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:
COMPRESSAFTER
Number of days after which daily data files are to be
compressed. The compression program is given in the ZIP
variable.
HISTORY
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.
REPORTS
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.
SADC_OPTIONS
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.
YESTERDAY
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.
/etc/sysconfig/sysstat
Sebastien Godard (sysstat <at> orange.fr)
sadc(8), sa1(8), sa2(8)
http://pagesperso-orange.fr/sebastien.godard/
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 systat-AT-orange.fr. This
page was obtained from the project's upstream Git repository
⟨https://github.com/sysstat/sysstat.git⟩ on 2017-07-05. If you dis‐
cover 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 man-pages@man7.org
Linux APRIL 2015 SYSSTAT(5)
Pages that refer to this page: sadf(1), sar(1), sa1(8), sa2(8), sadc(8)