[Dnsmasq-discuss] no entries in dnsmasq.leases

Simon Kelley simon at thekelleys.org.uk
Fri Feb 3 12:05:06 GMT 2006

Jens Holze wrote:
> 2006/2/2, Simon Kelley <simon at thekelleys.org.uk>:
>>Jens Holze wrote:
>>>I just tried to reach one of our local computers and realized that its
>>>name wasn't resolved. So I wanted to take a look at the leases and...
>>>Voila, there were non. The leases file is completely empty though it
>>>was updated (timestamp) just a few minutes ago.
>>>I can't remember that I changed anything in the config file and in
>>>fact the server hands out leases (I restarted dnsmasq and then
>>>reconnect some of our machines) via dhcp but he doesn't put them into
>>>the leases files. Anybody ever experienced something comparable?
>>>I use version 2.23 on FC4.
>>Just a thought: is the filesystem full?
> Ouch!
> That was it... My graphical statbar showed 90-95% disk usage but when
> leaving the GUI and asking the command line df told me otherwise. I'm
> terribly sorry for this disturbance.
> What do we learn from this: Don't believe everything GUIs tell you...

It's likely that the filesystem has some space reserved for root. 
Dnsmasq opens the lease file as root, but then changes its UID to a 
non-privileged user before the file gets written. It's an interesting 
question if it therefore gets to use root's quota or not......

It's worth knowing that the lease-file is only ever read at start-up. 
Dnsmasq uses an in-memory copy of the data, and re-writes the file every 
time this changes, so a temporary disk-full should not lose lease 
information as long as some space becomes available to write the file 
before the dnsmasq process exits.

I'll look at making dnsmasq's behaviour more sane under these conditions.



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