Monthly Archives: December 2010

DNS name server, IPv6 and hang of listener

The other day during an operation on one of the DNS servers, some of our RAC listeners went down and stop responding.

We found this happened when they brought down one of the DNS name servers, even thought one was up and running.

Ping, ssh and so on was working fine. But any operation with ‘lsnrctl’ or ‘srvctl xxx listener’ would hang.

After investigation together with the system administrator it was found that it was related to the IPv6 lookups which are activated by default on AIX and are done when the first IPv4 lookup fails.

To solve the problem was just necessary to disable the IPv6 lookups by changing the /etc/netsvc.conf file to:

This is explained on this IBM note.

RDA, AIX, Perl and ulimit 1

The Metalink analyst kept insisting that the “ulimit -d” value was too low.
Running an RDA for Oracle on AIX today I saw that the ulimit values were different if I run on command line or through perl:

$perl -e 'system("ulimit -a");'
time(seconds)        unlimited
file(blocks)         unlimited
data(kbytes)         2097152
stack(kbytes)        unlimited
memory(kbytes)       unlimited
coredump(blocks)     unlimited
nofiles(descriptors) 2000
threads(per process) unlimited
processes(per user)  unlimited

$ulimit -a
core file size        (blocks, -c) unlimited
data seg size         (kbytes, -d) unlimited
file size             (blocks, -f) unlimited
max memory size       (kbytes, -m) unlimited
open files                    (-n) 2000
pipe size          (512 bytes, -p) 64
stack size            (kbytes, -s) unlimited
cpu time             (seconds, -t) unlimited
max user processes            (-u) 2048
virtual memory        (kbytes, -v) unlimited