[Samba] BIND9.8 DLZ performance issue

Arthur Ramsey arthur_ramsey at mediture.com
Thu Sep 29 15:16:14 UTC 2016


I'm running Samba 4.5.0 and bind-9.8.2-0.47.rc1.el6_8.1.  One DC of 
four, the PDC, is magnitudes slower running 
/usr/local/samba/sbin/samba_dnsupdate --verbose --all-names.  When that 
is running on that DC it seems to block any queries.  The load average 
is usually under 0.5.  The DC was unsafely halted, which could have 
corrupted something.  I ran a dbcheck with samba-tool and it came back 
clean other than the expected cleanup after upgrading to 4.5.0.  Is 
there any caches or similar that I could try clearing for BIND?  Usually 
at least once a day the memory increases from the typical ~1 GB of usage 
to everything the box has, 8 GB physical and 10 GB swap, requiring a 
forceful restart, so there appears to be a memory leak as well.  When 
memory usage is high, it is from smbd process, which I wouldn't think 
would have a correlation to BIND.  Rather than a memory leak, the 
blocking seen with DNS queries is also blocking smb clients resulting in 
a pile of connections and high memory usage? The load under this 
condition is very high, but that is due to high IO and CPU usage from 
swapping.  I had similar behavior with 4.4.5, but it was fine for the 
first couple of weeks after upgrade.


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