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)