Provided by: vnstat_1.11-2_amd64 
NAME
vnStatd - the alternative for cron based updating
SYNOPSIS
vnstatd [ -Ddnpsv? ] [ --config file ] [ --daemon ] [ --debug ] [ --help ] [ --noadd ] [
--nodaemon ] [ --pidfile file ] [ --sync ] [ --version ]
DESCRIPTION
The purpose of vnstatd is to provide a more flexible way for updating vnstat(1) databases
than what using cron for updating can provide. The daemon makes possible updating
databases more often but at the same time requires less disk access since data can be
cached and written only later to disk at a user configurable interval. It is also able to
track how interfaces come and go without the need of additional scripts that are required
with cron based updates.
vnstatd is the command for starting the daemon. The daemon can either fork itself to run
as a background process or stay attached to the terminal. It supports logging to a user
selectable file or using syslog.
Once started, the daemon will check if there are any databases available in the database
directory that has been specified in the configuration file. New databases will be created
for all available interfaces excluding pseudo interfaces lo, lo0 and sit0 if no databases
are found during startup.
OPTIONS
--config file
Use file as config file instead of using normal config file search function.
-d, --daemon
Fork process to background and run as a daemon.
-D, --debug
Provide additional output for debug purposes. The process will stay attached to the
terminal for output.
--noadd
Disable automatic creation of new databases for all available interfaces if the
daemon is started with zero database found. Pseudo interfaces lo, lo0 and sit0 are
excluded from getting added.
-n, --nodaemon
Stay in foreground attached to the current terminal and start update process.
-p, --pidfile file
Write the process id to file and use it for locking so that another instance of the
daemon cannot be started if the same file is specified.
-s, --sync
Synchronize internal counters in the database with interface counters for all
available interfaces before starting traffic monitoring. Use this option if the
traffic between the previous shutdown and the current startup of the daemon needs
to be ignored. This option isn't required in normal use because the daemon will
automatically synchronize the internal counters after a system reboot, if enought
time has passed since the daemon was previously running or if the internal counters
are clearly out of sync.
-v, --version
Show current version.
-?, --help
Show a command summary.
CONFIGURATION
The behaviour of the daemon is configured mainly using the configuration keywords
UpdateInterval, PollInterval and SaveInterval in the configuration file.
UpdateInterval defines in seconds how often the interface data is updated. This is
similar to the run interval for alternative cron based updating. However, the difference
is that the data doesn't get written to disk during updates.
PollInterval defines in seconds how often the list of available interfaces is checked for
possible changes. The minimum value is 2 seconds and the maximum 60 seconds. PollInterval
also defines the resolution for other intervals.
SaveInterval defines in minutes how often cached interface data is written to disk. A
write can only occur during the updating of interface data. Therefore, the value should be
a multiple of UpdateInterval with a maximum value of 60 minutes.
The default values of UpdateInterval 20, SaveInterval 5 and PollInterval 2 are usually
suitable for most systems and provide a similar behaviour as cron based updating does but
with a better resolution for interface changes and fast interfaces.
For embedded and/or low power systems more tuned configurations are possible. In such
cases if the interfaces are mostly static the PollInterval can be rised to around 10-30
seconds and UpdateInterval set to 60 seconds. Higher values up to 300 seconds are possible
if the interface speed is 10 Mbit or less. SaveInterval can be rised for example to 15,
30 or even 60 minutes depending on how often the data needs to be viewed.
SIGNALS
The daemon is listening to signals SIGHUP, SIGINT and SIGTERM. Sending the SIGHUP signal
to the daemon will cause cached data to be written to disk, a rescan of the database
directory and a reload of settings from the configuration file. However, the pid file will
not be updated even if it's configuration setting has been changed.
SIGTERM and SIGINT signals will cause the daemon to write all cached data to disk and then
exit.
FILES
/var/lib/vnstat/
Default database directory. Files are named according to the monitored interfaces.
/etc/vnstat.conf
Config file that will be used unless $HOME/.vnstatrc exists. See the configuration
chapter and vnstat.conf(5) for more information.
/var/log/vnstat.log
Log file that will be used if logging to file is enable and no other file is
specified in the config file.
/var/run/vnstat.pid
File used for storing the process id if no other file is specified in the
configuration file or using the command line parameter.
RESTRICTIONS
Updates needs to be executed at least as often as it is possible for the interface to
generate enough traffic to wrap the kernel interface traffic counter. Otherwise it is
possible that some traffic won't be seen. This isn't an issue for 64 bit kernels but at
least one update every hour is always required in order to provide proper input. With 32
bit kernels the maximum time between two updates depends on how fast the interface can
transfer 4 GiB. Calculated theoretical times are:
10 Mbit: 54 minutes
100 Mbit: 5 minutes
1000 Mbit: 30 seconds
However, for 1000 Mbit interfaces updating once every minute is usually a working
solution.
Virtual and aliased interfaces cannot be monitored because the kernel doesn't provide
traffic information for that type of interfaces. Such interfaces are usually named eth0:0,
eth0:1, eth0:2 etc. where eth0 is the actual interface being aliased.
AUTHOR
Teemu Toivola <tst at iki dot fi>
SEE ALSO
vnstat(1), vnstati(1), vnstat.conf(5), signal(7)