[ceph.git] / ceph / doc / rados / configuration / mon-osd-interaction.rst

=====================================
 Configuring Monitor/OSD Interaction
=====================================

.. index:: heartbeat

After you have completed your initial Ceph configuration, you may deploy and run
Ceph.  When you execute a command such as ``ceph health`` or ``ceph -s``,  the
:term:`Ceph Monitor` reports on the current state of the :term:`Ceph Storage
Cluster`. The Ceph Monitor knows about the Ceph Storage Cluster by requiring
reports from each :term:`Ceph OSD Daemon`, and by receiving reports from Ceph
OSD Daemons about the status of their neighboring Ceph OSD Daemons. If the Ceph
Monitor doesn't receive reports, or if it receives reports of changes in the
Ceph Storage Cluster, the Ceph Monitor updates the status of the :term:`Ceph
Cluster Map`.

Ceph provides reasonable default settings for Ceph Monitor/Ceph OSD Daemon
interaction. However, you may override the defaults. The following sections
describe how Ceph Monitors and Ceph OSD Daemons interact for the purposes of
monitoring the Ceph Storage Cluster.

.. index:: heartbeat interval

OSDs Check Heartbeats
=====================

Each Ceph OSD Daemon checks the heartbeat of other Ceph OSD Daemons every 6
seconds. You can change the heartbeat interval by adding an ``osd heartbeat
interval`` setting under the ``[osd]`` section of your Ceph configuration file,
or by setting the value at runtime. If a neighboring Ceph OSD Daemon doesn't
show a heartbeat within a 20 second grace period, the Ceph OSD Daemon may
consider the neighboring Ceph OSD Daemon ``down`` and report it back to a Ceph
Monitor, which will update the Ceph Cluster Map. You may change this grace
period by adding an ``osd heartbeat grace`` setting under the ``[mon]``
and ``[osd]`` or ``[global]`` section of your Ceph configuration file,
or by setting the value at runtime.


.. ditaa:: +---------+          +---------+
           |  OSD 1  |          |  OSD 2  |
           +---------+          +---------+
                |                    |
                |----+ Heartbeat     |
                |    | Interval      |
                |<---+ Exceeded      |
                |                    |
                |       Check        |
                |     Heartbeat      |
                |------------------->|
                |                    |
                |<-------------------|
                |   Heart Beating    |
                |                    |
                |----+ Heartbeat     |
                |    | Interval      |
                |<---+ Exceeded      |
                |                    |
                |       Check        |
                |     Heartbeat      |
                |------------------->|
                |                    |
                |----+ Grace         |
                |    | Period        |
                |<---+ Exceeded      |
                |                    |
                |----+ Mark          |
                |    | OSD 2         |
                |<---+ Down          |
                

.. index:: OSD down report

OSDs Report Down OSDs
=====================

By default, a Ceph OSD Daemon must report to the Ceph Monitors that another Ceph
OSD Daemon is ``down`` three times before the Ceph Monitors acknowledge that the
reported Ceph OSD Daemon is ``down``. By default, only one
Ceph OSD Daemon is required to report another Ceph OSD Daemon ``down``. You can
change the number of Ceph OSD Daemones required to report a Ceph OSD Daemon
``down`` to a Ceph Monitor by adding an ``mon osd min down reporters`` setting
(``osd min down reporters`` prior to v0.62) under the ``[mon]`` section of your
Ceph configuration file, or by setting the value at runtime.


.. ditaa:: +---------+     +---------+
           |  OSD 1  |     | Monitor |
           +---------+     +---------+
                |               |             
                | OSD 2 Is Down |
                |-------------->|
                |               |             
                | OSD 2 Is Down |
                |-------------->|
                |               |             
                | OSD 2 Is Down |
                |-------------->|
                |               |             
                |               |----------+ Mark
                |               |          | OSD 2                
                |               |<---------+ Down


.. index:: peering failure

OSDs Report Peering Failure
===========================

If a Ceph OSD Daemon cannot peer with any of the Ceph OSD Daemons defined in its
Ceph configuration file (or the cluster map), it will ping a Ceph Monitor for
the most recent copy of the cluster map every 30 seconds. You can change the
Ceph Monitor heartbeat interval by adding an ``osd mon heartbeat interval``
setting under the ``[osd]`` section of your Ceph configuration file, or by
setting the value at runtime.

