Moving up to Centos 7

So I finally upgraded my entire setup to Centos 7 (7.3 to be precise).
Here are some useful notes

By default I do a minimal installation and add what I need. A few extra packages I always add:
epel-release, acpid, net-tools, bash-completion, bash-completion-extras, xauth

ntpd is replaced with chrony. /etc/chrony.conf is the config file and use chronyc sourcestats to see what's going on (equivalent of ntpq --peers)

systemd replaces init.d startup, here are some useful commands. (Because you've installed bash-completion you can hit tab to figure out the service names)

• systemctl start/stop/status <service> (equiv of service start/stop/status)
• systemctl enable/disable <service> (equiv of chkconfig off/on)
• systemctl daemon-reload (if you edit services will reload configs)
• /usr/lib/systemd/system is the dir containing the service definitions
• systemctl list-units
• systemctl list-unit-files (show state of all services, including those that have failed)

firewalld replaces iptables as the default firewall, here's some helpful stuff:

• By default the public profile is active, this is fine add necessary ports to this
• For neatness, if an app needs multiple ports create a service definition and let that through
• New services are created in /etc/firewalld/services
• firewall-cmd --list-all (show current config)
• firewall-cmd --list-services (show only services allowed through firewall)
• firewall-cmd --info-service <service> (show ports in a service)
• firewall-cmd --permanent --add-service=<new service> (add service to config)
• systemctl restart firewalld.service

New default disk format is xfs. Be aware xfs partitions can be grown but not shrunk but the metadata takes less space so are more efficient.

You no longer need to specify -cu options to fdisk, they are now default.

Finally a couple of notes just for the hypervisor:

Install the HP stuff; hp-ams, hp-health & hponcfg

Configure the libvirt-guests service to ensure guests startup & shutdown when the hypervisor does. Ensure the ON_SHUTDOWN=shutdown option is set otherwise guests will suspend which takes an age as it suspends to the USB stick.

rngd is broken and won't start but is easily fixable. Thanks to this website for showing me how.
In essence, the daemon needs "-r /dev/urandom" to tell it to use the correct random device.

When creating your raid configuration in mdadm.conf add MAILADDR <email> as an option to allow mdadm daemon to email you when there is a disk problem. This will also stop the mdmonitor service from throwing a warning on startup.

To import the virtual machines it's better to create them as brand new guests pointing at the original lvm disks rather than importing the xml configs. This will ensure QEMU configures them optimally for Centos 7. The new virt-manager is improved and makes this easy.