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- Rotate Log Files
Rotate Log Files¶
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Overview¶
When used with the --logpath
option or systemLog.path
setting, mongod
and mongos
instances
report a live account of all activity and operations to a log file.
When reporting activity data to a log file, by default, MongoDB only
rotates logs in response to the logRotate
command, or when
the mongod
or mongos
process receives a
SIGUSR1
signal from the operating system.
MongoDB’s standard log rotation approach archives the current
log file and starts a new one. To do this, the mongod
or
mongos
instance renames the current log file by appending
a UTC timestamp to the filename, in ISODate format. It then
opens a new log file, closes the old log file, and sends all new log
entries to the new log file.
You can also configure MongoDB to support the Linux/Unix logrotate
utility by setting systemLog.logRotate
or
--logRotate
to reopen
. With reopen
, mongod
or mongos
closes the log file, and
then reopens a log file with the same name, expecting that another
process renamed the file prior to rotation.
Finally, you can configure mongod
to send log data to the
syslog
using the --syslog
option. In
this case, you can take advantage of alternate log rotation tools.
See also
For information on logging, see the Process Logging section.
Default Log Rotation Behavior¶
By default, MongoDB uses the
--logRotate rename
behavior.
With rename
, mongod
or
mongos
renames the current log file by appending a UTC
timestamp to the filename, opens a new log file, closes the old log
file, and sends all new log entries to the new log file.
Start a mongod
instance.¶
You can also explicitly specify --logRotate rename
.
List the log files¶
In a separate terminal, list the matching files:
The results should include one log file, server1.log
.
View the new log files¶
List the new log files to view the newly-created log:
There should be two log files listed: server1.log
, which is the
log file that mongod
or mongos
made when it
reopened the log file, and server1.log.<timestamp>
, the renamed
original log file.
Rotating log files does not modify the “old” rotated log files. When
you rotate a log, you rename the server1.log
file to include
the timestamp, and a new, empty server1.log
file receives all
new log input.
Log Rotation with --logRotate reopen
¶
New in version 3.0.0.
Log rotation with --logRotate reopen
closes and opens
the log file following the typical Linux/Unix log rotate behavior.
Start a mongod
instance, specifying the reopen
--logRotate
behavior.¶
You must use the --logappend
option with
--logRotate reopen
.
List the log files¶
In a separate terminal, list the matching files:
The results should include one log file, server1.log
.
Syslog Log Rotation¶
With syslog log rotation, mongod
sends log data to the
syslog rather than writing it to a file.
Start a mongod
instance with the --syslog
option¶
Do not include --logpath
. Since --syslog
tells
mongod
to send log data to the syslog, specifying a
--logpath
will causes an error.
To specify the facility level used when logging messages to the syslog,
use the --syslogFacility
option or
systemLog.syslogFacility
configuration setting.
Rotate the log.¶
Store and rotate the log output using your systems default log rotation mechanism.