Document tracing session rotation features

[lttng-tools.git] / doc / man / lttng-enable-rotation.1.txt

lttng-enable-rotation(1)
========================


NAME
----
lttng-enable-rotation - Set a tracing session's automatic rotation schedule


SYNOPSIS
--------
[verse]
*lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *enable-rotation* (option:--timer='PERIOD' | option:--size='SIZE')
      [option:--session='SESSION']


DESCRIPTION
-----------
The `lttng enable-rotation` command sets an automatic rotation schedule
for the current tracing session, or for the tracing session named
'SESSION' if provided. See man:lttng-rotate(1) for more information
about the concepts of a tracing session _rotation_ and a _trace chunk_.

With the option:--timer option, the rotation schedule is set so that an
automatic rotation occurs at least every 'PERIOD' (microseconds without
a unit suffix).

With the option:--size option, the rotation schedule is set
so that an automatic rotation occurs every time the total size of the
flushed part of the current trace chunk is at least 'SIZE' (bytes
without a unit suffix).

With both the option:--timer and option:--size options, LTTng checks the
schedule condition periodically using the monitor timers of the tracing
session's channels. This means that, with the option:--timer option, the
automatic rotation can occur when the elapsed time since the last
automatic rotation is greater than 'PERIOD', and with the option:--size
option, the automatic rotation can occur when the size of the flushed
part of the current trace chunk is greater than 'SIZE'. See the
nloption:--monitor-timer option in man:lttng-enable-channel(1) for more
information about the monitor timer.

The naming convention of a trace chunk archive which an automatic
rotation creates is the same as with the manual rotation command,
man:lttng-rotate(1).

For a given tracing session, you cannot set multiple automatic rotation
schedules with the option:--timer or the option:--size option.

You can unset an automatic rotation schedule with the
man:lttng-disable-rotation(1) command.

See <<limitations,LIMITATIONS>> for important limitations regarding
this command.


include::common-cmd-options-head.txt[]


Automatic rotation schedule condition
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
One of:

option:--size='SIZE'::
    Set an automatic rotation schedule so that an automatic rotation
    occurs every time the total size of the flushed part of the current
    trace chunk is at least 'SIZE' bytes. The `k` (kiB), `M` (MiB), and
    `G` (GiB) suffixes are supported.

option:--timer='PERIOD'::
    Set an automatic rotation schedule so that an automatic rotation
    occurs at least every 'PERIOD' microseconds. The
    `ms` (milliseconds), `s` (seconds), `m` (minutes), and `h` (hours)
    suffixes are supported.


Target
~~~~~~
option:-s 'SESSION', option:--session='SESSION'::
    Set an automatic rotation schedule for the tracing session named
    'SESSION' instead of the current tracing session.


include::common-cmd-help-options.txt[]


[[limitations]]
LIMITATIONS
-----------
The `lttng enable-rotation` command only works when:

* The tracing session is created in normal mode or in network streaming
  mode (see man:lttng-create(1)).

* No channel was created with a configured trace file count or size
  limit (see the nloption:--tracefile-size and
  nloption:--tracefile-count options in man:lttng-enable-channel(1)).

For a given tracing session, LTTng only performs an automatic rotation
when no other rotation is currently happening.


include::common-cmd-footer.txt[]


SEE ALSO
--------
man:lttng-rotate(1),
man:lttng-disable-rotation(1),
man:lttng(1)