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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:45:59 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:45:59 +0000 |
commit | 19fcec84d8d7d21e796c7624e521b60d28ee21ed (patch) | |
tree | 42d26aa27d1e3f7c0b8bd3fd14e7d7082f5008dc /doc/cephfs/createfs.rst | |
parent | Initial commit. (diff) | |
download | ceph-upstream.tar.xz ceph-upstream.zip |
Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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-rw-r--r-- | doc/cephfs/createfs.rst | 100 |
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diff --git a/doc/cephfs/createfs.rst b/doc/cephfs/createfs.rst new file mode 100644 index 000000000..537a46b25 --- /dev/null +++ b/doc/cephfs/createfs.rst @@ -0,0 +1,100 @@ +========================= +Create a Ceph file system +========================= + +Creating pools +============== + +A Ceph file system requires at least two RADOS pools, one for data and one for metadata. +When configuring these pools, you might consider: + +- Using a higher replication level for the metadata pool, as any data loss in + this pool can render the whole file system inaccessible. +- Using lower-latency storage such as SSDs for the metadata pool, as this will + directly affect the observed latency of file system operations on clients. +- The data pool used to create the file system is the "default" data pool and + the location for storing all inode backtrace information, used for hard link + management and disaster recovery. For this reason, all inodes created in + CephFS have at least one object in the default data pool. If erasure-coded + pools are planned for the file system, it is usually better to use a + replicated pool for the default data pool to improve small-object write and + read performance for updating backtraces. Separately, another erasure-coded + data pool can be added (see also :ref:`ecpool`) that can be used on an entire + hierarchy of directories and files (see also :ref:`file-layouts`). + +Refer to :doc:`/rados/operations/pools` to learn more about managing pools. For +example, to create two pools with default settings for use with a file system, you +might run the following commands: + +.. code:: bash + + $ ceph osd pool create cephfs_data + $ ceph osd pool create cephfs_metadata + +Generally, the metadata pool will have at most a few gigabytes of data. For +this reason, a smaller PG count is usually recommended. 64 or 128 is commonly +used in practice for large clusters. + +.. note:: The names of the file systems, metadata pools, and data pools can + only have characters in the set [a-zA-Z0-9\_-.]. + +Creating a file system +====================== + +Once the pools are created, you may enable the file system using the ``fs new`` command: + +.. code:: bash + + $ ceph fs new <fs_name> <metadata> <data> + +For example: + +.. code:: bash + + $ ceph fs new cephfs cephfs_metadata cephfs_data + $ ceph fs ls + name: cephfs, metadata pool: cephfs_metadata, data pools: [cephfs_data ] + +Once a file system has been created, your MDS(s) will be able to enter +an *active* state. For example, in a single MDS system: + +.. code:: bash + + $ ceph mds stat + cephfs-1/1/1 up {0=a=up:active} + +Once the file system is created and the MDS is active, you are ready to mount +the file system. If you have created more than one file system, you will +choose which to use when mounting. + + - `Mount CephFS`_ + - `Mount CephFS as FUSE`_ + - `Mount CephFS on Windows`_ + +.. _Mount CephFS: ../../cephfs/mount-using-kernel-driver +.. _Mount CephFS as FUSE: ../../cephfs/mount-using-fuse +.. _Mount CephFS on Windows: ../../cephfs/ceph-dokan + +If you have created more than one file system, and a client does not +specify a file system when mounting, you can control which file system +they will see by using the `ceph fs set-default` command. + +Adding a Data Pool to the File System +------------------------------------- + +See :ref:`adding-data-pool-to-file-system`. + + +Using Erasure Coded pools with CephFS +===================================== + +You may use Erasure Coded pools as CephFS data pools as long as they have overwrites enabled, which is done as follows: + +.. code:: bash + + ceph osd pool set my_ec_pool allow_ec_overwrites true + +Note that EC overwrites are only supported when using OSDS with the BlueStore backend. + +You may not use Erasure Coded pools as CephFS metadata pools, because CephFS metadata is stored using RADOS *OMAP* data structures, which EC pools cannot store. + |