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 channels of the selected recording session (see the --monitor-timer option of the lttng-enable-channel(1) command). This means that:

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:

  • The selected recording session was created in normal mode or in network streaming mode (see lttng-create(1)).
  • No 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_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_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.

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.

See the --size option.

$ lttng disable-rotation --size=256M

Example 2. Set the periodic rotation schedule of a specific recording session.

See the --timer and --session options.

$ lttng disable-rotation --session=my-session --timer=5m

Resources

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), lttng-stop(1).

14 June 2021 LTTng 2.13.7 LTTng Manual