RHEL7 uses systemd to manage services and runlevels, with targets replacing traditional runlevels. It uses XFS as the default filesystem which supports larger maximum file and filesystem sizes. Network bonding is called a team driver in RHEL7. Chrony replaces ntp for network time synchronization and Mariadb replaces Mysql as the default database.

1. RHEL6 vs
RHEL7
Beginner’s guide to
differences

2. File System
RHEL7 RHEL6
The Default Filesystem in
RHEL 7 is the XFS
The Default Filesystem in
RHEL 6 is EXT4
Maximum (individual) file
size = 500TB
Maximum filesystem size =
500TB
Maximum (individual) file
size = 16TB
Maximum filesystem size =
16TB
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

3. Run levels
RHEL 7 RHEL 6
Run levels are called targets Traditional run levels or init
/etc/systemd/system/default.targ
et (this by default is linked to the
multi-user target)
the default runlevel would be
defined in /etc/inittab file

4. Run levels
RHEL 7 RHEL 6 Description
runlevel0.target,
poweroff.target
Init 0 Power off the server
runlevel1.target,
rescue.target
Init 1 Set up a rescue shell
runlevel2.target, multi-
user.target
Init 2 Set up a multi-user
non graphical shell
runlevel3.target, multi-
user.target
Init 3 Set up a multi-user
non graphical shell
runlevel5.target,
graphical target
Init 5 Set up a graphical
multi-user system
nunlevel6.target,
reboot.target
Init 6 Reboot the system

5. First Process
RHEL 7 RHEl 6
The first process is systemd
Process id : 1
The first process is init
Process id : 1

6. Hostname Change
RHEL 7 RHEL 6
hostnamectl set-hostname
<new_hostname>
Eg: hostnamectl set-hostname test
hostname <new_hostname>
Eg: hostname test
The hostname has to be changed in
/etc/hostname
The hostname has to be
changed in
/etc/sysconfig/network

7. Enable/Start Service
RHEL 7 RHEL 6
Chkconfig and service is
replaced by systemctl
Chkconfig to enable/disable the
services
Start Service : "systemctl start
nfs-server.service".
Start Service : "service start
nfs" OR "/etc/init.d/nfs start"
Enable Service : To enable the
service (example: nfs service )
to start automatically on boot :
"systemctl enable nfs-
server.service
Enable Service : To start with
specific runlevel : "chkconfig --
level 3 5 nfs on"

8. File System Check
RHEL 7 RHEL 6
xfs_repair
- 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.
e2fsck
- Inode, block, and size checks.
- Directory structure checks.
- Directory connectivity checks.
- Reference count checks.
- Group summary info checks.
XFS does not run a file system
check at boot time.
File system check would gets
executed at boot time

9. UID Allocation
RHEL 7 RHEL 6
By default new users created
would get UIDs assigned
starting from 1000.
Default UID assigned to users
starts from 500
can be changed in
/etc/login.defs if required
can be changed in
/etc/login.defs if required

10. Network Bonding
RHEL 7 RHEL 6
It is termed as Team Driver It is termed as Bonding
/etc/sysconfig/network-scripts/ifcfg-
team0
- DEVICE=”team0”
- DEVICETYPE=”Team”
/etc/sysconfig/network-scripts/ifcfg-
bond0
- DEVICE=”bond0”

11. Network Time Synchronization
RHEL 7 RHEL 6
Uses Chrony suite (faster time
sync compared with ntpd)
Uses ntp

12. Default Database
RHEL 7 RHEL 6
Mariadb is the default
database in RHEL 7
Mysql is the default database
in RHEL 6

13. References
 http://chrony.tuxfamily.org/manual.html#Comparison
-with-ntpd
 http://simplylinuxfaq.blogspot.co.uk/p/major-
difference-between-rhel-7-and-6.html