Oracle Web Cache |

Oracle Web Cache

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:

Error Number: 0
Signal Code: SEGV_MAPERR
Faulting Address: 0x0

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

  1. Site definitions - define your new site

  2. Session Binding - you may use the default or add cookie based session binding.

  3. Site to Server Mapping - map which servers behind the OWC that shall correspond to the different sites you have defined.

  4. caching, personalization ... (the new site may iniherit the settings of former sites).

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