Oracle Express Edition 11 (Oracle XE 11)
experiences and recommendations

I used it as a server with openSUSE linux for the past years, but now i prefer to use Oracle Linux.

Oracle Linux 5 is no more available, respectively it is not supported anymore.

If you intend to use Oracle Linux 6 (ol6) or Oracle Linux 7 (ol7), install  'oracle-rdbms-server-11gR2-preinstall'.
     [root@ol7  ~]   yum install oracle-rdbms-server-11gR2-preinstall

After that remove the user 'oracle' and the groups 'dba' and 'oinstall', they point to the directory /home/oracle.
      [root@ol7  ~]  userdel -r oracle
                             groupdel dba
                             groupdel oinstall

This will install additional linux packages and set all necessary values, appending to the files:
     /etc/sysctl.conf:

       # Controls the default maxmimum size of a mesage queue
       kernel.msgmnb = 65536
       # Controls the maximum size of a message, in bytes
       kernel.msgmax = 65536
       # Controls the maximum shared segment size, in bytes
       # Controls the maximum number of shared memory segments, in pages
       # oracle-rdbms-server-11gR2-preinstall setting for fs.file-max is 6815744
       fs.file-max = 6815744
       # oracle-rdbms-server-11gR2-preinstall setting for kernel.sem is '250 32000 100 128'
       kernel.sem = 250 32000 100 128
       # oracle-rdbms-server-11gR2-preinstall setting for kernel.shmmni is 4096
       kernel.shmmni = 4096
       # oracle-rdbms-server-11gR2-preinstall setting for kernel.shmall is 1073741824 on x86_64 and 2097152 on i386
       kernel.shmall = 4294967296
       # oracle-rdbms-server-11gR2-preinstall setting for kernel.shmmax is 4398046511104 on x86_64 and 4294967295 on i386
       kernel.shmmax = 4398046511104
       # oracle-rdbms-server-11gR2-preinstall setting for kernel.panic_on_oops is 1
       kernel.panic_on_oops = 1
       # oracle-rdbms-server-11gR2-preinstall setting for net.core.rmem_default is 262144
       net.core.rmem_default = 262144
       # oracle-rdbms-server-11gR2-preinstall setting for net.core.rmem_max is 4194304
       net.core.rmem_max = 4194304
       # oracle-rdbms-server-11gR2-preinstall setting for net.core.wmem_default is 262144
       net.core.wmem_default = 262144
       # oracle-rdbms-server-11gR2-preinstall setting for net.core.wmem_max is 1048576
       net.core.wmem_max = 1048576
       # oracle-rdbms-server-11gR2-preinstall setting for net.ipv4.conf.all.rp_filter is 2
       net.ipv4.conf.all.rp_filter = 2
       # oracle-rdbms-server-11gR2-preinstall setting for net.ipv4.conf.default.rp_filter is 2
       net.ipv4.conf.default.rp_filter = 2
       # oracle-rdbms-server-11gR2-preinstall setting for fs.aio-max-nr is 1048576
       fs.aio-max-nr = 1048576
       # oracle-rdbms-server-11gR2-preinstall setting for net.ipv4.ip_local_port_range is 9000 65500
       net.ipv4.ip_local_port_range = 9000 65500

     maybe increase:
        fs.aio-max-nr = 2097152
        fs-aio-nr = 34076


     /etc/security/limits.conf:

       # oracle-rdbms-server-11gR2-preinstall setting for nofile soft limit is 1024
       oracle soft nofile 1024
       # oracle-rdbms-server-11gR2-preinstall setting for nofile hard limit is 65536
       oracle hard nofile 65536
       # oracle-rdbms-server-11gR2-preinstall setting for nproc soft limit is 16384
       # refer orabug15971421 for more info.
       oracle soft nproc 16384
       # oracle-rdbms-server-11gR2-preinstall setting for nproc hard limit is 16384
       oracle hard nproc 16384
       # oracle-rdbms-server-11gR2-preinstall setting for stack soft limit is 10240KB
       oracle soft stack 10240
       # oracle-rdbms-server-11gR2-preinstall setting for stack hard limit is 32768KB
       oracle hard stack 32768
       # oracle-rdbms-server-11gR2-preinstall setting for memlock hard limit is maximum of 128GB on x86_64 or 3GB on x86 OR 90 % of RAM
       oracle hard memlock 134217728
       # oracle-rdbms-server-11gR2-preinstall setting for memlock soft limit is maximum of 128GB on x86_64 or 3GB on x86 OR 90 % of RAM
       oracle soft memlock 134217728

     /etc/pam.d/login             (in OL6)
     /etc/pam.d/system-auth  (in OL7)

       session required pam_limits.so

     /etc/sysconfig/network
        # oracle-rdbms-server-11gR2-preinstall : Add NOZEROCONF=yes
        NOZEROCONF=yes
        # in openSUSE it is placed in /etc/sysconfig/network/config

Kernel parameters are added:
       numa=off
       transparent_hugepage=never

#openSUSE:
Add  'numa=off' and 'transparent_hugepage=never' to  '/boot/grub/grub.conf' (ol6)  respectively to  '/etc/default/grub' (ol7)
start 'grub2-mkconfig -o /boot/grub2/grub.cfg' on the command line.

If you intend to use openSUSE, you can append these values to all these files.

The installation of  'Oracle Express Edition 11' will add the user 'oracle' with group 'dba' and will use the directory /u01/app/oracle

Setup your network / network interface to a fixed IP-address, the installation will query  '/etc/hosts' for a valid entry.
ol6:  system-config-network
ol7:  nmtui
openSUSE: yast2 lan

Your '/etc/hosts' should look like:
     127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
     ::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
     192.168.10.1 ol6.localdomain ol6

     /etc/oratab:

       XE:/u01/app/oracle/product/11.2.0/xe:N

ORACLE_HOME=/u01/app/oracle