Symptoms

PowerDNS server hangs frequently and does not update DNS zones until the pdns service is manually restarted.

/var/log/messages contains the following:

hsp pdns[14516]: Got a signal 11, attempting to print trace:
hsp pdns[14516]: [0x4732b0]
hsp pdns[14516]: [0x625290]
hsp pdns[22917]: Our pdns instance (14516) exited after signal 6

OBAS is running inside a Virtuozzo container.

Cause

Signal 11 is SIGSEGV - "Invalid memory reference".

1. Check User Beancounters inside OBAS container:

   [root@OBASct ~]# cat /proc/user_beancounters
   

2. If failcnt equal to zero for all resources, the issue can be caused by the physical memory troubles.

Resolution

1. If failcnt for some resources is not equal to zero, please increase appropriate limits using the following command on the Virtuozzo node:

   [root@VZnode ~]# vzctl set <ct_id> --save --<recource_name> NEW_BARRIER:NEW_LIMIT
   

   where <ct_id> is the ID of the OBAS container, and <resource_name> is the name of resource that have non-zero failcnt

2. Check physical memory with some testing tool like Memtest86+