1SYSSTAT(5) Linux User's Manual SYSSTAT(5)
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6 sysstat - sysstat configuration file.
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10 This file is read by sa1(8) and sa2(8) shell scripts from the sysstat's
11 set of tools. It consists of a sequence of shell variable assignments
12 used to configure sysstat logging. The variables and their meanings
13 are:
14 COMPRESSAFTER
16 Number of days after which daily data files are to be com‐
17 pressed. The compression program is given in the ZIP variable.
18 DELAY_RANGE
20 Tell sa2 script to wait for a random delay in the indicated
21 range before running. This delay is expressed in seconds, and
22 is aimed at preventing a massive I/O burst at the same time on
23 VM sharing the same storage area. A value of 0 means that sa2
24 script will generate its reports files immediately.
25 HISTORY
27 The number of days during which a daily data file or a report
28 should be kept. Data files or reports older than this number of
29 days will be removed by the sa2(8) shell script. Data files and
30 reports are normally saved in the /var/log/sa directory, under
31 the name saDD (for data files) or sarDD (for reports), where the
32 DD parameter indicates the current day.
33 The number of files actually kept in the /var/log/sa directory
35 may be slightly higher than the HISTORY value due to the way the
36 sa2 script figures out which files are to be removed (see below
37 "How the sa2(8) script applies HISTORY value"). Using a value of
38 28 keeps a whole month's worth of data. If you set HISTORY to a
39 value greater than 28 then you should consider using sadc's op‐
40 tion -D to prevent older data files from being overwritten (see
41 sadc(8) manual page). In this latter case data files are named
42 saYYYYMMDD and reports sarYYYYMMDD, where YYYY stands for the
43 current year, MM for the current month and DD for the current
44 day.
45 How the sa2(8) script applies HISTORY value
47 The sa2 script uses the find command with the -mtime option to
49 figure out which files are to be removed. The find command in‐
50 terprets this value as "N 24 hour periods", ignoring any frac‐
51 tional part. This means that the last modified time of a given
52 sa[r]DD data or report file, using a HISTORY of 1, has to have
53 been modified at least two days ago before it will be removed.
54 And for a HISTORY of 28 that would mean 29 days ago.
55 To figure out how a HISTORY of 28 is applied in practice, we
57 need to consider that the sa2 script that issues the find com‐
58 mand to remove the old files typically runs just before mid-
59 night on a given system, and since the first record from sadc
60 can also be written to the previous day's data file (thereby
61 moving its modification time up a bit), the sa2 script will
62 leave 30 files untouched. So for a setting of 28, and counting
63 the data file of the current day, there will always be 31 files
64 (or 30 files, depending on the number of days in a month) in the
65 /var/log/sa directory during the majority of a given day. E.g.:
66 April 30th: 31 files (Apr 30th-1st, Mar 31th)
68 May 1st: 30 files (May 1st, Apr 30th-2nd)
69 Yet we can note the following exceptions (as inspected at Noon
71 of the given day):
72 February 28th: 31 files (Feb 28th-1st, Jan 31st, 30th & 29th)
74 March 1st: 30 files (Mar 1st, Feb 28th-2nd, Jan 31st & 30th)
75 March 2nd: 29 files (Mar 1st & 2nd, Feb 28th-3rd, Jan. 31st)
76 March 3rd: 28 files (Mar 1st-3rd, Feb 28th-4th)
77 March 4th - March 28th: 28 files
78 March 29th: 29 files
79 March 30th: 30 files
80 March 31st: 31 files
81 (Determining the number of files in March on a leap year is left
83 as an exercise for the reader).
84 Things are simpler if you use the sa[r]YYYYMMDD name format.
86 Apply the same logic as above in this case and you will find
87 that there are always HISTORY + 3 files in the /var/log/sa di‐
88 rectory during the majority of a given day.
89 REPORTS
91 Set this variable to false to prevent the sa2 script from gener‐
92 ating reports (the sarDD files).
93 SA_DIR Directory where the standard system activity daily data and re‐
95 port files are saved. Its default value is /var/log/sa.
96 SADC_OPTIONS
98 Options that should be passed to sadc(8). With these options
99 (see sadc(8) manual page), you can select some additional data
100 which are going to be saved in daily data files. These options
101 are used only when a new data file is created. They will be ig‐
102 nored with an already existing one.
103 YESTERDAY
105 By default sa2 script generates yesterday's summary, since the
106 cron job usually runs right after midnight. If you want sa2 to
107 generate the summary of the same day (for example when cron job
108 runs at 23:53) set this variable to no.
109 ZIP Program used to compress data and report files.
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114 /etc/sysconfig/sysstat
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118 Sebastien Godard (sysstat <at> orange.fr)
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122 sadc(8), sa1(8), sa2(8)
123 https://github.com/sysstat/sysstat
125 http://pagesperso-orange.fr/sebastien.godard/
126Linux JULY 2020 SYSSTAT(5)