.. ditaa:: +---------+     +---------+     +-------+     +---------+
           |  OSD 1  |     |  OSD 2  |     | OSD 3 |     | Monitor |
           +---------+     +---------+     +-------+     +---------+
                |               |              |              |
                |  Request To   |              |              |
                |     Peer      |              |              |               
                |-------------->|              |              |
                |<--------------|              |              |
                |    Peering                   |              |
                |                              |              |
                |  Request To                  |              |
                |     Peer                     |              |               
                |----------------------------->|              |
                |                                             |
                |----+ OSD Monitor                            |
                |    | Heartbeat                              |
                |<---+ Interval Exceeded                      |
                |                                             |
                |         Failed to Peer with OSD 3           |
                |-------------------------------------------->|
                |<--------------------------------------------|
                |          Receive New Cluster Map            |
 

.. index:: OSD status

OSDs Report Their Status
========================

If an Ceph OSD Daemon doesn't report to a Ceph Monitor, the Ceph Monitor will
consider the Ceph OSD Daemon ``down`` after the  ``mon osd report timeout``
elapses. A Ceph OSD Daemon sends a report to a Ceph Monitor when a reportable
event such as a failure, a change in placement group stats, a change in
``up_thru`` or when it boots within 5 seconds. You can change the Ceph OSD
Daemon minimum report interval by adding an ``osd mon report interval min``
setting under the ``[osd]`` section of your Ceph configuration file, or by
setting the value at runtime. A Ceph OSD Daemon sends a report to a Ceph 
Monitor every 120 seconds irrespective of whether any notable changes occur. 
You can change the Ceph Monitor report interval by adding an ``osd mon report 
interval max`` setting under the ``[osd]`` section of your Ceph configuration 
file, or by setting the value at runtime.


.. ditaa:: +---------+          +---------+
           |  OSD 1  |          | Monitor |
           +---------+          +---------+
                |                    |
                |----+ Report Min    |
                |    | Interval      |
                |<---+ Exceeded      |
                |                    |
                |----+ Reportable    |
                |    | Event         |
                |<---+ Occurs        |
                |                    |
                |     Report To      |
                |      Monitor       |
                |------------------->|
                |                    |
                |----+ Report Max    |
                |    | Interval      |
                |<---+ Exceeded      |
                |                    |
                |     Report To      |
                |      Monitor       |
                |------------------->|
                |                    |
                |----+ Monitor       |
                |    | Fails         |
                |<---+               |
                                     +----+ Monitor OSD
                                     |    | Report Timeout
                                     |<---+ Exceeded
                                     |
                                     +----+ Mark
                                     |    | OSD 1
                                     |<---+ Down


Configuration Settings
======================

When modifying heartbeat settings, you should include them in the ``[global]``
section of your configuration file.

.. index:: monitor heartbeat

Monitor Settings
----------------

``mon osd min up ratio``

:Description: The minimum ratio of ``up`` Ceph OSD Daemons before Ceph will 
              mark Ceph OSD Daemons ``down``.
              
:Type: Double
:Default: ``.3``


``mon osd min in ratio``

:Description: The minimum ratio of ``in`` Ceph OSD Daemons before Ceph will 
              mark Ceph OSD Daemons ``out``.
              
