Rename peristent cache to persistent read-only cache.
Signed-off-by: Li, Xiaoyan <xiaoyan.li@intel.com>
Exclusive Locking <rbd-exclusive-locks>
Mirroring <rbd-mirroring>
Live-Migration <rbd-live-migration>
- Persistent Cache <rbd-persistent-cache>
+ Persistent Read-only Cache <rbd-persistent-read-only-cache>
Config Settings (librbd) <rbd-config-ref/>
RBD Replay <rbd-replay>
+++ /dev/null
-=======================
- RBD Persistent Cache
-=======================
-
-.. index:: Ceph Block Device; Persistent Cache
-
-Shared, Read-only Parent Image Cache
-====================================
-
-`Cloned RBD images`_ usually modify only a small fraction of the parent
-image. For example, in a VDI use-case, VMs are cloned from the same
-base image and initially differ only by hostname and IP address. During
-booting, all of these VMs read portions of the same parent
-image data. If we have a local cache of the parent
-image, this speeds up reads on the caching host. We also achieve
-reduction of client-to-cluster network traffic.
-RBD cache must be explicitly enabled in
-``ceph.conf``. The ``ceph-immutable-object-cache`` daemon is responsible for
-caching the parent content on the local disk, and future reads on that data
-will be serviced from the local cache.
-
-.. note:: RBD shared read-only parent image cache requires the Ceph Nautilus release or later.
-
-.. ditaa::
-
- +--------------------------------------------------------+
- | QEMU |
- +--------------------------------------------------------+
- | librbd (cloned images) |
- +-------------------+-+----------------------------------+
- | librados | | ceph--immutable--object--cache |
- +-------------------+ +----------------------------------+
- | OSDs/Mons | | local cached parent image |
- +-------------------+ +----------------------------------+
-
-
-Enable RBD Shared Read-only Parent Image Cache
-----------------------------------------------
-
-To enable RBD shared read-only parent image cache, the following Ceph settings
-need to added in the ``[client]`` `section`_ of your ``ceph.conf`` file::
-
- rbd parent cache enabled = true
- rbd plugins = parent_cache
-
-Immutable Object Cache Daemon
-=============================
-
-The ``ceph-immutable-object-cache`` daemon is responsible for caching parent
-image content within its local caching directory. For better performance it's
-recommended to use SSDs as the underlying storage.
-
-The key components of the daemon are:
-
-#. **Domain socket based IPC:** The daemon will listen on a local domain
- socket on start up and wait for connections from librbd clients.
-
-#. **LRU based promotion/demotion policy:** The daemon will maintain
- in-memory statistics of cache-hits on each cache file. It will demote the
- cold cache if capacity reaches to the configured threshold.
-
-#. **File-based caching store:** The daemon will maintain a simple file
- based cache store. On promotion the RADOS objects will be fetched from
- RADOS cluster and stored in the local caching directory.
-
-On opening each cloned rbd image, ``librbd`` will try to connect to the
-cache daemon through its Unix domain socket. Once successfully connected,
-``librbd`` will coordinate with the daemon on the subsequent reads.
-If there's a read that's not cached, the daemon will promote the RADOS object
-to local caching directory, so the next read on that object will be serviced
-from cache. The daemon also maintains simple LRU statistics so that under
-capacity pressure it will evict cold cache files as needed.
-
-Here are some important cache configuration settings:
-
-- ``immutable_object_cache_sock`` The path to the domain socket used for
- communication between librbd clients and the ceph-immutable-object-cache
- daemon.
-
-- ``immutable_object_cache_path`` The immutable object cache data directory.
-
-- ``immutable_object_cache_max_size`` The max size for immutable cache.
-
-- ``immutable_object_cache_watermark`` The high-water mark for the cache. If the
- capacity reaches this threshold the daemon will delete cold cache based
- on LRU statistics.
-
-The ``ceph-immutable-object-cache`` daemon is available within the optional
-``ceph-immutable-object-cache`` distribution package.
-
-.. important:: ``ceph-immutable-object-cache`` daemon requires the ability to
- connect RADOS clusters.
-
-``ceph-immutable-object-cache`` daemon should use a unique Ceph user ID.
