What is Difference Between RHEL 6 & RHEL 7

OS BOOT TIME
RHEL6: 40 sec

RHEL7: 20 sec

MAXIMUM SIZE OF SINGLE PARTITION
RHEL6: 50TB(EXT4)

RHEL7: 500TB(XFS)

BOOT LOADER
RHEL6:  /boot/grub/grub.conf

RHEL7: /boot/grupb2/grub.cfg

PROCESSOR ARCHITECTURE
RHEL6: It support 32bit & 64bit both

RHEL7: It only support 64bit

HOW TO FORMAT OR ASSIGN A FILE SYSTEM IN
RHEL6:      #mkfs.ext4   /dev/hda4

RHEL7:       #mkfs.xfs   /dev/hda3

HOW TO REPAIR A FILE SYSTEM IN
RHEL6:  #fsck -y /dev/hda3

RHEL7:  #xfs_repair /dev/hda3

COMMAND TO MANAGE NETWORK IN RHEL6 AND RHEL7
RHEL6:  #setup

RHEL7:  #nmtui

HOSTNAME CONFIGURATION FILE
RHEL6:    /etc/sysconfig/network

RHEL7:    /etc/hostname

DEFAULT ISO IMAGE MOUNT PATH
RHEL6: /media

RHEL7: /run/media/root

FILE SYSTEM CHECK
RHEL6:   e2fsck

RHEL7:   xfs_repair

RESIZE A FILE SYSTEM
RHEL6:   #resize2fs -p /dev/vg00/lv1

RHEL7:    #xfs_growfs  /dev/vg00/lv1

TUNE A FILE SYSTEM
RHEL6: tune2fs

RHEL7: xfs_admin

IPTABLES AND FIREWALL
RHEL6: iptables

RHEL7: firewalld

IPtables
To see firewall status in RHEL7

#firewall-cmd   –state

To see Firewall status in RHEL6

#service iptables status

To stop firewall in RHEL7

#systemctl stop firewalld.service

To stop firewall in RHEL6

#service iptables stop

COMMUNICATION BETWEEN TCP AND UDP IN BACK END
RHEL6: netcat

RHEL7: ncat

INTERFACE NAME
RHEL6: eth0

RHEL7: ens198(N)

COMBINING NIC
RHEL6: Network Bonding

RHEL7: Team Driver

NSF Server Version
RHEL6:  NFSv2

RHEL7:  NFSV4

DATABASE USED
RHEL6: Mysql

RHEL7: mariaDB

RHEL7 also support Mysql

MANAGING SERVICES
RHEL6:

#service sshd restart

#chkconfig sshd on

RHEL7:

#systemctl restart sshd

#systemctl enable shhd

File System.
RHEL6 default file system is ext4

xfs is RHEL7 default file system.

Kernel Version
RHEL6 default kernel version is 2.6 while RHEL7 is 3.10

UID Allocation
In RHEL6 default UID assigned to users would start from 500 while in RHEL7 it’s starting from 1000.
But this can be changed if required by editing /etc/login.defs file.

Maximum supported File Size.
In RHEL6 maximum file size of an individual file can be up to 16TB while in RHEL7 it can be up to 500TB which is very large in comparison to RHEL6.

Maximum Supported File System Size.
In RHEL6 maximum file system size=16TB (for 64bit Machine) and 8TB (for 32 bit machine). While in RHEL7 maximum file system size is 500TB.

Also keep in mind that RHEL does not support XFS on 32-bit machines.

Change in file system structure.
In rhel6 /bin,/sbin,/lib and /lib64 are usually under /

In rhel7, now /bin,/sbin,/lib and /lib64 are nested under /usr.

The /tmp directory can now be used as a temporary file storage system (tmpfs)

Space Required to Installing RHEL7?

Now if you want to install RHEL7 in your machine, RedHat recommends minimum 5 GB of disk space to install this release of RHEL series for all supported architectures.

.Hostname lookup and setup
In rhel5 and rhel6 versions, we can edit file /etc/sysconfig/network to set hostname but in rhel7 we can directly change the hostname using below commands.

hostnamectl
nmtui
nmcli
Example:

in RHEL6              #hostname

in RHEL7              #hostnamectl  status   and #hostname

Few More notable changes in RHEL 7.
Netstat and ifconfig commands also disappeared from RHEL7 but it can be used by installing net-tools.
The move from sysvinit to systemd is one of most important change that has been made and which is a matter of concerned.
Command tail -n is replaced by journalctl -n
Command tail -f is replaced by journalctl -f
For displaying kernel messages instead of dmesg now in RHEL7 we use journalctl –k