:Type: Double
:Default: ``.75``


``mon osd laggy halflife``

:Description: The number of seconds laggy estimates will decay.
:Type: Integer
:Default: ``60*60``


``mon osd laggy weight``

:Description: The weight for new samples in laggy estimation decay.
:Type: Double
:Default: ``0.3``


``mon osd adjust heartbeat grace``

:Description: If set to ``true``, Ceph will scale based on laggy estimations.
:Type: Boolean
:Default: ``true``


``mon osd adjust down out interval``

:Description: If set to ``true``, Ceph will scaled based on laggy estimations.
:Type: Boolean
:Default: ``true``


``mon osd auto mark in`` 

:Description: Ceph will mark any booting Ceph OSD Daemons as ``in`` 
              the Ceph Storage Cluster.

:Type: Boolean
:Default: ``false``


``mon osd auto mark auto out in`` 

:Description: Ceph will mark booting Ceph OSD Daemons auto marked ``out`` 
              of the Ceph Storage Cluster as ``in`` the cluster.
              
:Type: Boolean
:Default: ``true`` 


``mon osd auto mark new in`` 

:Description: Ceph will mark booting new Ceph OSD Daemons as ``in`` the 
              Ceph Storage Cluster.
              
:Type: Boolean
:Default: ``true`` 


``mon osd down out interval`` 

:Description: The number of seconds Ceph waits before marking a Ceph OSD Daemon
              ``down`` and ``out`` if it doesn't respond.
              
:Type: 32-bit Integer
:Default: ``600``


``mon osd down out subtree limit``

:Description: The smallest :term:`CRUSH` unit type that Ceph will **not**
              automatically mark out. For instance, if set to ``host`` and if
              all OSDs of a host are down, Ceph will not automatically mark out
              these OSDs.

:Type: String
:Default: ``rack``


``mon osd report timeout`` 

:Description: The grace period in seconds before declaring 
              unresponsive Ceph OSD Daemons ``down``.

:Type: 32-bit Integer
:Default: ``900``

``mon osd min down reporters`` 

:Description: The minimum number of Ceph OSD Daemons required to report a 
              ``down`` Ceph OSD Daemon.

:Type: 32-bit Integer
:Default: ``1``


.. index:: OSD hearbeat

OSD Settings
------------

``osd heartbeat address``

:Description: An Ceph OSD Daemon's network address for heartbeats. 
:Type: Address
:Default: The host address.


``osd heartbeat interval`` 

:Description: How often an Ceph OSD Daemon pings its peers (in seconds).
:Type: 32-bit Integer
:Default: ``6``


``osd heartbeat grace`` 

:Description: The elapsed time when a Ceph OSD Daemon hasn't shown a heartbeat
              that the Ceph Storage Cluster considers it ``down``.
              This setting has to be set in both the [mon] and [osd] or [global]
              section so that it is read by both the MON and OSD daemons.
 
:Type: 32-bit Integer
:Default: ``20``


``osd mon heartbeat interval`` 

:Description: How often the Ceph OSD Daemon pings a Ceph Monitor if it has no 
              Ceph OSD Daemon peers.

:Type: 32-bit Integer
:Default: ``30`` 


``osd mon report interval max`` 

:Description: The maximum time in seconds that a Ceph OSD Daemon can wait before
              it must report to a Ceph Monitor.

:Type: 32-bit Integer
:Default: ``120`` 


``osd mon report interval min`` 

:Description: The minimum number of seconds a Ceph OSD Daemon may wait
              from startup or another reportable event before reporting 
              to a Ceph Monitor.

:Type: 32-bit Integer
:Default: ``5``
:Valid Range: Should be less than ``osd mon report interval max`` 


``osd mon ack timeout`` 

:Description: The number of seconds to wait for a Ceph Monitor to acknowledge a 
              request for statistics.

