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 the standard output. If
outfile is set to -, then
sadc uses the standard system activity daily data file, the
/var/log/sa/sa dd file, where the dd parameter indicates the current day.
By default
sadc collects all the data available from the kernel.
Exceptions are interrupts and disks 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, 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/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
-d
Tell
sadc to report statistics for disks. By default
sadc does not report disks activity to prevent data files from growing too large.
-F
The creation of
outfile will be forced. If the file already exists and has not the format expected by
sadc then it will be truncated. This may be particularly useful for daily data files
created by an older version of sadc and whose format is no longer compatible
with current one.
-I
Tell
sadc to report statistics for all system interrupts. By default
sadc only reports statistics for the total number of interrupts.
-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.
-V
Print version number and usage then exit.
EXAMPLES
/usr/lib/sa/sadc 1 10 /tmp/datafile
Write 10 records of one second intervals to the /tmp/datafile binary file.
BUGS
/proc filesystem must be mounted for the
sadc command to work.
All the statistics are not necessarily available, depending on the kernel version used.
FILES
/var/log/sa/sa dd
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.
