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sadc

System activity data collector.

/usr/lib/sysstat/sadc [ -C comment ] [ -F ] [ -L ] [ -V ] [ -S { INT | DISK | SNMP | IPV6 | POWER | XDISK | ALL | XALL } ] [ interval [ count ] ] [ outfile ]

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, the /var/log/sysstat/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 most of the data available from the kernel. But there are also optional metrics, for which the relevant options must be explicitly passed to sadc to be collected (see option -S 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/lib/sysstat/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.

-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.

-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 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 situation 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 indicate 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 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.

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.

/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.

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.

/var/log/sysstat/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.

Sebastien Godard (sysstat <at> orange.fr)

sar(1), sa1(8), sa2(8), sadf(1), sysstat(5)

http://pagesperso-orange.fr/sebastien.godard/

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