:Type: 32-bit Integer
:Default: ``30``
Commit	Line	Data
7c673cae FG	1	=====================================
	2	Configuring Monitor/OSD Interaction
	3	=====================================
	4
	5	.. index:: heartbeat
	6
	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
	15	Cluster Map`.
	16
	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.
	21
	22	.. index:: heartbeat interval
	23
	24	OSDs Check Heartbeats
	25	=====================
	26
	27	Each Ceph OSD Daemon checks the heartbeat of other Ceph OSD Daemons every 6
	28	seconds. You can change the heartbeat interval by adding an ``osd heartbeat
	29	interval`` setting under the ``[osd]`` section of your Ceph configuration file,
	30	or by setting the value at runtime. If a neighboring Ceph OSD Daemon doesn't
	31	show a heartbeat within a 20 second grace period, the Ceph OSD Daemon may
	32	consider the neighboring Ceph OSD Daemon ``down`` and report it back to a Ceph
	33	Monitor, which will update the Ceph Cluster Map. You may change this grace
	34	period by adding an ``osd heartbeat grace`` setting under the ``[mon]``
	35	and ``[osd]`` or ``[global]`` section of your Ceph configuration file,
	36	or by setting the value at runtime.
	37
	38
	39	.. ditaa:: +---------+ +---------+
	40	\| OSD 1 \| \| OSD 2 \|
	41	+---------+ +---------+
	42	\| \|
	43	\|----+ Heartbeat \|
	44	\| \| Interval \|
	45	\|<---+ Exceeded \|
	46	\| \|
	47	\| Check \|
	48	\| Heartbeat \|
	49	\|------------------->\|
	50	\| \|
	51	\|<-------------------\|
	52	\| Heart Beating \|
	53	\| \|
	54	\|----+ Heartbeat \|
	55	\| \| Interval \|
	56	\|<---+ Exceeded \|
	57	\| \|
	58	\| Check \|
	59	\| Heartbeat \|
	60	\|------------------->\|
	61	\| \|
	62	\|----+ Grace \|
	63	\| \| Period \|
	64	\|<---+ Exceeded \|
65	\| \|
66	\|----+ Mark \|
67	\| \| OSD 2 \|
68	\|<---+ Down \|
69
70
71	.. index:: OSD down report
72
73	OSDs Report Down OSDs
74	=====================
75
76	By default, a Ceph OSD Daemon must report to the Ceph Monitors that another Ceph
77	OSD Daemon is ``down`` three times before the Ceph Monitors acknowledge that the
78	reported Ceph OSD Daemon is ``down``. By default, only one
79	Ceph OSD Daemon is required to report another Ceph OSD Daemon ``down``. You can
80	change the number of Ceph OSD Daemones required to report a Ceph OSD Daemon
81	``down`` to a Ceph Monitor by adding an ``mon osd min down reporters`` setting
82	(``osd min down reporters`` prior to v0.62) under the ``[mon]`` section of your
83	Ceph configuration file, or by setting the value at runtime.
84
85
86	.. ditaa:: +---------+ +---------+
87	\| OSD 1 \| \| Monitor \|
88	+---------+ +---------+
89	\| \|
90	\| OSD 2 Is Down \|
91	\|-------------->\|
92	\| \|
93	\| OSD 2 Is Down \|
94	\|-------------->\|
95	\| \|
96	\| OSD 2 Is Down \|
97	\|-------------->\|
98	\| \|
99	\| \|----------+ Mark
100	\| \| \| OSD 2
101	\| \|<---------+ Down
102
103
104	.. index:: peering failure
105
106	OSDs Report Peering Failure
107	===========================
108
109	If a Ceph OSD Daemon cannot peer with any of the Ceph OSD Daemons defined in its
110	Ceph configuration file (or the cluster map), it will ping a Ceph Monitor for
111	the most recent copy of the cluster map every 30 seconds. You can change the
112	Ceph Monitor heartbeat interval by adding an ``osd mon heartbeat interval``
113	setting under the ``[osd]`` section of your Ceph configuration file, or by
114	setting the value at runtime.
115
116	.. ditaa:: +---------+ +---------+ +-------+ +---------+
