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

       sysstat - sysstat configuration file.

       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 variable.

              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/sysstat  direc‐
              tory,  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/sysstat 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 modifica‐
              tion 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/sysstat
              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).

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

              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.

       ZIP    Program used to compress data and report files.


       Sebastien Godard (sysstat <at> orange.fr)

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


Linux                                       JUNE 2014                                  SYSSTAT(5)

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