[Pdns-users] Error with master slave replication

Ton van Rosmalen ton at netbase.nl
Thu Aug 27 17:51:14 UTC 2009

Hi Bill,

Bill Pitz schreef:
> Piotr Przybył wrote:
>>> We are having trouble with master/slave replication with a couple of our
>>> large zone files.  This is PDNS-native replication, not database
>>> replication.
>>> Replication is working fine to one of our slaves, but not to the other. 
>>> The broken slave continuously throws these errors when the AXFR of the
>>> zone is attempted from the master:
>> Could you specify if this happens for every zone for this single slave
>> or only for "large" ones?
>> Have you checked if this slave is allowed to do AXFR? Master's config,
>> allow-axfr-ips?
> The problem occurs for the "large" zone.  The smaller zones update
> just fine.
> And yes, this slave is allowed to AXFR -- it retrieved the larger zone
> fine initially, and a few times after that.  Then it stopped.  I set
> up an additional slave and it has the same problem.  As it stands now,
> two of the slaves are in the same datacenter with the master and one
> is in a different facility.  Only the slave in a different facility is
> able to regularly transfer the large zone without issue.  I have a
> feeling that there is some sort of timeout occurring with database
> access when the slave is local, but the remote slave has a natural
> "throttling" due to its distance from the master.
>> You may login to slave machine and try to dig @XX.XX.XX.XX xyzzy.net AXFR
> Yes, manual AXFR requests work from all of the slaves, every time.  No
> errors.
>>> Aug 26 14:46:09 dns2 pdns[16674]: AXFR started for 'xyzzy.net',
>>> transaction started
>>> Aug 26 14:46:31 dns2 pdns[16674]: Unable to AXFR zone 'xyzzy.net' from
>>> remote 'XX.XX.XX.XX': Remote nameserver closed TCP connection
>>> Aug 26 14:46:31 dns2 pdns[16674]: Aborting possible open transaction for
>>> domain 'xyzzy.net' AXFR
>> Take a look at master's logs as well. You may find a reason why it
>> closes the connection.
> I've checked there as well, and unfortunately nothing of interest
> appears in the master's logs, even with logging increased to the maximum.
> Any other ideas?
Is it possible to 'force' the error by issueing a:
dig +tcp @<masternameserver ip> xyzzy.net AXFR

The error indicates a problem in tcp-connections to the supermaster.



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