All options are configured in the "[Journal]" section:
Controls where to store journal data. One of
"volatile", "persistent", "auto" and
"none". If "volatile", journal log data will be stored
only in memory, i.e. below the /run/log/journal hierarchy (which is created if
needed). If "persistent", data will be stored preferably on disk,
i.e. below the /var/log/journal hierarchy (which is created if needed), with a
fallback to /run/log/journal (which is created if needed), during early boot
and if the disk is not writable. "auto" is similar to
"persistent" but the directory /var/log/journal is not created if
needed, so that its existence controls where log data goes. "none"
turns off all storage, all log data received will be dropped. Forwarding to
other targets, such as the console, the kernel log buffer, or a syslog socket
will still work however. Defaults to "auto" in the default journal
namespace, and "persistent" in all others.
Can take a boolean value. If enabled (the default), data
objects that shall be stored in the journal and are larger than the default
threshold of 512 bytes are compressed before they are written to the file
system. It can also be set to a number of bytes to specify the compression
threshold directly. Suffixes like K, M, and G can be used to specify larger
Takes a boolean value. If enabled (the default), and a
sealing key is available (as created by journalctl(1)
command), Forward Secure Sealing (FSS) for all persistent
journal files is enabled. FSS is based on Seekable Sequential Key
 by G. A. Marson and B. Poettering
(doi:10.1007/978-3-642-40203-6_7) and may be used to protect journal files
from unnoticed alteration.
Controls whether to split up journal files per user,
either "uid" or "none". Split journal files are primarily
useful for access control: on UNIX/Linux access control is managed per file,
and the journal daemon will assign users read access to their journal files.
If "uid", all regular users (with UID outside the range of system
users, dynamic service users, and the nobody user) will each get their own
journal files, and system users will log to the system journal. See Users,
Groups, UIDs and GIDs on systemd systems for more details about UID
ranges. If "none", journal files are not split up by user and all
messages are instead stored in the single system journal. In this mode
unprivileged users generally do not have access to their own log data. Note
that splitting up journal files by user is only available for journals stored
persistently. If journals are stored on volatile storage (see Storage=
above), only a single journal file is used. Defaults to "uid".
Configures the rate limiting that is applied to all
messages generated on the system. If, in the time interval defined by
, more messages than specified in
are logged by a service, all further messages within
the interval are dropped until the interval is over. A message about the
number of dropped messages is generated. This rate limiting is applied
per-service, so that two services which log do not interfere with each other's
limits. Defaults to 10000 messages in 30s. The time specification for
may be specified in the following units:
"s", "min", "h", "ms", "us".
To turn off any kind of rate limiting, set either value to 0.
Note that the effective rate limit is multiplied with a factor
derived from the available free disk space for the journal. Currently, this
factor is calculated using the base 2 logarithm.
Table 1. Example RateLimitBurst= rate
modifications by the available disk space
|Available Disk Space
If a service provides rate limits for itself through
LogRateLimitIntervalSec= and/or LogRateLimitBurst= in
systemd.exec(5), those values will override the settings specified
SystemMaxFileSize=, SystemMaxFiles=, RuntimeMaxUse=,
Enforce size limits on the journal files stored. The
options prefixed with "System" apply to the journal files when
stored on a persistent file system, more specifically /var/log/journal. The
options prefixed with "Runtime" apply to the journal files when
stored on a volatile in-memory file system, more specifically
/run/log/journal. The former is used only when /var is mounted, writable, and
the directory /var/log/journal exists. Otherwise, only the latter applies.
Note that this means that during early boot and if the administrator disabled
persistent logging, only the latter options apply, while the former apply if
persistent logging is enabled and the system is fully booted up.
ignore all files with names not
ending with ".journal" or ".journal~", so only such files,
located in the appropriate directories, are taken into account when
calculating current disk usage.
SystemMaxUse= and RuntimeMaxUse= control how much
disk space the journal may use up at most. SystemKeepFree= and
RuntimeKeepFree= control how much disk space systemd-journald shall
leave free for other uses. systemd-journald will respect both limits
and use the smaller of the two values.
The first pair defaults to 10% and the second to 15% of the size
of the respective file system, but each value is capped to 4G. If the file
system is nearly full and either SystemKeepFree= or
RuntimeKeepFree= are violated when systemd-journald is started, the
limit will be raised to the percentage that is actually free. This means
that if there was enough free space before and journal files were created,
and subsequently something else causes the file system to fill up, journald
will stop using more space, but it will not be removing existing files to
reduce the footprint again, either. Also note that only archived files are
deleted to reduce the space occupied by journal files. This means that, in
effect, there might still be more space used than SystemMaxUse= or
RuntimeMaxUse= limit after a vacuuming operation is complete.
SystemMaxFileSize= and RuntimeMaxFileSize= control
how large individual journal files may grow at most. This influences the
granularity in which disk space is made available through rotation, i.e.
deletion of historic data. Defaults to one eighth of the values configured
with SystemMaxUse= and RuntimeMaxUse=, so that usually seven
rotated journal files are kept as history.
