Data Volume Monitor


We introduced a data volume monitor called vnstat in our develop image, see for more information about vnstat.


vnstat can be configured with the config file /etc/vnstat.conf

Our configuration sets wwan0 as default interface and runs the used database on a ramdisk (volatile). The responsible configuration values are the follows:

DatabaseDir "/run/vnstat"
Interface "wwan0"

The database is on path /run/vnstat/vnstat.db.


This volatile configuration gets lost at each reboot. If you want to persist the database then follow the guide in the next section.

The default configuration synchronizes the database every 5 minutes, so be aware that there is a latency in the displayed numbers.

Persisting Data base

The following lines show you about how you can persist the data volume over reboots:

  1. Stop the service: systemctl stop vnstat

  2. Adapt the configuration:

    • in /etc/vnstat.conf set the following setting: DatabaseDir “/var/lib/vnstat”

  3. Start the service: systemctl start vnstat

The service runs then on the database residing on the emmc. It will create a new database if no one is existing or continuing with the database residing in /var/lib/vnstat.

How To use

The help of vnstat is somehow self explaining and shows you how to use it:

vnstat --help

vnStat 2.6 by Teemu Toivola <tst at iki dot fi>

  -5,  --fiveminutes [limit]   show 5 minutes
  -h,  --hours [limit]         show hours
  -hg, --hoursgraph            show hours graph
  -d,  --days [limit]          show days
  -m,  --months [limit]        show months
  -y,  --years [limit]         show years
  -t,  --top [limit]           show top days

  -b, --begin <date>           set list begin date
  -e, --end <date>             set list end date

  --oneline [mode]             show simple parsable format
  --json [mode] [limit]        show database in json format
  --xml [mode] [limit]         show database in xml format

  -tr, --traffic [time]        calculate traffic
  -l,  --live [mode]           show transfer rate in real time
  -i,  --iface <interface>     select interface (default: wwan0)

Use "--longhelp" or "man vnstat" for complete list of options.

Example: show only the wwan0 data volume:

vnstat -i wwan0

Database updated: 2021-03-24 10:55:01

wwan0 since 2021-03-24

      rx:  84.78 KiB      tx:  84.83 KiB      total:  169.62 KiB

                 rx      |     tx      |    total    |   avg. rate
   2021-03     84.78 KiB |   84.83 KiB |  169.62 KiB |        0 bit/s
 estimated       --      |     --      |     --      |

                 rx      |     tx      |    total    |   avg. rate
     today     84.78 KiB |   84.83 KiB |  169.62 KiB |       35 bit/s
 estimated       186 KiB |     186 KiB |     371 KiB |