-To `create a Ceph user`_, with ``ceph`` specify the ``auth get-or-create``
-command, user name, monitor caps, and OSD caps::
-
- ceph auth get-or-create client.ceph-immutable-object-cache.{unique id} mon 'allow r' osd 'profile rbd-read-only'
-
-The ``ceph-immutable-object-cache`` daemon can be managed by ``systemd`` by specifying the user
-ID as the daemon instance::
-
- systemctl enable ceph-immutable-object-cache@immutable-object-cache.{unique id}
-
-The ``ceph-immutable-object-cache`` can also be run in foreground by ``ceph-immutable-object-cache`` command::
-
- ceph-immutable-object-cache -f --log-file={log_path}
-
-.. _Cloned RBD Images: ../rbd-snapshot/#layering
-.. _section: ../../rados/configuration/ceph-conf/#configuration-sections
-.. _create a Ceph user: ../../rados/operations/user-management#add-a-user
-
--- /dev/null
+===============================
+ RBD Persistent Read-only Cache
+===============================
+
+.. index:: Ceph Block Device; Persistent Read-only Cache
+
+Shared, Read-only Parent Image Cache
+====================================
+
+`Cloned RBD images`_ usually modify only a small fraction of the parent
+image. For example, in a VDI use-case, VMs are cloned from the same
+base image and initially differ only by hostname and IP address. During
+booting, all of these VMs read portions of the same parent
+image data. If we have a local cache of the parent
+image, this speeds up reads on the caching host. We also achieve
+reduction of client-to-cluster network traffic.
+RBD cache must be explicitly enabled in
+``ceph.conf``. The ``ceph-immutable-object-cache`` daemon is responsible for
+caching the parent content on the local disk, and future reads on that data
+will be serviced from the local cache.
+
+.. note:: RBD shared read-only parent image cache requires the Ceph Nautilus release or later.
+
+.. ditaa::
+
+ +--------------------------------------------------------+
+ | QEMU |
+ +--------------------------------------------------------+
+ | librbd (cloned images) |
+ +-------------------+-+----------------------------------+
+ | librados | | ceph--immutable--object--cache |
+ +-------------------+ +----------------------------------+
+ | OSDs/Mons | | local cached parent image |
+ +-------------------+ +----------------------------------+
+
+
+Enable RBD Shared Read-only Parent Image Cache
+----------------------------------------------
+
+To enable RBD shared read-only parent image cache, the following Ceph settings
+need to added in the ``[client]`` `section`_ of your ``ceph.conf`` file::
+
+ rbd parent cache enabled = true
+ rbd plugins = parent_cache
+
+Immutable Object Cache Daemon
+=============================
+
+The ``ceph-immutable-object-cache`` daemon is responsible for caching parent
+image content within its local caching directory. For better performance it's
+recommended to use SSDs as the underlying storage.
+
+The key components of the daemon are:
+
+#. **Domain socket based IPC:** The daemon will listen on a local domain
+ socket on start up and wait for connections from librbd clients.
+
+#. **LRU based promotion/demotion policy:** The daemon will maintain
+ in-memory statistics of cache-hits on each cache file. It will demote the
+ cold cache if capacity reaches to the configured threshold.
+
+#. **File-based caching store:** The daemon will maintain a simple file
+ based cache store. On promotion the RADOS objects will be fetched from
+ RADOS cluster and stored in the local caching directory.
+
+On opening each cloned rbd image, ``librbd`` will try to connect to the
+cache daemon through its Unix domain socket. Once successfully connected,
+``librbd`` will coordinate with the daemon on the subsequent reads.
+If there's a read that's not cached, the daemon will promote the RADOS object
+to local caching directory, so the next read on that object will be serviced
+from cache. The daemon also maintains simple LRU statistics so that under
+capacity pressure it will evict cold cache files as needed.
+
+Here are some important cache configuration settings:
+
+- ``immutable_object_cache_sock`` The path to the domain socket used for
+ communication between librbd clients and the ceph-immutable-object-cache
+ daemon.
+
+- ``immutable_object_cache_path`` The immutable object cache data directory.
+
+- ``immutable_object_cache_max_size`` The max size for immutable cache.
+
+- ``immutable_object_cache_watermark`` The high-water mark for the cache. If the
+ capacity reaches this threshold the daemon will delete cold cache based
+ on LRU statistics.
+
+The ``ceph-immutable-object-cache`` daemon is available within the optional
+``ceph-immutable-object-cache`` distribution package.
+
+.. important:: ``ceph-immutable-object-cache`` daemon requires the ability to
+ connect RADOS clusters.
+
+``ceph-immutable-object-cache`` daemon should use a unique Ceph user ID.
+To `create a Ceph user`_, with ``ceph`` specify the ``auth get-or-create``
+command, user name, monitor caps, and OSD caps::
+
+ ceph auth get-or-create client.ceph-immutable-object-cache.{unique id} mon 'allow r' osd 'profile rbd-read-only'
+
+The ``ceph-immutable-object-cache`` daemon can be managed by ``systemd`` by specifying the user
+ID as the daemon instance::
+
+ systemctl enable ceph-immutable-object-cache@immutable-object-cache.{unique id}
+
+The ``ceph-immutable-object-cache`` can also be run in foreground by ``ceph-immutable-object-cache`` command::
+
+ ceph-immutable-object-cache -f --log-file={log_path}
+
+.. _Cloned RBD Images: ../rbd-snapshot/#layering
+.. _section: ../../rados/configuration/ceph-conf/#configuration-sections
+.. _create a Ceph user: ../../rados/operations/user-management#add-a-user
+
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