VNSTATD
Section: User Manuals (1)
Updated: APRIL 2009
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NAME
vnStat daemon - the alternative for cron based updating
SYNOPSIS
vnstatd
[
-Ddnpv?
] [
--daemon
] [
--nodaemon
] [
--debug
] [
--help
] [
--version
] [
--pidfile
file
] [
--config
file
]
DESCRIPTION
The purpose of
vnstatd
is to provide an alternative way for updating
vnstat(1)
databases. It 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. The
daemon 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 and exit if no databases can be found. The reason for this behaviour
is to avoid starting the daemon when it's clear that it wouldn't have
anything to do.
OPTIONS
- -d, --daemon
-
Fork process to background and run as a daemon.
- -n, --nodaemon
-
Stay in foreground attached to the current terminal and start update
process.
- -D, --debug
-
Provide additional output for debug purposes. The process will stay
attached to the terminal for output.
- -?, --help
-
Show a command summary.
- -v, --version
-
Show current version.
- -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.
- --config file
-
Use
file
as config file instead of using normal config file search function.
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.
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.
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.
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(1)
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(1),
signal(7)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- OPTIONS
-
- CONFIGURATION
-
- SIGNALS
-
- FILES
-
- RESTRICTIONS
-
- AUTHOR
-
- SEE ALSO
-
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