RELEASE DATE OF RHEL6 IS 10th NOV 2010.
RELEASE DATE OF RHEL7 IS 10TH JUNE 2014.
Hence RHEL7 is latest os.
DIFFERENCE ON THE BASIS OF OPERATING SYSTEM NAMES
If you want to see this use this command
RHEL6 : REDHAT ENTERPRISE LINUX (SANTIGO)
RHEL7: REDHAT ENTERPRISE LINUX (MAIPO)
 KERNEL VERSION
 OS BOOT TIME
RHEL6: 40 sec
RHEL7: 20 sec
 MAXIMUM SIZE OF SINGLE PARTITION
 BOOT LOADER
 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/hda6
RHEL7: #mkfs.xfs /dev/hda6
 HOW TO REPAIR A FILE SYSTEM IN
RHEL6: #fsck -y /dev/hda6
RHEL7: #xfs_repair /dev/hda6
 COMMAND TO MANAGE NETWORK IN RHEL6 AND RHEL7
 HOSTNAME CONFIGURATION FILE
 DEFAULT ISO IMAGE MOUNT PATH
 FILE SYSTEM CHECK
[14 ]RESIZE A FILE SYSTEM
RHEL6: #resize2fs -p /dev/vg00/lv1
RHEL7: #xfs_growfs /dev/vg00/lv1
 TUNE A FILE SYSTEM
 IPTABLES AND FIREWALL
To see firewall status in RHEL7
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
 INTERFACE NAME
 COMBINING NIC
RHEL6: Network Bonding
RHEL7: Team Driver
 NSF Server Version
 DATABASE USED
Altough RHEL7 also support Mysql
 MANAGING SERVICES
#service sshd restart
#chkconfig sshd on
#chkconfig sshd on
#systemctl restart sshd
#systemctl enable shhd
#systemctl enable shhd
 ON Basis of file System.
RHEL6 defualt file system is ext4 while xfs is RHEL7 default file system.
 Kernel Version
RHEL6 default kernel version is 2.6 while RHEL7 is 3.10
 Kernel Code Name
RHEL6 kernel code name is Santiago while RHEL7 kernel code name is Maipo.
 UID Allocation
In RHEL6 default UID assigned to users would start from 500 while in RHEL7 its 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
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 / while in rhel7 now they are nested under /usr.
NEW FEATURES OF RHEL7 :
1. Space Required to Install 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.
2. Boot Loader in RHEL7
A new book loader GRUB2 has been introduced in RHEL 7.It comes with new features.
3.RHEL7 GRUB2 Configuration File:
# vim /boot/grub2/grub.cfg
4. New Installer you can say Redesigned Anaconda Version
Red Hat Enterprise Linux 7 has and redesigned Anaconda version.
It contains many improvements in system installation.
5. firstboot Implementation
RHRL 7 replaces firstboot with the Initial Setup utility, initial-setup, for better interoperability with the new installer.
6. Changes in File System Layout
RHEL7 introduces two major changes to the layout of the file system.
The /bin, /sbin, /lib and /lib64 directories are now under the /usr directory.
The /tmp directory can now be used as a temporary file storage system (tmpfs)
7. Network Configuration utility(ncat)
A new networking utility ncat has been introduced in RHEL 7 which replaces netcat.
8. New Version of Apache
RHEL 7 is coming with apache 2.4
9. Chrony – A new Package Introduced
Chrony is introduced as new NTP client provided in the chrony package. Chrony does not provides all features available in old ntp client (ntp). So ntp is still provided due to compatibility.
HAProxy has been introduced in RHEL 7. It is a TCP/HTTP reverse proxy that is well-suited to high availability environments.
11.hostname lookup and setup
In rhel5 and rhel6 version of Linux we need to edit file /etc/sysconfig/network to set hostname but in rhel7 its not so.
Now in RHEL7 we can directly chnage the hostname using below commands.
HOW TO SEE HOSTNAME IN RHEL6 and RHEL7
in RHEL6 #hostname
in RHEL7 #hostnamectl status and #hostname
12.Introduction of Docker in RHEL7.
13.Device Hotplug Removed from RHEL7.
14.RHEL7 does not provide 32 bit iso.RHEL7 will not natively support
32-bit hardware architecture.
15.RHEL7 use OPenJDK7 as the default java development kit.
There are other so many changes between RHEL previous versions and RHEL7.
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