1 =====================================
2 Configuring Monitor/OSD Interaction
3 =====================================
7 After you have completed your initial Ceph configuration, you may deploy and run
8 Ceph. When you execute a command such as ``ceph health`` or ``ceph -s``, the
9 :term:`Ceph Monitor` reports on the current state of the :term:`Ceph Storage
10 Cluster`. The Ceph Monitor knows about the Ceph Storage Cluster by requiring
11 reports from each :term:`Ceph OSD Daemon`, and by receiving reports from Ceph
12 OSD Daemons about the status of their neighboring Ceph OSD Daemons. If the Ceph
13 Monitor doesn't receive reports, or if it receives reports of changes in the
14 Ceph Storage Cluster, the Ceph Monitor updates the status of the :term:`Ceph
17 Ceph provides reasonable default settings for Ceph Monitor/Ceph OSD Daemon
18 interaction. However, you may override the defaults. The following sections
19 describe how Ceph Monitors and Ceph OSD Daemons interact for the purposes of
20 monitoring the Ceph Storage Cluster.
22 .. index:: heartbeat interval
27 Each Ceph OSD Daemon checks the heartbeat of other Ceph OSD Daemons at random
28 intervals less than every 6 seconds. If a neighboring Ceph OSD Daemon doesn't
29 show a heartbeat within a 20 second grace period, the Ceph OSD Daemon may
30 consider the neighboring Ceph OSD Daemon ``down`` and report it back to a Ceph
31 Monitor, which will update the Ceph Cluster Map. You may change this grace
32 period by adding an ``osd heartbeat grace`` setting under the ``[mon]``
33 and ``[osd]`` or ``[global]`` section of your Ceph configuration file,
34 or by setting the value at runtime.
38 +---------+ +---------+
40 +---------+ +---------+
48 |------------------->|
50 |<-------------------|
59 |------------------->|
70 .. index:: OSD down report
75 By default, two Ceph OSD Daemons from different hosts must report to the Ceph
76 Monitors that another Ceph OSD Daemon is ``down`` before the Ceph Monitors
77 acknowledge that the reported Ceph OSD Daemon is ``down``. But there is chance
78 that all the OSDs reporting the failure are hosted in a rack with a bad switch
79 which has trouble connecting to another OSD. To avoid this sort of false alarm,
80 we consider the peers reporting a failure a proxy for a potential "subcluster"
81 over the overall cluster that is similarly laggy. This is clearly not true in
82 all cases, but will sometimes help us localize the grace correction to a subset
83 of the system that is unhappy. ``mon osd reporter subtree level`` is used to
84 group the peers into the "subcluster" by their common ancestor type in CRUSH
85 map. By default, only two reports from different subtree are required to report
86 another Ceph OSD Daemon ``down``. You can change the number of reporters from
87 unique subtrees and the common ancestor type required to report a Ceph OSD
88 Daemon ``down`` to a Ceph Monitor by adding an ``mon osd min down reporters``
89 and ``mon osd reporter subtree level`` settings under the ``[mon]`` section of
90 your Ceph configuration file, or by setting the value at runtime.
95 +---------+ +---------+ +---------+
96 | OSD 1 | | OSD 2 | | Monitor |
97 +---------+ +---------+ +---------+
100 |---------------+--------------->|
112 .. index:: peering failure
114 OSDs Report Peering Failure
115 ===========================
117 If a Ceph OSD Daemon cannot peer with any of the Ceph OSD Daemons defined in its
118 Ceph configuration file (or the cluster map), it will ping a Ceph Monitor for
119 the most recent copy of the cluster map every 30 seconds. You can change the
120 Ceph Monitor heartbeat interval by adding an ``osd mon heartbeat interval``
121 setting under the ``[osd]`` section of your Ceph configuration file, or by
122 setting the value at runtime.
126 +---------+ +---------+ +-------+ +---------+
127 | OSD 1 | | OSD 2 | | OSD 3 | | Monitor |
128 +---------+ +---------+ +-------+ +---------+
132 |-------------->| | |
133 |<--------------| | |
138 |----------------------------->| |
142 |<---+ Interval Exceeded |
144 | Failed to Peer with OSD 3 |
145 |-------------------------------------------->|
146 |<--------------------------------------------|
147 | Receive New Cluster Map |
150 .. index:: OSD status
152 OSDs Report Their Status
153 ========================
155 If an Ceph OSD Daemon doesn't report to a Ceph Monitor, the Ceph Monitor will
156 consider the Ceph OSD Daemon ``down`` after the ``mon osd report timeout``
157 elapses. A Ceph OSD Daemon sends a report to a Ceph Monitor when a reportable
158 event such as a failure, a change in placement group stats, a change in
159 ``up_thru`` or when it boots within 5 seconds. You can change the Ceph OSD
160 Daemon minimum report interval by adding an ``osd mon report interval``
161 setting under the ``[osd]`` section of your Ceph configuration file, or by
162 setting the value at runtime. A Ceph OSD Daemon sends a report to a Ceph
163 Monitor every 120 seconds irrespective of whether any notable changes occur.
164 You can change the Ceph Monitor report interval by adding an ``osd mon report
165 interval max`` setting under the ``[osd]`` section of your Ceph configuration
166 file, or by setting the value at runtime.
171 +---------+ +---------+
172 | OSD 1 | | Monitor |
173 +---------+ +---------+
185 |------------------->|
193 |------------------->|
209 Configuration Settings
210 ======================
212 When modifying heartbeat settings, you should include them in the ``[global]``
213 section of your configuration file.
215 .. index:: monitor heartbeat
220 .. confval:: mon_osd_min_up_ratio
221 .. confval:: mon_osd_min_in_ratio
222 .. confval:: mon_osd_laggy_halflife
223 .. confval:: mon_osd_laggy_weight
224 .. confval:: mon_osd_laggy_max_interval
225 .. confval:: mon_osd_adjust_heartbeat_grace
226 .. confval:: mon_osd_adjust_down_out_interval
227 .. confval:: mon_osd_auto_mark_in
228 .. confval:: mon_osd_auto_mark_auto_out_in
229 .. confval:: mon_osd_auto_mark_new_in
230 .. confval:: mon_osd_down_out_interval
231 .. confval:: mon_osd_down_out_subtree_limit
232 .. confval:: mon_osd_report_timeout
233 .. confval:: mon_osd_min_down_reporters
234 .. confval:: mon_osd_reporter_subtree_level
236 .. index:: OSD hearbeat
241 .. confval:: osd_heartbeat_interval
242 .. confval:: osd_heartbeat_grace
243 .. confval:: osd_mon_heartbeat_interval
244 .. confval:: osd_mon_heartbeat_stat_stale
245 .. confval:: osd_mon_report_interval
projects / ceph.git / blob