Specify values in bytes or use K, M, G, T, P, E as units for the
specified sizes (equal to 1024, 1024², ... bytes). Note that size
limits are enforced synchronously when journal files are extended, and no
explicit rotation step triggered by time is needed.
SystemMaxFiles= and RuntimeMaxFiles= control how
many individual journal files to keep at most. Note that only archived files
are deleted to reduce the number of files until this limit is reached;
active files will stay around. This means that, in effect, there might still
be more journal files around in total than this limit after a vacuuming
operation is complete. This setting defaults to 100.
The maximum time to store entries in a single journal
file before rotating to the next one. Normally, time-based rotation should not
be required as size-based rotation with options such as
SystemMaxFileSize= should be sufficient to ensure that journal files do
not grow without bounds. However, to ensure that not too much data is lost at
once when old journal files are deleted, it might make sense to change this
value from the default of one month. Set to 0 to turn off this feature. This
setting takes time values which may be suffixed with the units
"year", "month", "week", "day",
"h" or "m" to override the default time unit of
The maximum time to store journal entries. This controls
whether journal files containing entries older than the specified time span
are deleted. Normally, time-based deletion of old journal files should not be
required as size-based deletion with options such as SystemMaxUse=
should be sufficient to ensure that journal files do not grow without bounds.
However, to enforce data retention policies, it might make sense to change
this value from the default of 0 (which turns off this feature). This setting
also takes time values which may be suffixed with the units "year",
"month", "week", "day", "h" or "
m" to override the default time unit of seconds.
The timeout before synchronizing journal files to disk.
After syncing, journal files are placed in the OFFLINE state. Note that
syncing is unconditionally done immediately after a log message of priority
CRIT, ALERT or EMERG has been logged. This setting hence applies only to
messages of the levels ERR, WARNING, NOTICE, INFO, DEBUG. The default timeout
is 5 minutes.
Control whether log messages received by the journal
daemon shall be forwarded to a traditional syslog daemon, to the kernel log
buffer (kmsg), to the system console, or sent as wall messages to all
logged-in users. These options take boolean arguments. If forwarding to syslog
is enabled but nothing reads messages from the socket, forwarding to syslog
has no effect. By default, only forwarding to wall is enabled. These settings
may be overridden at boot time with the kernel command line options
"systemd.journald.forward_to_wall". If the option name is specified
without "=" and the following argument, true is assumed. Otherwise,
the argument is parsed as a boolean.
When forwarding to the console, the TTY to log to can be changed
with TTYPath=, described below.
When forwarding to the kernel log buffer (kmsg), make sure to
select a suitably large size for the log buffer, for example by adding
"log_buf_len=8M" to the kernel command line. systemd will
automatically disable kernel's rate-limiting applied to userspace processes
(equivalent to setting "printk.devkmsg=on").
MaxLevelKMsg=, MaxLevelConsole=, MaxLevelWall=
Controls the maximum log level of messages that are
stored in the journal, forwarded to syslog, kmsg, the console or wall (if that
is enabled, see above). As argument, takes one of "emerg",
"alert", "crit", "err", "warning",
"notice", "info", "debug", or integer values in
the range of 0–7 (corresponding to the same levels). Messages equal or
below the log level specified are stored/forwarded, messages above are
dropped. Defaults to "debug" for MaxLevelStore= and
MaxLevelSyslog=, to ensure that the all messages are stored in the
journal and forwarded to syslog. Defaults to "notice" for
MaxLevelKMsg=, "info" for MaxLevelConsole=, and
"emerg" for MaxLevelWall=. These settings may be overridden
at boot time with the kernel command line options
Takes a boolean value. If enabled systemd-journal
processes /dev/kmsg messages generated by the kernel. In the default journal
namespace this option is enabled by default, it is disabled in all
Change the console TTY to use if
ForwardToConsole=yes is used. Defaults to /dev/console.
The maximum line length to permit when converting stream
logs into record logs. When a systemd unit's standard output/error are
connected to the journal via a stream socket, the data read is split into
individual log records at newline ("\n", ASCII 10) and NUL
characters. If no such delimiter is read for the specified number of bytes a
hard log record boundary is artificially inserted, breaking up overly long
lines into multiple log records. Selecting overly large values increases the
possible memory usage of the Journal daemon for each stream client, as in the
worst case the journal daemon needs to buffer the specified number of bytes in
memory before it can flush a new log record to disk. Also note that permitting
overly large line maximum line lengths affects compatibility with traditional
log protocols as log records might not fit anymore into a single
AF_UNIX or AF_INET datagram. Takes a size in bytes. If the value
is suffixed with K, M, G or T, the specified size is parsed as Kilobytes,
Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively.
Defaults to 48K, which is relatively large but still small enough so that log
records likely fit into network datagrams along with extra room for metadata.
Note that values below 79 are not accepted and will be bumped to 79.