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SADC(8) Linux User's Manual SADC(8)
NAME
sadc - System activity data collector.
SYNOPSIS
/usr/lib64/sa/sadc [ -C comment ] [ -F ] [ -L ] [ -V ] [ -f ] [ -S { INT | DISK | SNMP |
IPV6 | POWER | XDISK | 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 out-
file or to standard output. If outfile is set to -, then sadc uses the standard system
activity daily data file, the /var/log/sa/sadd file, where the dd parameter indicates the
current day. In this case, sadc will overwrite the file if it is from a previous month.
By default sadc collects all the data available from the kernel. Exceptions are inter-
rupts and disk data, for which the relevant options must be explicitly passed to sadc (see
options below).
When the count parameter is not specified, sadc writes its data endlessly. 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 example, one of the system startup script may write the restart mark to the daily data
file by the command entry:
/usr/lib64/sa/sadc -
The sadc command is intended to be used as a backend to the sar command.
Note: The sadc command only reports on local activities.
OPTIONS
-C comment
When neither the interval nor the count parameters are specified, 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.
-F The creation of outfile will be forced. If the file already exists and has a format
unknown to sadc then it will be truncated. This may be useful for daily data files
created by an older version of sadc and whose format is no longer compatible with
current 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 written 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 trun-
cating 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 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 locking, this situ-
ation can result in a corrupted system activity file.
-S { INT | DISK | SNMP | IPV6 | POWER | XDISK | ALL | XALL }
Specify which optional activities should be collected by sadc. Some activities are
optional to prevent data files from growing too large. The INT keyword indicates
that sadc should collect data for system interrupts. The DISK keyword indicates
that sadc should collect data for block devices. The SNMP and IPV6 keywords indi-
cate respectively that SNMP and IPv6 statistics should be collected by sadc. The
POWER keyword indicates that sadc should collect power management statistics. The
ALL keyword is equivalent to specifying all the keywords above and therefore all
previous activities 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 equiva-
lent to specifying all the keywords above (including keyword extensions) and there-
fore 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/sa directory.
EXAMPLES
/usr/lib64/sa/sadc 1 10 /tmp/datafile
Write 10 records of one second intervals to the /tmp/datafile binary file.
/usr/lib64/sa/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 kernel version used.
sadc assumes that you are using at least a 2.6 kernel.
FILES
/var/log/sa/sadd
Indicate the daily data file, where the dd parameter is a number representing the
day of the month.
/proc contains various files with system statistics.
AUTHOR
Sebastien Godard (sysstat <at> orange.fr)
SEE ALSO
sar(1), sa1(8), sa2(8), sadf(1), sysstat(5)
http://pagesperso-orange.fr/sebastien.godard/
Linux JUNE 2013 SADC(8)
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