Cluster 1. HP DL380p Gen8 initial setup using Intelligent Provisioning: iLO4 & other firmware upgrade, host system (CentOS7) installation.

Minimum requirements concerning hardware servers:

• Two servers with the following;
• A CPU with hardware-accelerated virtualization
• Redundant power supplies
• IPMI or vendor-specific out-of-band management, like Fujitsu's iRMC, HP's iLO, Dell's iDRAC, etc
• Four network interfaces, 1 Gbit or faster
• 2 GiB of RAM and 44.5 GiB of storage for the host operating system, plus sufficient RAM and storage for your VMs
• Two network switches - also you can interconnect network cables between both servers.

Technologies We Will Use while setting cluster up:

• Red Hat Enterprise Linux 7
• Red Hat Cluster Services:
• Cluster Manager (corosync); Manages the starting, stopping and managing of the cluster.
• Resource Manager (pacemaker); Manages cluster resources and services. Handles service recovery during failures.
• Clustered Logical Volume Manager (clvm); Cluster-aware (disk) volume manager (backs GFS2 filesystems and KVM virtual machines).
• Global File System version 2 (gfs2); Cluster-aware, concurrently mountable file system.
• Distributed Redundant Block Device (DRBD); Keeps shared data synchronized across cluster nodes.
• KVM; Hypervisor that controls and supports virtual machines.

Upgrading iLO4 & other firmware

Insert cable to the desired NIC port of the server. After powering server on, wait until this appears:

Press F10. 

Choose "Perform Maintenance", then "Intelligent Provisioning Preferences" here you can verify an IP address assigned via DHCP (if DHCP is used) or assign an IP manually (cable connected port is shown as tick in a green circle). This IP must have privilege to access the Internet. After verifying/assigning an IP  go back and choose "Firmware update" (If you want to view verified packets and download status during firmware updates availability testing - click "More"). All available packets will be shown and then you can choose needed updates and install them.
By default only IP address is assigned to the iLO via DHCP and no DNS or Default Gateway. To fix that access "iLO Configuration" ("Intelligent Provisioning" -> "Perform Maintenance"),  and check those below:

also disable IPv6 if you don't need it:

 Accessing iLO4

Insert network cable to the servers iLO port.

On the picture above you can see IPv4 which is assigned to the iLO via DHCP server. If you have firewall - give that IP permission to access the Internet (Internet access is needed in order to register your server). Access iLO via https://iLO_IPv4. Default User-name and Password are on the bottom of the tag on the front of the server:

Verify that "Administration" -> "Access Settings" -> "IPMI/DCMI over LAN Access" is "Enabled.
I don't exactly know why we need to assign iLO4 DNS Name, but I've assigned it (iLO DNS Name can be found on the same tag).
If you done some changes in a iLO4 Web GUI - you must to "Reset" iLO. This can be done either in the tab where you done changes, or via "Information" -> "Diagnostics" -> "Reset iLO"

Host system (CentOS7) installation

After upgrading firmware and verifying access to the iLO4, go to "Configure and Install" of the "Intelligent Provisioning":

  

 

Insert CentOS7 installation DVD into server's optical drive. 
Then:

Manual is selected because CentOS7 is not distinctly RHEL and  CentOS7 installation  media is not recognized by HP Intelligent Provisioning.

After hitting "Continue" HP Drivers related Warning message is shown, ignore this message and accept. After reboot CentOS7 installation will start and you'll see all HP RAID Logical Disks.

PS
On one of my servers IP (Intelligent Provisioning) is not working and I installed OS using USB Flash:

1. Download CentOS 7
2. lsblk -a #find a proper USB Flash i.e. /dev/sdb
3. fdisk /dev/sdb #create partition if no one exists
4. lsblk -a # find created partition label i.e. /dev/sdb1
5. mkfs.fat /dev/sdb1 or mkfs.vfat /dev/sdb1
6. Write downloaded CentOS 7 iso to the USB Flash (use only disk label, not partition label):
1. dd if=CentOS-7-x86_64-Minimal-1708.iso of=/dev/sdb #NOT /dev/sdb1
7. Install
8. Set amount of space needed for VM's on both servers (i.e. you assume to have 100GB space for VM's on one server and 150GB on the other, sum=100+150=250) as raw device/partition, this will save you much time when setting up clustered storage