[nsd-users] NSD database memory usage

Antti Ristimäki antti.ristimaki at csc.fi
Tue Feb 6 09:54:02 UTC 2018

Hi Anand & list,

Actually I forgot to mention it in my first message, but we do have set the database to empty value in configuration.

For us restarting NSD every now and then is not a very big problem, as this instance is only a hidden master, but naturally a more elegant solution would be very welcome.


----- On 6 Feb, 2018, at 11:47, Anand Buddhdev anandb at ripe.net wrote:

> Hi Antti,
> This is certainly a problem, and I'm sure the developers will be happy
> to investigate it with you.
> However, I'd like to suggest that you don't use the database mode. If
> you set:
> database: ""
> in your nsd.conf, then nsd will load the zone from the zonefile into
> RAM, and won't bother compiling the nsd.db file. You don't really gain
> anything with the database file, and I've been advocating for the
> database mode to be dropped completely in future versions of nsd.
> By the way, if you or the developers find the problem, please do let us
> know here, because I'm also curious about it.
> Regards,
> Anand
> On 06/02/2018 09:08, Antti Ristimäki wrote:
>> Hello,
>> We have an installation, where NSD (version 4.1.19) acts as a hidden master for
>> the public DNS servers. NSD has only one large zone configured and the zone is
>> periodically signed every 20 minutes and after each re-signing, "nsd-control
>> reload <zone>" is given so that the NSD process reloads the new zone from the
>> zonefile and notifies the slaves. However, we noticed that the database memory
>> usage increases after every reload, finally resulting in memory allocation
>> failure. We stat the memory usage by running "nsd-control stats_noreset" every
>> minute and in the graph [1] one can see the increase in size.db.mem after each
>> reload. We don't see similar behaviour with for example xfrd process memory
>> usage.
>> We have worked around the issue by restarting the NSD process periodically, but
>> do you have any ideas about the possible root cause and a more long term
>> solution?
>> [1] http://nxdomain.fi/NSD_db_mem.png
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