Re: understanding memory issues

"W.C.A. Wijngaards" <[email protected]> Mon, 2 Jul 2018 15:24:02 +0200
Newsgroups	gmane.network.dns.nsd.general
Message-ID	<[email protected]>
Hi Klaus,

On 02/07/18 15:01, Klaus Darilion wrote:
> Hi!
> 
> We use NSD 4.1.6 as slave for a large zone (2G zone file). It seems
> sometimes the memory is too short:

NSD tries to recover from the cannot allocate memory failure by
performing the update again.  But I guess this also fails (for the same
reason?).  Linux has kernel settings on memory overcommit that allow you
to bypass these limits; since NSD shares most of the memory, also after
fork, and this is not the default assumption of the virtual memory
overcommit heuristic.  But you don't really need to set it I think,
because you can save memory with database: "" and by upgrading.

With NSD 4.1.6 in use one solution is update to the latest, 4.1.22.  Set
database: "" in nsd.conf, that saves about half memory.  Then with the
version upgrade, you can save half memory again on that result, by
--enable-packed at compile time and the selective nsec3 allocations.

Best regards, Wouter

> 
> 03:44:19 nsd[16836]: xfrd: zone xx committed "received update to serial
> 2018063010 at 2018-06-30T03:44:19 from 2a02:850:9::5 TSIG verified with
> key rcode0-distribution"
> 03:45:30 nsd[16837]: rehash of zone xx. with parameters 1 0 5
> 6a0bf229ad0c7a2a
> 03:45:39 nsd[16837]: nsec3 xx 1 %
> 03:46:29 nsd[16837]: zone xx. received update to serial 2018063010 at
> 2018-06-30T03:44:19 from 2a02:850:9::5 TSIG verified with key rcode0-xxx
> of 1717205965 bytes in 324.657 seconds
> 03:46:29 nsd[16837]: fork failed: Cannot allocate memory
> 03:46:32 nsd[16836]: process 16837 exited with status 256
> 03:46:32 nsd[7188]: handle_reload_cmd: reload closed cmd channel
> 03:46:32 nsd[7188]: Reload process 16837 failed, continuing with old
> database
> 03:46:32 nsd[16836]: zone xx serial 2018063009 is updated to 2018063010.
> 
> 
> What confuses me is that since above error all following attemtps to
> transfer and activate the new zone fails, but without any reason.
> 
> 
> 03:51:50 nsd[16836]: xfrd: zone xx committed "received update to serial
> 2018063011 at 2018-06-30T03:51:50 from 2a02:850:9::5 TSIG verified with
> key rcode0-xxx"
> 03:51:58 nsd[16836]: xfrd: zone xx: soa serial 2018063011 update failed,
> restarting transfer (notified zone)
> 03:56:05 nsd[16836]: xfrd: zone xx committed "received update to serial
> 2018063011 at 2018-06-30T03:56:05 from 2a02:850:9::5 TSIG verified with
> key rcode0-xxx"
> 03:56:18 nsd[16836]: xfrd: zone xx: soa serial 2018063011 update failed,
> restarting transfer (notified zone)
> 
> 
> Any idea why NSD is not logging the cause of the "update failed"? I
> guess it is also memory related, or does NSD just not recover from the
> initial "Cannot allocate memory"?
> 
> Thanks
> Klaus
> _______________________________________________
> nsd-users mailing list
> [email protected]
> https://open.nlnetlabs.nl/mailman/listinfo/nsd-users
>

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