vnstat not updating on certain interfaces

Question

vnstat is updating only one interface every five minutes. I have to use vnstat -u to manually update the rest of interfaces. All interfaces are already enabled, but only one interface is updating every 5 minutes.

Answer 1

Check which user the vnstat daemon is running as using ps aux | grep [v]nstat.

I recently had the same problem and after priming the database with vnstat -u -i eth0 as root the vnstat process couldn't write to the /var/lib/vnstat/eth0 file as it was running as user "vnstat".

If vnstat is running as user "vnstat" ensure that it has permission to write to /var/lib/vnstat/eth0.

Answer 2

So I was having a similar problem where i was getting the following:

$ vnstat -i eno1

eno1: not enough data available yet

I also tried every other command while pointing to eno1. I would sometimes even get:

Error: Unable to create database backup "/var/lib/vnstat/.eno1" OR Segmentation fault (core dumped)

I tried reinstalling, and everything else under the sun.

Following Andrew's answer to the 't' returned:

Error: Unable to open database "/var/lib/vnstat/eno1" for writing: Permission denied

so instead I did the following, but I'm not sure which one of these commands did the trick.

$ sudo vnstat -i eno1 -u $ sudo vnstat -u -i eno1

Then I checked to see if the interface was working again:

$ sudo vnstat -i eno1

which returned:

> Database updated: Wed Dec 5 10:17:37 2018

(eno1) since 1969-12-31

      rx:  2 KiB      tx:  1 KiB      total:  3 KiB

monthly rx | tx | total | avg. rate ------------------------+-------------+-------------+--------------- Dec '69 2 KiB | 1 KiB | 3 KiB | 0.00 kbit/s ------------------------+-------------+-------------+--------------- estimated -- | -- | -- |

daily rx | tx | total | avg. rate ------------------------+-------------+-------------+--------------- today 2 KiB | 1 KiB | 3 KiB | 0.00 kbit/s ------------------------+-------------+-------------+--------------- estimated -- | -- | -- |

Now its finally able to read and write to eno1 log. I noticed this problem since conky was not showing up any stats reports on today && Month && total. I wasn't expecting anything under month, but after a couple days I was expecting something under hours.

I realise the rest will take a while to populate with data. But now I know for sure it is working. Also, my conky app is finally displaying the information.

However, prior to this solution, I had already chmod the file.

Additional info for newbies such as myself: - make sure to check which interface you are using, I often see solutions for eth0 and others that do not appear when using "$ ifconfig". Enter:

$ ifconfig

and you should see on the left hand side of the results the interface name. Mine are, eno1, lo, and wlo1.

next to the label: "Link encap:" it should say if it is wireless, ethernet, or local loopback

lo is the local loopback a.k.a localhost/127.0.0.1

What I am not sure of, in my case, is the difference between eno1 and wlo1. they both say "Ethernet". I wonder if doesn't have something to do with my direct wifi printer.

Answer 3

When you add the interface for eth0 or ppp0 or whatever, make sure you do it as the vnstat user. ie

sudo -u vnstat vnstat -i ppp0 -u

If you run this as root first you are will have problems even if you chmod the file in /var/lib/vnstat. This is due to the creation of a back file called .ppp0 which you might miss if you are not looking for it. There will be an error in syslog saying that the backup file cannot be written.