sadc(8) — Linux manual page


SADC(8)                      Linux User's Manual                     SADC(8)

NAME         top

       sadc - System activity data collector.

SYNOPSIS         top

       /usr/local/lib64/sa/sadc [ -C comment ] [ -D ] [ -F ] [ -f ] [ -L ] [
       -V ] [ -S { keyword[,...] | ALL | XALL } ] [ interval [ count ] ] [
       outfile ]

DESCRIPTION         top

       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

       Note: The sadc command only reports on local activities.

OPTIONS         top

       -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

       -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

              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.

ENVIRONMENT         top

       The sadc command takes into account the following environment

              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.

EXAMPLES         top

       /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.

BUGS         top

       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

FILES         top

              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.

AUTHOR         top

       Sebastien Godard (sysstat <at>

SEE ALSO         top

       sar(1), sa1(8), sa2(8), sadf(1), sysstat(5) 

COLOPHON         top

       This page is part of the sysstat (sysstat performance monitoring
       tools) project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug
       report for this manual page, send it to  This
       page was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-08-13.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-08-01.)  If you discover any rendering problems in
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Linux                             JULY 2020                          SADC(8)

Pages that refer to this page: sadf(1)sar(1)sysstat(5)sa1(8)sa2(8)