SADC(8) Linux User's Manual SADC(8)
NAME
sadc - System activity data collector.
SYNOPSIS
/usr/lib/sysstat/sadc [ -C comment ] [ -D ] [ -F ] [ -f ] [ -L ] [ -V ]
[ -S { keyword[,...] | ALL | XALL } ] [ interval [ count ] ] [ outfile
]
DESCRIPTION
The sadc command samples system data a specified number of times
(count) at a specified interval measured in seconds (interval). It
writes in binary format to the specified outfile or to standard output.
If outfile is set to -, then sadc uses the standard system activity
daily data file (see below). In this case, if the file already exists,
sadc will overwrite it if it is from a previous month. By default sadc
collects most of the data available from the kernel. But there are
also optional metrics, for which the relevant options must be explic-
itly passed to sadc to be collected (see option -S below).
The standard system activity daily data file is named saDD unless op-
tion -D is used, in which case its name is saYYYYMMDD, where YYYY
stands for the current year, MM for the current month and DD for the
current day. By default it is located in the /var/log/sysstat direc-
tory. Yet it is possible to specify an alternate location for it: If
outfile is a directory (instead of a plain file) then it will be con-
sidered as the directory where the standard system activity daily data
file will be saved.
When the count parameter is not specified, sadc writes its data end-
lessly. When both interval and count are not specified, and option -C
is not used, a dummy record, which is used at system startup to mark
the time when the counter restarts from 0, will be written. For exam-
ple, one of the system startup script may write the restart mark to the
daily data file by the command entry:
/usr/lib/sysstat/sadc -
The sadc command is intended to be used as a backend to the sar com-
mand.
Note: The sadc command only reports on local activities.
OPTIONS
-C comment
When neither the interval nor the count parameters are speci-
fied, this option tells sadc to write a dummy record containing
the specified comment string. This comment can then be displayed
with option -C of sar.
-D Use saYYYYMMDD instead of saDD as the standard system activity
daily data file name.
-F The creation of outfile will be forced. If the file already ex-
ists and has a format unknown to sadc then it will be truncated.
This may be useful for daily data files created by an older ver-
sion of sadc and whose format is no longer compatible with cur-
rent one.
-f fdatasync() will be used to ensure data is written to disk. This
differs from the normal operation in that a sudden system reset
is less likely to result in the saDD datafiles being corrupted.
However, this is at the expense of performance within the sadc
process as forward progress will be blocked while data is writ-
ten to underlying disk instead of just to cache.
-L sadc will try to get an exclusive lock on the outfile before
writing to it or truncating it. Failure to get the lock is fa-
tal, except in the case of trying to write a normal (i.e. not a
dummy and not a header) record to an existing file, in which
case sadc will try again at the next interval. Usually, the only
reason a lock would fail would be if another sadc process were
also writing to the file. This can happen when cron is used to
launch sadc. If the system is under heavy load, an old sadc
might still be running when cron starts a new one. Without lock-
ing, this situation can result in a corrupted system activity
file.
-S { keyword[,...] | ALL | XALL }
Possible keywords are DISK, INT, IPV6, POWER, SNMP, XDISK, ALL
and XALL.
Specify which optional activities should be collected by sadc.
Some activities are optional to prevent data files from growing
too large. The DISK keyword indicates that sadc should collect
data for block devices. The INT keyword indicates that sadc
should collect data for system interrupts. The IPV6 keyword in-
dicates that IPv6 statistics should be collected by sadc. The
POWER keyword indicates that sadc should collect power manage-
ment statistics. The SNMP keyword indicates that SNMP statistics
should be collected by sadc. The ALL keyword is equivalent to
specifying all the keywords above and therefore all previous ac-
tivities are collected.
The XDISK keyword is an extension to the DISK one and indicates
that partitions and filesystems statistics should be collected
by sadc in addition to disk statistics. This option works only
with kernels 2.6.25 and later. The XALL keyword is equivalent to
specifying all the keywords above (including keyword extensions)
and therefore all possible activities are collected.
Important note: The activities (including optional ones) saved
in an existing data file prevail over those selected with option
-S. As a consequence, appending data to an existing data file
will result in option -S being ignored.
-V Print version number then exit.
ENVIRONMENT
The sadc command takes into account the following environment variable:
S_TIME_DEF_TIME
If this variable exists and its value is UTC then sadc will save
its data in UTC time. sadc will also use UTC time instead of
local time to determine the current daily data file located in
the /var/log/sysstat directory.
EXAMPLES
/usr/lib/sysstat/sadc 1 10 /tmp/datafile
Write 10 records of one second intervals to the /tmp/datafile
binary file.
/usr/lib/sysstat/sadc -C "Backup Start" /tmp/datafile
Insert the comment "Backup Start" into the file /tmp/datafile.
BUGS
The /proc filesystem must be mounted for the sadc command to work.
All the statistics are not necessarily available, depending on the ker-
nel version used. sadc assumes that you are using at least a 2.6 ker-
nel.
FILES
/var/log/sysstat/saDD
/var/log/sysstat/saYYYYMMDD
The standard system activity daily data files and their default
location. YYYY stands for the current year, MM for the current
month and DD for the current day.
/proc and /sys contain various files with system statistics.
AUTHOR
Sebastien Godard (sysstat <at> orange.fr)
SEE ALSO
sar(1), sa1(8), sa2(8), sadf(1), sysstat(5)
https://github.com/sysstat/sysstat
http://pagesperso-orange.fr/sebastien.godard/
Linux JULY 2020 SADC(8)
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