A have switched flapping detection off and after that nagios works just fine. <div class="noTransl"> Quoting Ton Voon <<a href="mailto:ton.voon@altinity.com">ton.voon@altinity.com</a>>:</div> <blockquote style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">On 31 Mar 2006, at 10:06, Vadim Korsak wrote: <blockquote style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Nagios 2.1 have stopped some times. Last entry in log till it stops - SERVICE FLAPPING ALERT: grep -B 1 "2.1 starting..." /var/log/nagios/nagios.log [1143723946] SERVICE FLAPPING ALERT: _net-n-liepaja-srv;DISK C: free space;STARTED; Service appears to have started flapping (20.5% change >= 20.0% threshold) [1143790405] Nagios 2.1 starting... (PID=6671) -- [1143792340] SERVICE FLAPPING ALERT: _net-n-liepaja-srv;DISK C: free space;STARTED; Service appears to have started flapping (21.1% change >= 20.0% threshold) [1143792757] Nagios 2.1 starting... (PID=11656) -- [1143793487] SERVICE FLAPPING ALERT: _net-n-liepaja-srv;DISK C: free space;STARTED; Service appears to have started flapping (21.6% change >= 20.0% threshold) [1143793561] Nagios 2.1 starting... (PID=24024) -- [1143794252] SERVICE FLAPPING ALERT: _net-n-liepaja-gw;PING gateway;STARTED; Service appears to have started flapping (24.2% change >= 20.0% threshold) [1143794282] Nagios 2.1 starting... (PID=2723) -- [1143795613] SERVICE FLAPPING ALERT: _net-n-liepaja-srv;DISK C: free space;STARTED; Service appears to have started flapping (21.3% change >= 20.0% threshold) [1143795722] Nagios 2.1 starting... (PID=27191) Nagios itself starts flapping ;) </blockquote> Vadim, Which platform are you running on? Which configure options did you build with? When it happens again, can you send a pstree output (want to see if nagios has forked other processes - maybe hanging on an external command). For each nagios process, can you run an strace to see what bit of the code it is currently hanging on. Ton http://www.altinity.com T: +44 (0)870 787 9243 F: +44 (0)845 280 1725 Skype: tonvoon </blockquote> <div id="sig"> </div>