117	\| OSD 1 \| \| OSD 2 \| \| OSD 3 \| \| Monitor \|
118	+---------+ +---------+ +-------+ +---------+
119	\| \| \| \|
120	\| Request To \| \| \|
121	\| Peer \| \| \|
122	\|-------------->\| \| \|
123	\|<--------------\| \| \|
124	\| Peering \| \|
125	\| \| \|
126	\| Request To \| \|
127	\| Peer \| \|
128	\|----------------------------->\| \|
129	\| \|
130	\|----+ OSD Monitor \|
131	\| \| Heartbeat \|
132	\|<---+ Interval Exceeded \|
133	\| \|
134	\| Failed to Peer with OSD 3 \|
135	\|-------------------------------------------->\|
136	\|<--------------------------------------------\|
137	\| Receive New Cluster Map \|
138
139
140	.. index:: OSD status
141
142	OSDs Report Their Status
143	========================
144
145	If an Ceph OSD Daemon doesn't report to a Ceph Monitor, the Ceph Monitor will
146	consider the Ceph OSD Daemon ``down`` after the ``mon osd report timeout``
147	elapses. A Ceph OSD Daemon sends a report to a Ceph Monitor when a reportable
148	event such as a failure, a change in placement group stats, a change in
149	``up_thru`` or when it boots within 5 seconds. You can change the Ceph OSD
150	Daemon minimum report interval by adding an ``osd mon report interval min``
151	setting under the ``[osd]`` section of your Ceph configuration file, or by
152	setting the value at runtime. A Ceph OSD Daemon sends a report to a Ceph
153	Monitor every 120 seconds irrespective of whether any notable changes occur.
154	You can change the Ceph Monitor report interval by adding an ``osd mon report
155	interval max`` setting under the ``[osd]`` section of your Ceph configuration
156	file, or by setting the value at runtime.
157
158
159	.. ditaa:: +---------+ +---------+
160	\| OSD 1 \| \| Monitor \|
161	+---------+ +---------+
162	\| \|
163	\|----+ Report Min \|
164	\| \| Interval \|
165	\|<---+ Exceeded \|
166	\| \|
167	\|----+ Reportable \|
168	\| \| Event \|
169	\|<---+ Occurs \|
170	\| \|
171	\| Report To \|
172	\| Monitor \|
173	\|------------------->\|
174	\| \|
175	\|----+ Report Max \|
176	\| \| Interval \|
177	\|<---+ Exceeded \|
178	\| \|
179	\| Report To \|
180	\| Monitor \|
181	\|------------------->\|
182	\| \|
183	\|----+ Monitor \|
184	\| \| Fails \|
185	\|<---+ \|
186	+----+ Monitor OSD
187	\| \| Report Timeout
188	\|<---+ Exceeded
189	\|
190	+----+ Mark
191	\| \| OSD 1
192	\|<---+ Down
193
194
195
196
197	Configuration Settings
198	======================
199
200	When modifying heartbeat settings, you should include them in the ``[global]``
201	section of your configuration file.
202
203	.. index:: monitor heartbeat
204
205	Monitor Settings
206	----------------
207
208	``mon osd min up ratio``
209
210	:Description: The minimum ratio of ``up`` Ceph OSD Daemons before Ceph will
211	mark Ceph OSD Daemons ``down``.
212
213	:Type: Double
214	:Default: ``.3``
215
216
217	``mon osd min in ratio``
218
219	:Description: The minimum ratio of ``in`` Ceph OSD Daemons before Ceph will
220	mark Ceph OSD Daemons ``out``.
221
222	:Type: Double
223	:Default: ``.75``
224
225
226	``mon osd laggy halflife``
227
228	:Description: The number of seconds laggy estimates will decay.
229	:Type: Integer
230	:Default: ``60*60``
231
232
233	``mon osd laggy weight``
234
235	:Description: The weight for new samples in laggy estimation decay.
236	:Type: Double
237	:Default: ``0.3``
238
239
240	``mon osd adjust heartbeat grace``
241
242	:Description: If set to ``true``, Ceph will scale based on laggy estimations.
243	:Type: Boolean
