ceph/doc/cephfs/mount-using-fuse.rst
Jos Collin 86f8fa19e5
doc: document the relevance of mds_namespace mount option
Fixes: https://tracker.ceph.com/issues/57673
Signed-off-by: Jos Collin <jcollin@redhat.com>
2023-01-10 14:48:20 +05:30

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========================
Mount CephFS using FUSE
========================
`ceph-fuse`_ is an alternate way of mounting CephFS, although it mounts it
in userspace. Therefore, performance of FUSE can be relatively lower but FUSE
clients can be more manageable, especially while upgrading CephFS.
Prerequisites
=============
Go through the prerequisites required by both, kernel as well as FUSE mounts,
in `Mount CephFS: Prerequisites`_ page.
.. note:: Mounting CephFS using FUSE requires superuser privileges to trim dentries
by issuing a remount of itself.
Synopsis
========
In general, the command to mount CephFS via FUSE looks like this::
ceph-fuse {mountpoint} {options}
Mounting CephFS
===============
To FUSE-mount the Ceph file system, use the ``ceph-fuse`` command::
mkdir /mnt/mycephfs
ceph-fuse --id foo /mnt/mycephfs
Option ``-id`` passes the name of the CephX user whose keyring we intend to
use for mounting CephFS. In the above command, it's ``foo``. You can also use
``-n`` instead, although ``--id`` is evidently easier::
ceph-fuse -n client.foo /mnt/mycephfs
In case the keyring is not present in standard locations, you may pass it
too::
ceph-fuse --id foo -k /path/to/keyring /mnt/mycephfs
You may pass the MON's socket too, although this is not mandatory::
ceph-fuse --id foo -m 192.168.0.1:6789 /mnt/mycephfs
You can also mount a specific directory within CephFS instead of mounting
root of CephFS on your local FS::
ceph-fuse --id foo -r /path/to/dir /mnt/mycephfs
If you have more than one FS on your Ceph cluster, use the option
``--client_fs`` to mount the non-default FS::
ceph-fuse --id foo --client_fs mycephfs2 /mnt/mycephfs2
You may also add a ``client_fs`` setting to your ``ceph.conf``. Alternatively, the option
``--client_mds_namespace`` is supported for backward compatibility.
Unmounting CephFS
=================
Use ``umount`` to unmount CephFS like any other FS::
umount /mnt/mycephfs
.. tip:: Ensure that you are not within the file system directories before
executing this command.
Persistent Mounts
=================
To mount CephFS as a file system in user space, add the following to ``/etc/fstab``::
#DEVICE PATH TYPE OPTIONS
none /mnt/mycephfs fuse.ceph ceph.id={user-ID}[,ceph.conf={path/to/conf.conf}],_netdev,defaults 0 0
For example::
none /mnt/mycephfs fuse.ceph ceph.id=myuser,_netdev,defaults 0 0
none /mnt/mycephfs fuse.ceph ceph.id=myuser,ceph.conf=/etc/ceph/foo.conf,_netdev,defaults 0 0
Ensure you use the ID (e.g., ``myuser``, not ``client.myuser``). You can pass
any valid ``ceph-fuse`` option to the command line this way.
To mount a subdirectory of the CephFS, add the following to ``/etc/fstab``::
none /mnt/mycephfs fuse.ceph ceph.id=myuser,ceph.client_mountpoint=/path/to/dir,_netdev,defaults 0 0
``ceph-fuse@.service`` and ``ceph-fuse.target`` systemd units are available.
As usual, these unit files declare the default dependencies and recommended
execution context for ``ceph-fuse``. After making the fstab entry shown above,
run following commands::
systemctl start ceph-fuse@/mnt/mycephfs.service
systemctl enable ceph-fuse.target
systemctl enable ceph-fuse@-mnt-mycephfs.service
See :ref:`User Management <user-management>` for details on CephX user management and `ceph-fuse`_
manual for more options it can take. For troubleshooting, see
:ref:`ceph_fuse_debugging`.
.. _ceph-fuse: ../../man/8/ceph-fuse/#options
.. _Mount CephFS\: Prerequisites: ../mount-prerequisites