RHEL7 and 6 difference

runlevel0.target -> poweroff.target
runlevel1.target -> rescue.target
runlevel2.target -> multi-user.target
runlevel3.target -> multi-user.target
runlevel4.target -> multi-user.target
runlevel5.target -> graphical.target
runlevel6.target -> reboot.target

/etc/systemd/system/default.target (this by default is linked to the multi-user target)

runlevel 0
runlevel 1
runlevel 2
runlevel 3
runlevel 4
runlevel 5
runlevel 6

and the default runlevel would be defined in /etc/inittab file.
/etc/inittab

This could be changed in /etc/login.defs if required.

This could be changed in /etc/login.defs if required.

(This maximum file size is only on 64-bit machines. Red Hat Enterprise Linux does not support XFS on 32-bit machines.)

(This maximum file size is based on a 64-bit machine. On a 32-bit machine, the maximum files size is 8TB.)

XFS does not run a file system check at boot time.

File system check would gets executed at boot time.

– Inode and inode blockmap (addressing) checks.
– Inode allocation map checks.
– Inode size checks.
– Directory checks.
– Pathname checks.
– Link count checks.
– Freemap checks.
– Super block checks.

– Inode, block, and size checks.

– Directory structure checks.

– Directory connectivity checks.

– Reference count checks.

– Group summary info checks.

xfs_growfs takes mount point as arguments.

resize2fs takes logical volume name as arguments.

systemd is a system and service manager for Linux, and replaces SysV and Upstart used in previous releases of Red Hat Enterprise Linux. systemd is compatible with SysV and Linux Standard Base init scripts.

– Start Service : “systemctl start nfs-server.service”.

– Enable Service : To enable the service (example: nfs service ) to start automatically on boot : “systemctl enable nfs-server.service”.

Although one can still use the service and chkconfig commands to start/stop and enable/disable services, respectively, they
are not 100% compatible with the RHEL 7 systemctl command (according to redhat).

– Start Service : “service start nfs” OR “/etc/init.d/nfs start”

– Enable Service : To start with specific runlevel : “chkconfig –level 3 5 nfs on”

The built-in configuration is located under the /usr/lib/firewalld directory. The configuration that you can customize is under the /etc/firewalld directory. It is not possible to use Firewalld and Iptables at the same time. But it is still possible to disable Firewalld and use Iptables as before.

-/etc/sysconfig/network-scripts/ifcfg-team0
– DEVICE=”team0”
– DEVICETYPE=”Team”

-/etc/sysconfig/network-scripts/ifcfg-bond0
– DEVICE=”bond0”