sadc - System activity data collector.
/usr/lib/sysstat/sadc [ -C comment ] [ -D ] [ -F
] [ -f ] [ -L ] [ -V ] [ -S { keyword[,...] | 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 (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 explicitly passed to sadc to be
collected (see option -S below).
The standard system activity daily data file is named saDD
unless option -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 directory. 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 considered 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 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.
- -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 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 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 { 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 indicates that
IPv6 statistics should be collected by sadc. The POWER
keyword indicates that sadc should collect power management
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 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
/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.
Sebastien Godard (sysstat <at> orange.fr)
sar(1), sa1(8), sa2(8), sadf(1),
sysstat(5)
https://github.com/sysstat/sysstat
http://pagesperso-orange.fr/sebastien.godard/