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Chapter 2. Configuring Logging
This chapter describes how to configure logging for various Ceph subsystems.
Logging is resource intensive. Also, verbose logging can generate a huge amount of data in a relatively short time. It you are encountering problems in a specific subsystem of the cluster, enable logging only of that subsystem. See Section 2.1, “Ceph Subsystems” for more information.
In addition, consider setting up a rotation of log files. See Section 2.4, “Accelerating Log Rotation” for details.
Once you fix any problems you encounter, change the subsystems log and memory levels to their default values. See Appendix A, Subsystems Default Logging Levels Values for list of all Ceph subsystems and their default values.
You can configure Ceph logging by:
-
Using the
cephcommand at runtime. This is the most common approach. See Section 2.2, “Configuring Logging at Runtime” for details. - Updating the Ceph configuration file. Use this approach if you are encountering problems when starting the cluster. See Section 2.3, “Configuring Logging in the Ceph Configuration File” for details.
2.1. Ceph Subsystems
This section contains information about Ceph subsystems and their logging levels.
Understanding Ceph Subsystems and Their Logging Levels
Ceph consists of several subsystems. Each subsystem has a logging level of its:
-
Output logs that are stored by default in
/var/log/ceph/directory (log level) - Logs that are stored in a memory cache (memory level)
In general, Ceph does not send logs stored in memory to the output logs unless:
- A fatal signal is raised
- An assert in source code is triggered
- You request it
You can set different values for each of these subsystems. Ceph logging levels operate on scale of 1 to 20, where 1 is terse and 20 is verbose.
Use a single value for the log level and memory level to set them both to the same value. For example, debug_osd = 5 sets the debug level for the ceph-osd daemon to 5.
To use different values for the output log level and the memory level, separate the values with a forward slash (/). For example, debug_mon = 1/5 sets the debug log level for the ceph-mon daemon to 1 and its memory log level to 5.
The Most Used Ceph Subsystems and Their Default Values
| Subsystem | Log Level | Memory Level | Description |
|---|---|---|---|
|
| 1 | 5 | The administration socket |
|
| 1 | 5 | Authentication |
|
| 0 | 5 |
Any application or library that uses |
|
| 1 | 5 | The FileStore OSD back end |
|
| 1 | 5 | The OSD journal |
|
| 1 | 5 | The Metadata Servers |
|
| 0 | 5 | The Monitor client handles communication between most Ceph daemons and Monitors |
|
| 1 | 5 | Monitors |
|
| 0 | 5 | The messaging system between Ceph components |
|
| 0 | 5 | The OSD Daemons |
|
| 0 | 5 | The algorithm that Monitors use to establish a consensus |
|
| 0 | 5 | Reliable Autonomic Distributed Object Store, a core component of Ceph |
|
| 0 | 5 | The Ceph Block Devices |
|
| 1 | 5 | The Ceph Object Gateway |
Example Log Outputs
The following examples show the type of messages in the logs when you increase the verbosity for the Monitors and OSDs.
Monitor Debug Settings
debug_ms = 5 debug_mon = 20 debug_paxos = 20 debug_auth = 20
Example Log Output of Monitor Debug Settings
2016-02-12 12:37:04.278761 7f45a9afc700 10 mon.cephn2@0(leader).osd e322 e322: 2 osds: 2 up, 2 in 2016-02-12 12:37:04.278792 7f45a9afc700 10 mon.cephn2@0(leader).osd e322 min_last_epoch_clean 322 2016-02-12 12:37:04.278795 7f45a9afc700 10 mon.cephn2@0(leader).log v1010106 log 2016-02-12 12:37:04.278799 7f45a9afc700 10 mon.cephn2@0(leader).auth v2877 auth 2016-02-12 12:37:04.278811 7f45a9afc700 20 mon.cephn2@0(leader) e1 sync_trim_providers 2016-02-12 12:37:09.278914 7f45a9afc700 11 mon.cephn2@0(leader) e1 tick 2016-02-12 12:37:09.278949 7f45a9afc700 10 mon.cephn2@0(leader).pg v8126 v8126: 64 pgs: 64 active+clean; 60168 kB data, 172 MB used, 20285 MB / 20457 MB avail 2016-02-12 12:37:09.278975 7f45a9afc700 10 mon.cephn2@0(leader).paxosservice(pgmap 7511..8126) maybe_trim trim_to 7626 would only trim 115 < paxos_service_trim_min 250 2016-02-12 12:37:09.278982 7f45a9afc700 10 mon.cephn2@0(leader).osd e322 e322: 2 osds: 2 up, 2 in 2016-02-12 12:37:09.278989 7f45a9afc700 5 mon.cephn2@0(leader).paxos(paxos active c 1028850..1029466) is_readable = 1 - now=2016-02-12 12:37:09.278990 lease_expire=0.000000 has v0 lc 1029466 .... 2016-02-12 12:59:18.769963 7f45a92fb700 1 -- 192.168.0.112:6789/0 <== osd.1 192.168.0.114:6800/2801 5724 ==== pg_stats(0 pgs tid 3045 v 0) v1 ==== 124+0+0 (2380105412 0 0) 0x5d96300 con 0x4d5bf40 2016-02-12 12:59:18.770053 7f45a92fb700 1 -- 192.168.0.112:6789/0 --> 192.168.0.114:6800/2801 -- pg_stats_ack(0 pgs tid 3045) v1 -- ?+0 0x550ae00 con 0x4d5bf40 2016-02-12 12:59:32.916397 7f45a9afc700 0 mon.cephn2@0(leader).data_health(1) update_stats avail 53% total 1951 MB, used 780 MB, avail 1053 MB .... 2016-02-12 13:01:05.256263 7f45a92fb700 1 -- 192.168.0.112:6789/0 --> 192.168.0.113:6800/2410 -- mon_subscribe_ack(300s) v1 -- ?+0 0x4f283c0 con 0x4d5b440
