VNSTATD(1) User Manuals VNSTATD(1)NAMEvnstatd - daemon based database updating for vnStat
SYNOPSISvnstatd [ -Ddnpsv? ] [ --config file ] [ --daemon ] [ --debug ] [ -g
group ] [ --group group ] [ --help ] [ --noadd ] [ --nodaemon ] [
--pidfile file ] [ --sync ] [ --u user ] [ --user user ] [ --version ]
DESCRIPTION
The purpose of vnstatd is to provide a more flexible and robust way for
updating vnstat(1) databases than what using cron for updating can pro‐
vide. The daemon makes possible updating databases more often but at
the same time causes less disk access since data can be cached and
written only later to disk at a user configurable interval. The avail‐
ability of each interface is automatically tracked which removes the
need for additional scripts to be implemented and called when an inter‐
face comes online or goes offline.
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 ter‐
minal. It supports logging to a user selectable file or using syslog.
Once started, the daemon will read vnstat.conf(5) if available and then
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. This behaviour
can be disabled if needed. The daemon will then proceed to track the
availability of monitored interfaces, process the interface traffic
statistics and write new values to databases at a configured interval.
As a result, the daemon ends up spending most of the time sleeping
between updates.
OPTIONS--config file
Use file as configuration file instead of using normal configu‐
ration file search functionality.
-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.
-g, --group group
Set daemon process group to group during startup. group can be
either the name of the group or a numerical group id. This
option can only be used when the process is started as root.
--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
the 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 dae‐
mon was previously running or if the internal counters are
clearly out of sync.
-u, --user user
Set daemon process user to user during startup. user can be
either the login of the user or a numerical user id. This option
can only be used when the process is started as root.
-v, --version
Show current version of the daemon executable.
-?, --help
Show a command option summary.
CONFIGURATION
The behaviour of the daemon is configured mainly using the configura‐
tion keywords UpdateInterval, PollInterval and SaveInterval in the con‐
figuration file.
UpdateInterval defines in seconds how often the interface data is
fetched and updated. This is similar to the run interval for alterna‐
tive cron based updating. However, the difference is that the data
doesn't directly get written to disk during updates.
PollInterval defines in seconds how often the list of available inter‐
faces 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 inter‐
face data. Therefore, the value should be a multiple of UpdateInterval
with a maximum value of 60 minutes.
The default values of UpdateInterval 30, SaveInterval 5 and PollInter‐
val 5 are usually suitable for most systems and provide a similar be‐
haviour 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 increased to around 10-30 seconds and UpdateInter‐
val set to 60 seconds. Higher values up to 300 seconds are possible if
the interface speed is 10 Mbit or less. SaveInterval can be increased
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 location will not be
changed even if it's configuration setting has been modified.
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 informa‐
tion.
/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 speci‐
fied in the configuration file or using the command line parame‐
ter.
RESTRICTIONS
Updates needs to be executed at least as often as it is possible for
the interface to generate enough traffic to overflow the kernel inter‐
face 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 usable solution if faster updates can't be used.
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 ALSOvnstat(1), vnstati(1), vnstat.conf(5), signal(7)version 1.14 APRIL 2015 VNSTATD(1)
