH-style default key locations
(~/.ssh/id_{r,d,ecd}sa).

Layouts have also their set of parameters, see glusterfs_layouts about
that.

Layouts

New in Liberty, multiple share layouts can be used with glusterfs
driver. A layout is a strategy of allocating storage from GlusterFS
backends for shares. Currently there are two layouts implemented:

  • directory mapped layout (or directory layout, or dir layout for short): a share is backed by
    top-level subdirectories of a given GlusterFS volume.

    Directory mapped layout is the default and backward compatible with
    Kilo. The following setting explicitly specifies its usage:
    glusterfs_share_layout = layout_directory.GlusterfsDirectoryMappedLayout.

    Options:

    • `glusterfs_target`: address of the volume that hosts the
      directories. If it’s of the format <glustervolserver>:/<glustervolid>,
      then the manila host is expected to be part of the GlusterFS cluster of
      the volume and GlusterFS management happens through locally calling the
      gluster utility. If it’s of the format <username>@<glustervolserver>:/<glustervolid>,
      then we ssh to <username>@<glustervolserver> to
      execute gluster (<username> is supposed to have
      administrative privileges on <glustervolserver>).
    • glusterfs_mount_point_base = <base
      path of GlusterFS volume mounted on

      manila host> (optional; defaults to
      $state_path/mnt, where $state_path
      defaults to /var/lib/manila)

    Limitations:

    • directory layout does not support snapshot operations.
  • volume mapped layout (or volume layout, or vol
    layout
    for short): a share is backed by a whole GlusterFS
    volume.

    Volume mapped layout is new in Liberty. It can be chosen by setting
    glusterfs_share_layout = layout_volume.GlusterfsVolumeMappedLayout.

    Options (required):

    • glusterfs_servers
    • glusterfs_volume_pattern

    Volume mapped layout is implemented as a common backend of the
    glusterfs and glusterfs-native drivers; see the description of these
    options in glusterfs_native_driver: gluster_native_manila_conf.

Gluster NFS with volume
mapped layout

A special configuration choice is

glusterfs_nfs_server_type = Gluster
glusterfs_share_layout = layout_volume.GlusterfsVolumeMappedLayout

that is, Gluster NFS used to export whole volumes.

All other GlusterFS backend configurations (including GlusterFS set
up with glusterfs-native) require the
nfs.export-volumes = off GlusterFS setting. Gluster NFS
with volume layout requires nfs.export-volumes = on.
nfs.export-volumes is a cluster-wide setting, so a
given GlusterFS cluster cannot host a share backend with Gluster NFS +
volume layout and other share backend configurations at the same
time.

There is another caveat with nfs.export-volumes: setting
it to on without enough care is a security risk, as the
default access control for the volume exports is “allow all”. For this
reason, while the nfs.export-volumes = off setting is
automatically set by manila for all other share backend configurations,
nfs.export-volumes = on is not set by manila in
case of a Gluster NFS with volume layout setup. It’s left to the
GlusterFS admin to make this setting in conjunction with the associated
safeguards (that is, for those volumes of the cluster which are not used
by manila, access restrictions have to be manually configured through
the nfs.rpc-auth-{allow,reject} options).

Known Restrictions

  • The driver does not support network segmented multi-tenancy model,
    but instead works over a flat network, where the tenants share a
    network.
  • If NFS Ganesha is the NFS server used by the GlusterFS backend, then
    the shares can be accessed by NFSv3 and v4 protocols. However, if
    Gluster NFS is used by the GlusterFS backend, then the shares can only
    be accessed by NFSv3 protocol.
  • All manila shares, which map to subdirectories within a GlusterFS
    volume, are currently created within a single GlusterFS volume of a
    GlusterFS storage pool.
  • The driver does not provide read-only access level for shares.
  • Assume that share S is exported through Gluster NFS, and tenant
    machine T has mounted S. If at this point access of T to S is revoked
    through access-deny, the pre-existing
    mount will be still usable and T will still be able to access the data
    in S as long as that mount is in place. (This violates the principle
    Access deny should always result in immediate loss of access to the
    share
    , see http://lists.openstack.org/pipermail/openstack-dev/2015-July/069109.html.)

The manila.share.drivers.glusterfs Module

manila.share.drivers.glusterfs

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