[nsd-users] xfrd process not starting

Martin Svec martin.svec at zoner.cz
Tue Jan 24 19:58:56 UTC 2012

Hello John,

our NSD servers run about 100k zones and we had a number of 
problems with xfrd too -- terribly high cpu usage during 
reloads, waste of memory, etc. I sent few reports and 
patches about these problems in 2010, see e.g. 
But finally I realized that xfrd code cannot be easily 
adapted for such a large number of zones and decided to 
disable it at all. Because most of our DNS operations 
involve adding or removing a zone, we created our own 
synchronization that simply distributes compiled nsd.db 
among nameservers and so xfrd is useless for us.

Attached I send you our patch to disable xfrd in nsd-3.2.9. 
It's a dirty single-purpose hack but our nameservers run 
with it nearly 2 years.

I'd like to see an official option to disable xfrd 
functionality too, but I'm too busy to create a patch that 
would be suitable for upstream.

You can also try --enable-mmap configure option that 
replaces malloc-based allocator with mmap-based allocator 
for zone data. It's primary goal is to address excessive 
memory usage of xfrd, see my post in the list archive. It's 
marked as experimental but we have it enabled since March 
2010 without issues.


Dne 24.1.2012 17:46, John Peacock napsal(a):
> I have an instance of nsd running with 50k domains (each with only 6
> records) and I get a less continuous output to the log file of:
> [1324495953] nsd[14256]: error: malloc failed: Cannot allocate memory
> [1324495954] nsd[22167]: warning: xfrd process 14256 failed with status
> 256, restarting
> This is even though there is ~3G free RAM on that box.
> This nsd instance is never going to either receive an xfr request nor
> send notify to another instance.  It is strictly the single
> authoritative server for these domains (they are for e-mail testing, if
> it matters).  Is there any way to disable the xfrd functionality
> completely?  Or do I have to go through and patch the source code to not
> spawn that child process?
> John
> _______________________________________________
> nsd-users mailing list
> nsd-users at NLnetLabs.nl
> http://open.nlnetlabs.nl/mailman/listinfo/nsd-users

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