common/config: Add description to (near)full ratio settings

For many users it is not clear that these only apply to initial creation
of the cluster and that afterwards these commands need to be used:

  ceph osd set-nearfull-ratio <float[0.0-1.0]>
  ceph osd set-full-ratio <float[0.0-1.0]>

Signed-off-by: Wido den Hollander <wido@42on.com>

diff --git a/doc/rados/configuration/mon-config-ref.rst b/doc/rados/configuration/mon-config-ref.rst
index 4cdd7889cfff29d05db9adeeef240197d8b083c5..e0e990c19cae4479c9a1a669acaf4d609ca5c418 100644 (file)
--- a/doc/rados/configuration/mon-config-ref.rst
+++ b/doc/rados/configuration/mon-config-ref.rst
@@ -520,6 +520,9 @@ you expect to fail to arrive at a reasonable full ratio. Repeat the foregoing
 process with a higher number of OSD failures (e.g., a rack of OSDs) to arrive at
 a reasonable number for a near full ratio.
 
+The following settings only apply on cluster creation and are then stored in
+the OSDMap.
+
 .. code-block:: ini
 
        [global]
@@ -559,6 +562,10 @@ a reasonable number for a near full ratio.
 .. tip:: If some OSDs are nearfull, but others have plenty of capacity, you 
          may have a problem with the CRUSH weight for the nearfull OSDs.
 
+.. tip:: These settings only apply during cluster creation. Afterwards they need
+         to be changed in the OSDMap using ``ceph osd set-nearfull-ratio`` and
+         ``ceph osd set-full-ratio``
+
 .. index:: heartbeat
 
 Heartbeat

diff --git a/doc/rados/troubleshooting/troubleshooting-osd.rst b/doc/rados/troubleshooting/troubleshooting-osd.rst
index 2ca5fdbe8b7015f0d1af71cdde21432c244fe6a8..d917e97d7ccfb151625055acb3c4e7ab9ed5d573 100644 (file)
--- a/doc/rados/troubleshooting/troubleshooting-osd.rst
+++ b/doc/rados/troubleshooting/troubleshooting-osd.rst
@@ -208,16 +208,29 @@ is getting near its full ratio. The ``mon osd full ratio`` defaults to
 ``0.95``, or 95% of capacity before it stops clients from writing data.
 The ``mon osd backfillfull ratio`` defaults to ``0.90``, or 90 % of
 capacity when it blocks backfills from starting. The
-``mon osd nearfull ratio`` defaults to ``0.85``, or 85% of capacity
+OSD nearfull ratio defaults to ``0.85``, or 85% of capacity
 when it generates a health warning.
 
+Changing it can be done using:
+
+::
+
+    ceph osd set-nearfull-ratio <float[0.0-1.0]>
+
+
 Full cluster issues usually arise when testing how Ceph handles an OSD
 failure on a small cluster. When one node has a high percentage of the
 cluster's data, the cluster can easily eclipse its nearfull and full ratio
 immediately. If you are testing how Ceph reacts to OSD failures on a small
 cluster, you should leave ample free disk space and consider temporarily
-lowering the ``mon osd full ratio``, ``mon osd backfillfull ratio``  and
-``mon osd nearfull ratio``.
+lowering the OSD ``full ratio``, OSD ``backfillfull ratio``  and
+OSD ``nearfull ratio`` using these commands:
+
+::
+
+    ceph osd set-nearfull-ratio <float[0.0-1.0]>
+    ceph osd set-full-ratio <float[0.0-1.0]>
+    ceph osd set-backfillfull-ratio <float[0.0-1.0]>
 
 Full ``ceph-osds`` will be reported by ``ceph health``::
 

diff --git a/src/common/options.cc b/src/common/options.cc
index 6ab65b1a8f6972ef6cc501dadb0dd7a9d5f606bd..d0052e3fbe6ec6c9520ce0d5a9605dd1d58c9107 100644 (file)
--- a/src/common/options.cc
+++ b/src/common/options.cc
@@ -1389,7 +1389,7 @@ std::vector<Option> get_global_options() {
     .set_default(.95)
     .set_flag(Option::FLAG_NO_MON_UPDATE)
     .set_flag(Option::FLAG_CLUSTER_CREATE)
-    .set_description(""),
+    .set_description("full ratio of OSDs to be set during initial creation of the cluster"),
 
     Option("mon_osd_backfillfull_ratio", Option::TYPE_FLOAT, Option::LEVEL_ADVANCED)
     .set_default(.90)
@@ -1401,7 +1401,7 @@ std::vector<Option> get_global_options() {
     .set_default(.85)
     .set_flag(Option::FLAG_NO_MON_UPDATE)
     .set_flag(Option::FLAG_CLUSTER_CREATE)
-    .set_description(""),
+    .set_description("nearfull ratio for OSDs to be set during initial creation of cluster"),
 
     Option("mon_osd_initial_require_min_compat_client", Option::TYPE_STR, Option::LEVEL_ADVANCED)
     .set_default("jewel")