My oracle web cache notes.
Segfaults all the time
At a customer site, we had the problem that Oracle Web Cache segfaulted all the time (every day) and thus restarted itself. This was evident under high load (more than 1500 connections per second). The Oracle Webcach tracedump looked like this:
<Reason>
Caught SIGSEGV
Error Number: 0
Signal Code: SEGV_MAPERR
Faulting Address: 0x0
</Reason>
It turned out that the kernel parameters where not set (optimally) for oracle web cache. The following steps were needed on this RedHat Enterprise Linux ES release 3 running the RedHat patched 2.4.21 kernel.
# echo 100 32000 100 100 > /proc/sys/kernel/sem
# echo 131072 > /proc/sys/fs/file-max
To make these changes permanent, you need to add them to
/etc/sysctl.conf
# kernel parameters for Oracle Web Cache
kernel.shmall = 2097152
kernel.shmmax = 2147483648
kernel.shmmni = 4096
kernel.sem = 100 32000 100 100
fs.file-max = 131072
net.ipv4.ip_local_port_range = 1024 65000
net.core.rmem_default = 262144
net.core.rmem_max = 262144
net.core.wmem_default = 262144
net.core.wmem_max = 262144
The oracle user also had to have the correct ulimit commands. Be
careful that these are not overridden somewhere else, such
as/etc/bashrc, /home/oracle/.bash_profile or
/home/oracle/.bashrc
ulimit -u 16384 -n 131072
Furthermore, it's important that the
/etc/security/limits.conf allows the user(s)
to set what has been made possible in the above steps (here
it could of course be "oracle" instead of "*".
:
# /etc/security/limits.conf
# Oracle Webcache
* soft nproc 2047
* hard nproc 16384
* soft nofile 2048
* hard nofile 131072
Setting up a new site
-
Site definitions - define your new site
-
Session Binding - you may use the default or add cookie based session binding.
-
Site to Server Mapping - map which servers behind the OWC that shall correspond to the different sites you have defined.
-
caching, personalization ... (the new site may iniherit the settings of former sites).
