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.TH SADC 8 "JULY 2018" Linux "Linux User's Manual" -*- nroff -*-
.SH NAME
sadc \- System activity data collector.
.SH SYNOPSIS
.B /usr/lib64/sa/sadc [ -C
.I comment
.B ] [ -D ] [ -F ] [ -L ] [ -V ] [ -S { DISK | INT | IPV6 | POWER | SNMP | XDISK | ALL | XALL [,...] } ] [
.I interval
.B [
.I count
.B ] ] [
.I outfile
.B ]
.SH DESCRIPTION
The
.B sadc
command samples system data a specified number of times
(\fIcount\fR) at a specified interval measured in seconds
(\fIinterval\fR). It writes in binary format to the specified
.I outfile
or to standard output. If
.I outfile
is set to -, then
.B sadc
uses the standard system activity daily data file (see below).
In this case, if the file already exists,
.B sadc
will overwrite it if it is from a previous month.
By default
.B sadc
collects most of the data available from the kernel.
But there are also optional metrics, for which the
relevant options must be explicitly passed to
.B sadc
to be collected (see option -S below).
The standard system activity daily data file is named
.I saDD
unless option
.B -D
is used, in which case its name is
.IR 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
.I /var/log/sa
directory. Yet it is possible to specify an alternate location for
it: If
.I outfile
is a directory (instead of a plain file) then it will be considered
as the directory where the standard system activity daily data file
will be saved.
When the
.I count
parameter is not specified,
.B sadc
writes its data endlessly.
When both
.I interval
and
.I 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 example, one of the system startup script may write the restart mark to
the daily data file by the command entry:
.B "/usr/lib64/sa/sadc -"
The
.B sadc
command is intended to be used as a backend to the
.B sar
command.
Note: The
.B sadc
command only reports on local activities.
.SH OPTIONS
.IP "-C comment"
When neither the
.I interval
nor the
.I count
parameters are specified, this option tells
.B sadc
to write a dummy record containing the specified
.I comment
string.
This comment can then be displayed with option -C of
.BR sar .
.IP -D
Use
.I saYYYYMMDD
instead of
.I saDD
as the standard system activity daily data file name.
.IP -F
The creation of
.I outfile
will be forced. If the file already exists and has a format unknown to
.B sadc
then it will be truncated. This may be useful for daily data files
created by an older version of
.B sadc
and whose format is no longer compatible with current one.
.IP -L
.B sadc
will try to get an exclusive lock on the
.I outfile
before writing to it or truncating it. Failure to get the lock is fatal,
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
.B sadc
will try again at the next interval. Usually, the only reason a lock
would fail would be if another
.B sadc
process were also writing to the file. This can happen when cron is used
to launch
.BR sadc .
If the system is under heavy load, an old
.B sadc
might still be running when cron starts a new one. Without locking,
this situation can result in a corrupted system activity file.
.IP "-S { DISK | INT | IPV6 | POWER | SNMP | XDISK | ALL | XALL [,...] }"
Specify which optional activities should be collected by
.BR sadc .
Some activities are optional to prevent data files from growing too large.
The
.B DISK
keyword indicates that
.B sadc
should collect data for block devices.
The
.B INT
keyword indicates that
.B sadc
should collect data for system interrupts.
The
.B IPV6
keyword indicates that IPv6 statistics should be
collected by
.BR sadc .
The
.B POWER
keyword indicates that
.B sadc
should collect power management statistics.
The
.B SNMP
keyword indicates that SNMP statistics should be
collected by
.BR sadc .
The
.B ALL
keyword is equivalent to specifying all the keywords above and therefore
all previous activities are collected.
The
.B XDISK
keyword is an extension to the
.B DISK
one and indicates that partitions and filesystems statistics should be collected by
.B sadc
in addition to disk statistics. This option works only with kernels 2.6.25
and later.
The
.B 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.
.IP -V
Print version number then exit.
.SH ENVIRONMENT
The
.B sadc
command takes into account the following environment variable:
.IP S_TIME_DEF_TIME
If this variable exists and its value is
.BR UTC
then
.B sadc
will save its data in UTC time.
.B sadc
will also use UTC time instead of local time to determine the current
daily data file located in the
.IR /var/log/sa
directory.
.SH EXAMPLES
.B /usr/lib64/sa/sadc 1 10 /tmp/datafile
.RS
Write 10 records of one second intervals to the /tmp/datafile binary file.
.RE
.B /usr/lib64/sa/sadc -C Backup_Start /tmp/datafile
.RS
Insert the comment Backup_Start into the file /tmp/datafile.
.RE
.SH BUGS
The
.I /proc
filesystem must be mounted for the
.B sadc
command to work.
All the statistics are not necessarily available, depending on the kernel version used.
.B sadc
assumes that you are using at least a 2.6 kernel.
.SH FILES
.I /var/log/sa/saDD
.br
.I /var/log/sa/saYYYYMMDD
.RS
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.
.RE
.I /proc
and
.I /sys
contain various files with system statistics.
.SH AUTHOR
Sebastien Godard (sysstat <at> orange.fr)
.SH SEE ALSO
.BR sar (1),
.BR sa1 (8),
.BR sa2 (8),
.BR sadf (1),
.BR sysstat (5)
.I https://github.com/sysstat/sysstat
.I http://pagesperso-orange.fr/sebastien.godard/
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