DNS is not responsive or cores

  • 7006015
  • 01-May-2012
  • 01-May-2012

Environment

Novell Open Enterprise Server 11 (OES11)
Novell-bind 9.3.3-122.134
Domain Services for Windows
DSfW
Multi-core processors (2 or more cpus)

Situation

DNS is not responsive.  Checking the rcnovell-named status shows unused

namecd, novell-xredg, and micasad are all running and working properly.  When novell-named is restarted, dns starts with out having to restart any other service.

named.run log shows the following:
02-Feb-2012 10:05:15.934 general: server: info:  Failed in getting question name : Checking for StartStop / Dynamic update query
02-Feb-2012 10:05:15.934 general: server: info: Found correct number of counts in header
02-Feb-2012 10:05:15.934 general: server: info: Found that the query is of UDP type
02-Feb-2012 10:05:15.934 general: server: info: Detected as status request
02-Feb-2012 10:05:15.934 general: server: info: Status query : Sending the response was successful
02-Feb-2012 10:05:24.732 general: server: info: shutting down: flushing changes
02-Feb-2012 10:05:24.732 general: control: notice: stopping command channel on 027.0.0.1#953
02-Feb-2012 10:05:24.733 network: interfacemgr: info: no longer listening on 027.0.0.1#53
02-Feb-2012 10:05:24.733 network: interfacemgr: info: no longer listening on 027.0.0.2#53
02-Feb-2012 10:05:24.733 network: interfacemgr: info: no longer listening on 10.10.0.20#53

Resolution

When running DNS server in multi-core processors (2 cpus) two worker threads are created by default and these threads simultaneously load the modified zone data from the eDirectory which will eventually cause the DNS server to hang or even core.

The workaround is to load novell-named in single threaded mode
/opt/novell/named/bin/novell-named -u named -n 1

A new binary that addresses this issue can be obtained through Novell Support.  Reference this TID until the next Maintenance patch is released with the new binary.

Additional Information

When a dynamic reconfiguration runs it finds modified data for a Zone, DNS server locks the zone once the zone update starts and unlock the zone after the completion of in-memory zone DB update.  While the zone is locked, no queries for the locked zone will be answered.

Multi-thread server increases effective utilization of the CPU in the multi-core processor and it is designed to not impact query response during dynamic reconfiguration time.