Linux

udev rules (for ASM) :

ENV{DM_VG_NAME}=="oradisksASM" ENV{DM_LV_NAME}=="DISK*" OWNER="oracle" GROUP="dba"

LVM :

lvdisplay --noheadings --units m -C -o Size /dev/db2vg/lv_RAW01

OpenSSL file encryption :

openssl aes-256-cbc -a -salt -in secrets.txt -out secrets.txt.enc

OpenSSL file decryption :

openssl aes-256-cbc -d -a -in secrets.txt.enc -out secrets.txt.new

Install components [ALL NODES] :

yum -y install pcs pacemaker fence-agents-all

Set password of user hacluster [ALL NODES] :

passwd hacluster

Enable services [ALL NODES] :

systemctl start pcsd.service
systemctl enable pcsd.service

Create authentication tokens [FROM PRIM. NODE] :

pcs cluster auth dbp04allx.unixguest.eu dbp26allx.unixguest.eu dbp05allx.unixguest.eu

Create cluster [FROM PRIM. NODE] :

pcs cluster setup --start --name HADR_ISM dbp04allx.unixguest.eu dbp26allx.unixguest.eu dbp05allx.unixguest.eu

Enable cluster services on boot [FROM PRIM. NODE] :

pcs cluster enable --all

You can list services in Linux as follows:

[root@tain-cx-uatdb1 ~]# systemctl list-unit-files
UNIT FILE                                     STATE
proc-sys-fs-binfmt_misc.automount             static
dev-hugepages.mount                           static
dev-mqueue.mount                              static
proc-fs-nfsd.mount                            static
proc-sys-fs-binfmt_misc.mount                 static
sys-fs-fuse-connections.mount                 static
sys-kernel-config.mount                       static
sys-kernel-debug.mount                        static
tmp.mount                                     disabled
var-lib-nfs-rpc_pipefs.mount                  static
brandbot.path                                 enabled
systemd-ask-password-console.path             static
systemd-ask-password-plymouth.path            static
systemd-ask-password-wall.path                static
session-1.scope                               static
session-29975.scope                           static
session-29979.scope                           static
acpid.service                                 enabled
arp-ethers.service                            disabled
auditd.service                                enabled
auth-rpcgss-module.service                    static
autofs.service                                disabled

We can check if a process is making connection from outside as follows:

[root@ag-se-tlcasdb1 ~]#  lsof -i -a -p 4970
COMMAND  PID   USER   FD   TYPE   DEVICE SIZE/OFF NODE NAME
oracle  4970 oracle   16u  IPv6 37827976      0t0  TCP ag-se-tlcasdb1.net.tain.com:ncube-lm->172.25.2.12:43612 (ESTABLISHED)

As we can see, that is very useful for oracle processes. When the connection HAS to create process also ON the local server.