vnStat FAQ (for version 1.4+, 15.4.2004)


1. How should dialup users use vnStat? There's some errors
because the interface isn't available when offline.

 That's all explained at the end of the README. The idea
 is to include vnStat with enable/disable parameters in
 scripts related with the used interface. Example scripts
 can be found from the pppd directory that came with the
 source package.

2. Does vnStat work for PPPOE users?

 Although I haven't tested it, it's been reported to work
 if the supplied ppp scripts are installed correctly. As
 always, see the README and the man page.

3. How do I uninstall vnStat?

 You only need to run 'make uninstall' in the directory that
 comes when the .tar.gz is extracted. Just make sure it's
 the same version you have installed.

4. What does the 'estimated' value mean?

 The estimated value is an calculated average that tries to
 guess the total traffic for the current day/month based on
 previous traffic. This estimate works fairly well if the
 monitored interface has constant traffic of the same
 magnitude (like game servers). It can't predic peaks but
 the accuracy usually gets better by the end of the day/month.

5. Why isn't the estimated value shown with --dumpdb?

 That features only dumps the database and since the estimate
 is always calculated in realtime, there's no reason to write
 it into the database.

6. How is the estimated value calculated?

 estimate = ( x / y ) * z

   x = traffic so far for the day/month
   y = passed minutes/hours ...
   z = total minutes/hours ...

7. Why does vnStat show sometimes multiple GB of traffic although
my network connection can't even transfer that much?
     OR
Each update adds the complete amount of traffic and 'vnstat -u -D'
claims that the system has been rebooted between updates.

 That's most likely a broken kernel. Run with --testkernel
 (version 1.2+ required) and see the result. See the next question
 for some explanation.

8. Why is there problems with most 2.4.18 kernels?

 Every current kernel has a btime (boot time) value in /proc/stat
 that indicates when the system was booted. vnStat uses this to
 know when the interface counters in the database should be
 reseted. Unfortunately, some kernels don't keep the btime value
 static even when the system isn't rebooted.

9. warning: integer constant is too large for "long" type -messages
during compiling with gcc 3.xx?

 Like that message says, that's only a warning, not an error.

10. About bug reports

 Any bug report should at least include an explanation about
 how the bug can be reproduced. Having output dumps usually
 helps and the --dumpdb feature should be used if there's some
 reason to assume the bug has something to do with the database.
 Also include information about the used distribution, kernel
 (uname -a), compiler (gcc --version) and network interface
 card. Read the report again before sending it. :)
