lttng-enable-rotation - Man Page
Set an LTTng recording session rotation schedule
Synopsis
lttng [GENERAL OPTIONS] enable-rotation [--session=SESSION]
(--timer=PERIODUS | --size=SIZE | --timer=PERIODUS --size=SIZE)Description
The lttng enable-rotation command sets a recording session rotation schedule for:
With the --session=SESSION option
The recording session named SESSION.
Without the --session option
The current recording session (see lttng-concepts(7) to learn more about the current recording session).
See lttng-concepts(7) to learn more about the recording session rotation and trace chunk concepts.
With the --timer=PERIODUS option, the enable-rotation command sets a rotation schedule so that LTTng performs an automatic rotation at least every PERIODUS.
With the --size=SIZE option, the enable-rotation command sets a rotation schedule so that LTTng performs an automatic rotation every time the total size of the flushed part of the current trace chunk is at least SIZE.
For both the --timer and --size options, LTTng checks the schedule condition periodically using the monitor timers of the event record channels of the selected recording session (see the --monitor-timer option of the lttng-enable-channel(1) command). This means that:
With the --timer=PERIODUS option, LTTng can perform an automatic rotation when the elapsed time since the last automatic rotation is slightly greater than PERIODUS.
The exact precision depends on the precision of the monitor timer, which relies on the precision of the platform implementation of POSIX timers.
- With the --size=SIZE option, LTTng can perform an automatic rotation when the size of the flushed part of the current trace chunk is greater than SIZE.
You may combine the --timer and --size options.
See the lttng-concepts(7) to learn how LTTng names a trace chunk archive directory.
See the “Examples” section below for usage examples.
Unset a recording session rotation schedule with the lttng-disable-rotation(1) command.
Important
You may only use the enable-rotation command when all of the following conditions are true:
- The selected recording session was created in normal mode or in network streaming mode (see lttng-create(1)).
- No event record channel was created with a configured trace file count or size limit (see the --tracefile-size and --tracefile-count options of the lttng-enable-channel(1) command).
For a given recording session, LTTng only performs an automatic rotation when it’s not currently performing a rotation.
Options
See lttng(1) for GENERAL OPTIONS.
Rotation schedule condition
- --size=SIZE
Set a rotation schedule so that LTTng performs an automatic rotation 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.
- --timer=PERIODUS
Set a rotation schedule so that LTTng performs an automatic rotation approximately every PERIODUS microseconds.
The ms (milliseconds), s (seconds), m (minutes), and h (hours) suffixes are supported.
Recording target
- -s SESSION, --session=SESSION
Set a rotation schedule for the recording session named SESSION instead of the current recording session.
Program information
- -h, --help
Show help.
This option attempts to launch /usr/bin/man to view this manual page. Override the manual pager path with the LTTNG_MAN_BIN_PATH environment variable.
- --list-options
List available command options and quit.
Exit Status
- 0
Success
- 1
Command error
- 2
Undefined command
- 3
Fatal error
- 4
Command warning (something went wrong during the command)
Environment
- LTTNG_ABORT_ON_ERROR
Set to 1 to abort the process after the first error is encountered.
- LTTNG_HOME
Path to the LTTng home directory.
Defaults to $HOME.
Useful when the Unix user running the commands has a non-writable home directory.
- LTTNG_LIST_LEGACY
Set to 1 to use the legacy output format (LTTng 2.14 and earlier) for the lttng-list(1) command instead of the modern output format.
Note that the legacy output doesn’t show anything related to features introduced after LTTng 2.14.
- LTTNG_MAN_BIN_PATH
Absolute path to the manual pager to use to read the LTTng command-line help (with lttng-help(1) or with the --help option) instead of /usr/bin/man.
- LTTNG_NO_UTF_8
Set to 1 to NOT emit multi-byte UTF-8 sequences, even if the locale claims to support it.
- LTTNG_SESSION_CONFIG_XSD_PATH
Path to the directory containing the session.xsd recording session configuration XML schema.
- LTTNG_SESSIOND_PATH
Absolute path to the LTTng session daemon binary (see lttng-sessiond(8)) to spawn from the lttng-create(1) command.
The --sessiond-path general option overrides this environment variable.
- LTTNG_TERM_COLOR
Controls when to emit terminal SGR codes in the output.
The NO_COLOR environment variable overrides this.
One of:
- auto (default)
Only emit SGR codes when the standard output is connected to a color-capable terminal.
- always
Always emit SGR codes.
- never
Never emit SGR codes.
- NO_COLOR
If set and not empty, then it’s equivalent to setting LTTNG_TERM_COLOR to never.
See NO_COLOR <https://no-color.org/> to learn more.
Files
- $LTTNG_HOME/.lttngrc
Unix user’s LTTng runtime configuration.
This is where LTTng stores the name of the Unix user’s current recording session between executions of lttng(1). lttng-create(1) and lttng-set-session(1) set the current recording session.
- $LTTNG_HOME/lttng-traces
Default output directory of LTTng traces in local and snapshot modes.
Override this path with the --output option of the lttng-create(1) command.
- $LTTNG_HOME/.lttng
Unix user’s LTTng runtime and configuration directory.
- $LTTNG_HOME/.lttng/sessions
Default directory containing the Unix user’s saved recording session configurations (see lttng-save(1) and lttng-load(1)).
- /usr/local/etc/lttng/sessions
Directory containing the system-wide saved recording session configurations (see lttng-save(1) and lttng-load(1)).
Note
$LTTNG_HOME defaults to the value of the HOME environment variable.
Examples
Example 1. Set the size-based rotation schedule of the current recording session.
Example 2. Set the periodic rotation schedule of a specific recording session.
Resources
- LTTng project website <https://lttng.org>
- LTTng documentation <https://lttng.org/docs>
- LTTng bug tracker <https://bugs.lttng.org>
- Git repositories <https://git.lttng.org>
- GitHub organization <https://github.com/lttng>
- Continuous integration <https://ci.lttng.org/>
- Mailing list <https://lists.lttng.org/> for support and development: lttng-dev@lists.lttng.org
- IRC channel <irc://irc.oftc.net/lttng>: #lttng on irc.oftc.net
- Mastodon <https://mastodon.social/@lttng>
Copyright
This program is part of the LTTng-tools project.
LTTng-tools is distributed under the GNU General Public License version 2 <http://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html>. See the LICENSE <https://github.com/lttng/lttng-tools/blob/master/LICENSE> file for details.
Thanks
Special thanks to Michel Dagenais and the DORSAL laboratory <http://www.dorsal.polymtl.ca/> at École Polytechnique de Montréal for the LTTng journey.
Also thanks to the Ericsson teams working on tracing which helped us greatly with detailed bug reports and unusual test cases.
See Also
lttng(1), lttng-create(1), lttng-disable-rotation(1), lttng-rotate(1), lttng-concepts(7)
Referenced By
lttng(1), lttng-concepts(7), lttng-disable-rotation(1), lttng-rotate(1).