import ceph quincy 17.2.1

[ceph.git] / ceph / doc / rbd / rbd-persistent-write-log-cache.rst

diff --git a/ceph/doc/rbd/rbd-persistent-write-log-cache.rst b/ceph/doc/rbd/rbd-persistent-write-log-cache.rst
index ae3809ba3f85859a9335c46685b9c5c0a2f9148c..d1814a923b507e6e4395deb05accc2a627a573ec 100644 (file)
--- a/ceph/doc/rbd/rbd-persistent-write-log-cache.rst
+++ b/ceph/doc/rbd/rbd-persistent-write-log-cache.rst
@@ -60,10 +60,6 @@ Here are some cache configuration settings:
 - ``rbd_persistent_cache_size`` The cache size per image. The minimum cache
   size is 1 GB.
 
-- ``rbd_persistent_cache_log_periodic_stats`` This is a debug option. It is
-  used to emit periodic perf stats to the debug log if ``debug rbd pwl`` is
-  set to ``1`` or higher.
-
 The above configurations can be set per-host, per-pool, per-image etc. Eg, to
 set per-host, add the overrides to the appropriate `section`_ in the host's
 ``ceph.conf`` file. To set per-pool, per-image, etc, please refer to the
@@ -79,30 +75,59 @@ users may use the command ``rbd status``.  ::
         rbd status {pool-name}/{image-name}
 
 The status of the cache is shown, including present, clean, cache size and the
-location. Currently the status is updated only at the time the cache is opened
-and closed and therefore may appear to be out of date (e.g. show that the cache
-is clean when it is actually dirty).
+location as well as some basic metrics.
 
 For example::
 
         $ rbd status rbd/foo
-        Watchers: none
-        Image cache state: {"present":"true","empty":"false","clean":"true","cache_type":"ssd","pwl_host":"sceph9","pwl_path":"/tmp/rbd-pwl.rbd.abcdef123456.pool","pwl_size":1073741824}
+        Watchers:
+                watcher=10.10.0.102:0/1061883624 client.25496 cookie=140338056493088
+        Persistent cache state:
+                host: sceph9
+                path: /mnt/nvme0/rbd-pwl.rbd.101e5824ad9a.pool
+                size: 1 GiB
+                mode: ssd
+                stats_timestamp: Sun Apr 10 13:26:32 2022
+                present: true   empty: false    clean: false
+                allocated: 509 MiB
+                cached: 501 MiB
+                dirty: 338 MiB
+                free: 515 MiB
+                hits_full: 1450 / 61%
+                hits_partial: 0 / 0%
+                misses: 924
+                hit_bytes: 192 MiB / 66%
+                miss_bytes: 97 MiB
+
+Flush Cache
+-----------
+
+To flush a cache file with ``rbd``, specify the ``persistent-cache flush``
+command, the pool name and the image name.  ::
+
+        rbd persistent-cache flush {pool-name}/{image-name}
+
+If the application dies unexpectedly, this command can also be used to flush
+the cache back to OSDs.
+
+For example::
+
+        $ rbd persistent-cache flush rbd/foo
 
-Discard Cache
--------------
+Invalidate Cache
+----------------
 
-To discard a cache file with ``rbd``, specify the ``image-cache invalidate``
-option, the pool name and the image name.  ::
+To invalidate (discard) a cache file with ``rbd``, specify the
+``persistent-cache invalidate`` command, the pool name and the image name.  ::
 
-        rbd image-cache invalidate {pool-name}/{image-name}
+        rbd persistent-cache invalidate {pool-name}/{image-name}
 
-The command removes the cache metadata of the corresponding image, disable
+The command removes the cache metadata of the corresponding image, disables
 the cache feature and deletes the local cache file if it exists.
 
 For example::
 
-        $ rbd image-cache invalidate rbd/foo
+        $ rbd persistent-cache invalidate rbd/foo
 
 .. _section: ../../rados/configuration/ceph-conf/#configuration-sections
 .. _commands: ../../man/8/rbd#commands