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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | ENVIRONMENT | EXAMPLES | BUGS | FILES | AUTHOR | SEE ALSO | COLOPHON |
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SADC(8) Linux User's Manual SADC(8)
sadc - System activity data collector.
/usr/local/lib64/sa/sadc [ -C comment ] [ -D ] [ -F ] [ -f ] [ -L
] [ -V ] [ -S { keyword[,...] | ALL | XALL } ] [ interval [ count
] ] [ outfile ]
The sadc command samples system data a specified number of times
(count) at a specified interval measured in seconds (interval).
It writes in binary format to the specified outfile or to standard
output. If outfile is set to -, then sadc uses the standard system
activity daily data file (see below). In this case, if the file
already exists, sadc will overwrite it if it is from a previous
month. By default sadc collects most of the data available from
the kernel. But there are also optional metrics, for which the
relevant options must be explicitly passed to sadc to be collected
(see option -S below).
The standard system activity daily data file is named saDD unless
option -D is used, in which case its name is saYYYYMMDD, where
YYYY stands for the current year, MM for the current month and DD
for the current day. By default it is located in the /var/log/sa
directory. Yet it is possible to specify an alternate location for
it: If outfile is a directory (instead of a plain file) then it
will be considered as the directory where the standard system
activity daily data file will be saved.
When the count parameter is not specified, sadc writes its data
endlessly. When both interval and count are not specified, and
option -C is not used, a dummy record, which is used at system
startup to mark the time when the counter restarts from 0, will be
written. For example, one of the system startup script may write
the restart mark to the daily data file by the command entry:
/usr/local/lib64/sa/sadc -
The sadc command is intended to be used as a backend to the sar
command.
Note: The sadc command only reports on local activities.
-C comment
When neither the interval nor the count parameters are
specified, this option tells sadc to write a dummy record
containing the specified comment string. This comment can
then be displayed with option -C of sar.
-D Use saYYYYMMDD instead of saDD as the standard system
activity daily data file name.
-F The creation of outfile will be forced. If the file already
exists and has a format unknown to sadc then it will be
truncated. This may be useful for daily data files created
by an older version of sadc and whose format is no longer
compatible with current one.
-f fdatasync() will be used to ensure data is written to disk.
This differs from the normal operation in that a sudden
system reset is less likely to result in the saDD datafiles
being corrupted. However, this is at the expense of
performance within the sadc process as forward progress
will be blocked while data is written to underlying disk
instead of just to cache.
-L sadc will try to get an exclusive lock on the outfile
before writing to it or truncating it. Failure to get the
lock is fatal, except in the case of trying to write a
normal (i.e. not a dummy and not a header) record to an
existing file, in which case sadc will try again at the
next interval. Usually, the only reason a lock would fail
would be if another sadc process were also writing to the
file. This can happen when cron is used to launch sadc. If
the system is under heavy load, an old sadc might still be
running when cron starts a new one. Without locking, this
situation can result in a corrupted system activity file.
-S { keyword[,...] | ALL | XALL }
Possible keywords are DISK, INT, IPV6, POWER, SNMP, XDISK,
ALL and XALL.
Specify which optional activities should be collected by
sadc. Some activities are optional to prevent data files
from growing too large. The DISK keyword indicates that
sadc should collect data for block devices. The INT keyword
indicates that sadc should collect data for system
interrupts. The IPV6 keyword indicates that IPv6 statistics
should be collected by sadc. The POWER keyword indicates
that sadc should collect power management statistics. The
SNMP keyword indicates that SNMP statistics should be
collected by sadc. The ALL keyword is equivalent to
specifying all the keywords above and therefore all
previous activities are collected.
The XDISK keyword is an extension to the DISK one and
indicates that partitions and filesystems statistics should
be collected by sadc in addition to disk statistics. This
option works only with kernels 2.6.25 and later. The XALL
keyword is equivalent to specifying all the keywords above
(including keyword extensions) and therefore all possible
activities are collected.
Important note: The activities (including optional ones)
saved in an existing data file prevail over those selected
with option -S. As a consequence, appending data to an
existing data file will result in option -S being ignored.
-V Print version number then exit.
The sadc command takes into account the following environment
variable:
S_TIME_DEF_TIME
If this variable exists and its value is UTC then sadc will
save its data in UTC time. sadc will also use UTC time
instead of local time to determine the current daily data
file located in the /var/log/sa directory.
/usr/local/lib64/sa/sadc 1 10 /tmp/datafile
Write 10 records of one second intervals to the
/tmp/datafile binary file.
/usr/local/lib64/sa/sadc -C "Backup Start" /tmp/datafile
Insert the comment "Backup Start" into the file
/tmp/datafile.
The /proc filesystem must be mounted for the sadc command to work.
All the statistics are not necessarily available, depending on the
kernel version used. sadc assumes that you are using at least a
2.6 kernel.
/var/log/sa/saDD
/var/log/sa/saYYYYMMDD
The standard system activity daily data files and their
default location. YYYY stands for the current year, MM for
the current month and DD for the current day.
/proc and /sys contain various files with system statistics.
Sebastien Godard (sysstat <at> orange.fr)
sar(1), sa1(8), sa2(8), sadf(1), sysstat(5)
https://github.com/sysstat/sysstat
https://sysstat.github.io/
This page is part of the sysstat (sysstat performance monitoring
tools) project. Information about the project can be found at
⟨http://sebastien.godard.pagesperso-orange.fr/⟩. If you have a bug
report for this manual page, send it to sysstat-AT-orange.fr.
This page was obtained from the project's upstream Git repository
⟨https://github.com/sysstat/sysstat.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-04.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
Linux AUGUST 2023 SADC(8)
Pages that refer to this page: sadf(1), sar(1), sysstat(5), sa1(8), sa2(8)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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