sysstat(5) — Linux manual page


SYSSTAT(5)                 Linux User's Manual                SYSSTAT(5)

NAME         top

       sysstat - sysstat configuration file.

DESCRIPTION         top

       This file is read by sa1(8) and sa2(8) shell scripts from the
       sysstat's set of tools.  It consists of a sequence of shell
       variable assignments used to configure sysstat logging.  The
       variables and their meanings are:

              Number of days after which daily data files are to be
              compressed.  The compression program is given in the ZIP

              Tell sa2 script to wait for a random delay in the
              indicated range before running.  This delay is expressed
              in seconds, and is aimed at preventing a massive I/O burst
              at the same time on VM sharing the same storage area.  A
              value of 0 means that sa2 script will generate its reports
              files immediately.

              The number of days during which a daily data file or a
              report should be kept. Data files or reports older than
              this number of days will be removed by the sa2(8) shell
              script.  Data files and reports are normally saved in the
              /var/log/sa directory, under the name saDD (for data
              files) or sarDD (for reports), where the DD parameter
              indicates the current day.

              The number of files actually kept in the /var/log/sa
              directory may be slightly higher than the HISTORY value
              due to the way the sa2 script figures out which files are
              to be removed (see below "How the sa2(8) script applies
              HISTORY value"). Using a value of 28 keeps a whole month's
              worth of data. If you set HISTORY to a value greater than
              28 then you should consider using sadc's option -D to
              prevent older data files from being overwritten (see
              sadc(8) manual page). In this latter case data files are
              named saYYYYMMDD and reports sarYYYYMMDD, where YYYY
              stands for the current year, MM for the current month and
              DD for the current day.

              How the sa2(8) script applies HISTORY value

              The sa2 script uses the find command with the -mtime
              option to figure out which files are to be removed. The
              find command interprets this value as "N 24 hour periods",
              ignoring any fractional part. This means that the last
              modified time of a given sa[r]DD data or report file,
              using a HISTORY of 1, has to have been modified at least
              two days ago before it will be removed. And for a HISTORY
              of 28 that would mean 29 days ago.

              To figure out how a HISTORY of 28 is applied in practice,
              we need to consider that the sa2 script that issues the
              find command to remove the old files typically runs just
              before midnight on a given system, and since the first
              record from sadc can also be written to the previous day's
              data file (thereby moving its modification time up a bit),
              the sa2 script will leave 30 files untouched. So for a
              setting of 28, and counting the data file of the current
              day, there will always be 31 files (or 30 files, depending
              on the number of days in a month) in the /var/log/sa
              directory during the majority of a given day.  E.g.:

              April 30th: 31 files (Apr 30th-1st, Mar 31th)
              May 1st: 30 files (May 1st, Apr 30th-2nd)

              Yet we can note the following exceptions (as inspected at
              Noon of the given day):

              February 28th: 31 files (Feb 28th-1st, Jan 31st, 30th &
              March 1st: 30 files (Mar 1st, Feb 28th-2nd, Jan 31st &
              March 2nd: 29 files (Mar 1st & 2nd, Feb 28th-3rd, Jan.
              March 3rd: 28 files (Mar 1st-3rd, Feb 28th-4th)
              March 4th - March 28th: 28 files
              March 29th: 29 files
              March 30th: 30 files
              March 31st: 31 files

              (Determining the number of files in March on a leap year
              is left as an exercise for the reader).

              Things are simpler if you use the sa[r]YYYYMMDD name
              format.  Apply the same logic as above in this case and
              you will find that there are always HISTORY + 3 files in
              the /var/log/sa directory during the majority of a given

              Maximum number of lines after which a header will be
              inserted in the report generated by sa2 script. By default
              there is only a header at the beginning of each report and
              it is not repeated afterwards.

              Set this variable to false to prevent the sa2 script from
              generating reports (the sarDD files).

       SA_DIR Directory where the standard system activity daily data
              and report files are saved. Its default value is

              Options that should be passed to sadc(8).  With these
              options (see sadc(8) manual page), you can select some
              additional data which are going to be saved in daily data
              files.  These options are used only when a new data file
              is created. They will be ignored with an already existing

              By default sa2 script generates yesterday's summary, since
              the cron job usually runs right after midnight. If you
              want sa2 to generate the summary of the same day (for
              example when cron job runs at 23:53) set this variable to

       ZIP    Program used to compress data and report files.

FILE         top


AUTHOR         top

       Sebastien Godard (sysstat <at>

SEE ALSO         top

       sadc(8), sa1(8), sa2(8) 

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 2022-12-17.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2022-12-16.)  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

Linux                          AUGUST 2022                    SYSSTAT(5)

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