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

              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 /var/log/sa.

              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 one.

              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 no.

       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 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
       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                             JULY 2020                       SYSSTAT(5)

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