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78 lines
2.4 KiB
ReStructuredText
78 lines
2.4 KiB
ReStructuredText
========================
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Create a Ceph filesystem
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========================
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Creating pools
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==============
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A Ceph filesystem requires at least two RADOS pools, one for data and one for metadata.
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When configuring these pools, you might consider:
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- Using a higher replication level for the metadata pool, as any data
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loss in this pool can render the whole filesystem inaccessible.
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- Using lower-latency storage such as SSDs for the metadata pool, as this
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will directly affect the observed latency of filesystem operations
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on clients.
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Refer to :doc:`/rados/operations/pools` to learn more about managing pools. For
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example, to create two pools with default settings for use with a filesystem, you
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might run the following commands:
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.. code:: bash
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$ ceph osd pool create cephfs_data <pg_num>
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$ ceph osd pool create cephfs_metadata <pg_num>
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Creating a filesystem
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=====================
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Once the pools are created, you may enable the filesystem using the ``fs new`` command:
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.. code:: bash
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$ ceph fs new <fs_name> <metadata> <data>
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For example:
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.. code:: bash
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$ ceph fs new cephfs cephfs_metadata cephfs_data
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$ ceph fs ls
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name: cephfs, metadata pool: cephfs_metadata, data pools: [cephfs_data ]
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Once a filesystem has been created, your MDS(s) will be able to enter
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an *active* state. For example, in a single MDS system:
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.. code:: bash
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$ ceph mds stat
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cephfs-1/1/1 up {0=a=up:active}
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Once the filesystem is created and the MDS is active, you are ready to mount
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the filesystem. If you have created more than one filesystem, you will
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choose which to use when mounting.
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- `Mount CephFS`_
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- `Mount CephFS as FUSE`_
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.. _Mount CephFS: ../../cephfs/kernel
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.. _Mount CephFS as FUSE: ../../cephfs/fuse
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If you have created more than one filesystem, and a client does not
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specify a filesystem when mounting, you can control which filesystem
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they will see by using the `ceph fs set-default` command.
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Using Erasure Coded pools with CephFS
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=====================================
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You may use Erasure Coded pools as CephFS data pools as long as they have overwrites enabled, which is done as follows:
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.. code:: bash
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ceph osd pool set my_ec_pool allow_ec_overwrites true
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Note that EC overwrites are only supported when using OSDS with the BlueStore backend.
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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.
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