OSD Debug Settings
debug_ms = 5 debug_osd = 20 debug_filestore = 20 debug_journal = 20
Example Log Output of OSD Debug Settings
2016-02-12 11:27:53.869151 7f5d55d84700 1 -- 192.168.17.3:0/2410 --> 192.168.17.4:6801/2801 -- osd_ping(ping e322 stamp 2016-02-12 11:27:53.869147) v2 -- ?+0 0x63baa00 con 0x578dee0 2016-02-12 11:27:53.869214 7f5d55d84700 1 -- 192.168.17.3:0/2410 --> 192.168.0.114:6801/2801 -- osd_ping(ping e322 stamp 2016-02-12 11:27:53.869147) v2 -- ?+0 0x638f200 con 0x578e040 2016-02-12 11:27:53.870215 7f5d6359f700 1 -- 192.168.17.3:0/2410 <== osd.1 192.168.0.114:6801/2801 109210 ==== osd_ping(ping_reply e322 stamp 2016-02-12 11:27:53.869147) v2 ==== 47+0+0 (261193640 0 0) 0x63c1a00 con 0x578e040 2016-02-12 11:27:53.870698 7f5d6359f700 1 -- 192.168.17.3:0/2410 <== osd.1 192.168.17.4:6801/2801 109210 ==== osd_ping(ping_reply e322 stamp 2016-02-12 11:27:53.869147) v2 ==== 47+0+0 (261193640 0 0) 0x6313200 con 0x578dee0 .... 2016-02-12 11:28:10.432313 7f5d6e71f700 5 osd.0 322 tick 2016-02-12 11:28:10.432375 7f5d6e71f700 20 osd.0 322 scrub_random_backoff lost coin flip, randomly backing off 2016-02-12 11:28:10.432381 7f5d6e71f700 10 osd.0 322 do_waiters -- start 2016-02-12 11:28:10.432383 7f5d6e71f700 10 osd.0 322 do_waiters -- finish
See Also
2.2. Configuring Logging at Runtime
To activate the Ceph debugging output, dout(), at runtime:
ceph tell <type>.<id> injectargs --debug-<subsystem> <value> [--<name> <value>]
Replace:
-
<type>with the type of Ceph daemons (osd,mon, ormds) -
<id>with a specific ID of the Ceph daemon. Alternatively, use*to apply the runtime setting to all daemons of a particular type. -
<subsystem>with a specific subsystem. See Section 2.1, “Ceph Subsystems” for details. -
<value>with a number from1to20, where1is terse and20is verbose
For example, to set the log level for the OSD subsystem on the OSD named osd.0 to 0 and the memory level to 5:
# ceph tell osd.0 injectargs --debug-osd 0/5
To see the configuration settings at runtime:
-
Log in to the host with a running Ceph daemon, for example
ceph-osdorceph-mon. Display the configuration:
ceph daemon <name> config show | less
Specify the name of the Ceph daemon, for example:
# ceph daemon osd.0 config show | less
See Also
- Section 2.3, “Configuring Logging in the Ceph Configuration File”
- The Logging Configuration Reference chapter in the Configuration Guide for Red Hat Ceph Storage 3
2.3. Configuring Logging in the Ceph Configuration File
To activate Ceph debugging output, dout() at boot time, add the debugging settings to the Ceph configuration file.
-
For subsystems common to each daemon, add the settings under the
[global]section. -
For subsystems for particular daemons, add the settings under a daemon section, such as
[mon],[osd], or[mds].
For example:
[global]
debug_ms = 1/5
[mon]
debug_mon = 20
debug_paxos = 1/5
debug_auth = 2
[osd]
debug_osd = 1/5
debug_filestore = 1/5
debug_journal = 1
debug_monc = 5/20
[mds]
debug_mds = 1See Also
- Section 2.1, “Ceph Subsystems”
- Section 2.2, “Configuring Logging at Runtime”
- The Logging Configuration Reference chapter in the Configuration Guide for Red Hat Ceph Storage 3
2.4. Accelerating Log Rotation
Increasing debugging level for Ceph components might generate a huge amount of data. If you have almost full disks, you can accelerate log rotation by modifying the Ceph log rotation file at /etc/logrotate.d/ceph. The Cron job scheduler uses this file to schedule log rotation.
Procedure: Accelerating Log Rotation
Add the size setting after the rotation frequency to the log rotation file:
rotate 7 weekly size <size> compress sharedscripts
For example, to rotate a log file when it reaches 500 MB:
rotate 7 weekly size 500 MB compress sharedscripts size 500M
Open the
crontabeditor:$ crontab -e
Add an entry to check the
/etc/logrotate.d/cephfile. For example, to instruct Cron to check/etc/logrotate.d/cephevery 30 minutes:30 * * * * /usr/sbin/logrotate /etc/logrotate.d/ceph >/dev/null 2>&1
See Also
- The Scheduling a Recurring Job Using Cron section in the System Administrator’s Guide for Red Hat Enterprise Linux 7.