244	:Default: ``true``
245
246
247	``mon osd adjust down out interval``
248
249	:Description: If set to ``true``, Ceph will scaled based on laggy estimations.
250	:Type: Boolean
251	:Default: ``true``
252
253
254	``mon osd auto mark in``
255
256	:Description: Ceph will mark any booting Ceph OSD Daemons as ``in``
257	the Ceph Storage Cluster.
258
259	:Type: Boolean
260	:Default: ``false``
261
262
263	``mon osd auto mark auto out in``
264
265	:Description: Ceph will mark booting Ceph OSD Daemons auto marked ``out``
266	of the Ceph Storage Cluster as ``in`` the cluster.
267
268	:Type: Boolean
269	:Default: ``true``
270
271
272	``mon osd auto mark new in``
273
274	:Description: Ceph will mark booting new Ceph OSD Daemons as ``in`` the
275	Ceph Storage Cluster.
276
277	:Type: Boolean
278	:Default: ``true``
279
280
281	``mon osd down out interval``
282
283	:Description: The number of seconds Ceph waits before marking a Ceph OSD Daemon
284	``down`` and ``out`` if it doesn't respond.
285
286	:Type: 32-bit Integer
287	:Default: ``600``
288
289
290	``mon osd down out subtree limit``
291
292	:Description: The smallest :term:`CRUSH` unit type that Ceph will not
293	automatically mark out. For instance, if set to ``host`` and if
294	all OSDs of a host are down, Ceph will not automatically mark out
295	these OSDs.
296
297	:Type: String
298	:Default: ``rack``
299
300
301	``mon osd report timeout``
302
303	:Description: The grace period in seconds before declaring
304	unresponsive Ceph OSD Daemons ``down``.
305
306	:Type: 32-bit Integer
307	:Default: ``900``
308
309	``mon osd min down reporters``
310
311	:Description: The minimum number of Ceph OSD Daemons required to report a
312	``down`` Ceph OSD Daemon.
313
314	:Type: 32-bit Integer
315	:Default: ``1``
316
317
318	.. index:: OSD hearbeat
319
320	OSD Settings
321	------------
322
323	``osd heartbeat address``
324
325	:Description: An Ceph OSD Daemon's network address for heartbeats.
326	:Type: Address
327	:Default: The host address.
328
329
330	``osd heartbeat interval``
331
332	:Description: How often an Ceph OSD Daemon pings its peers (in seconds).
333	:Type: 32-bit Integer
334	:Default: ``6``
335
336
337	``osd heartbeat grace``
338
339	:Description: The elapsed time when a Ceph OSD Daemon hasn't shown a heartbeat
340	that the Ceph Storage Cluster considers it ``down``.
341	This setting has to be set in both the [mon] and [osd] or [global]
342	section so that it is read by both the MON and OSD daemons.
343
344	:Type: 32-bit Integer
345	:Default: ``20``
346
347
348	``osd mon heartbeat interval``
349
350	:Description: How often the Ceph OSD Daemon pings a Ceph Monitor if it has no
351	Ceph OSD Daemon peers.
352
353	:Type: 32-bit Integer
354	:Default: ``30``
355
356
357	``osd mon report interval max``
358
359	:Description: The maximum time in seconds that a Ceph OSD Daemon can wait before
360	it must report to a Ceph Monitor.
361
362	:Type: 32-bit Integer
363	:Default: ``120``
364
365
366	``osd mon report interval min``
367
368	:Description: The minimum number of seconds a Ceph OSD Daemon may wait
369	from startup or another reportable event before reporting
370	to a Ceph Monitor.
371
372	:Type: 32-bit Integer
373	:Default: ``5``
374	:Valid Range: Should be less than ``osd mon report interval max``
375
376
377	``osd mon ack timeout``
378
379	:Description: The number of seconds to wait for a Ceph Monitor to acknowledge a
380	request for statistics.
381
382	:Type: 32-bit Integer
383	:Default: ``30``
384