RHEL 6 vs RHEL 7

RHEL 6 vs RHEL 7 – The Difference Between RHEL 6 and RHEL 7. Here Coding compiler sharing a blog post on key differences between RHEL 6 and RHEL 7. There are many changes from RHEL 6 to RHEL 7 to meet the industry requirements.

When compare RHEL 6 and RHEL 7, Red Hat Enterprise Linux 7 is a Linux-based operating system from Red Hat designed for businesses. RHEL can work on desktops, on servers, in hypervisors or in the cloud. RHEL 7 is very lightweight and container-based.

Difference Between RHEL 6 And RHEL 7

Let’s discuss the different features of RHEL 6 and RHEL 7.

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Default File System

RHEL 6 – Ext4
RHEL 7 – XFS

Kernel Version

RHEL 6 – 2.6.xx
RHEL 7 – 3.10.xx

Release Name

RHEL 6 – Santiago
RHEL 7 – Maipo

Gnome Version

RHEL 6 – GNOME 2
RHEL 7 – GNOME 3.8

KDE Version

RHEL 6 – KDE 4.1
RHEL 7 – KDE 4.6

NFS Version

RHEL 6 – NFS 4
RHEL 7 – NFS 4.1. NFS V2 is deprecated in RHEL 7

Samba Version

RHEL 6 – SMB 3.6
RHEL 7 – SMB 4.4

Default Database

RHEL 6 – MySQL
RHEL 7 – MariaDB

Cluster Resource Manager

RHEL 6 – Rgmanager
RHEL 7 – Pacemaker

Network Interface Grouping

RHEL 6 – Bonding can be done as Active-Backup, XOR, IEEE and Load Balancing
RHEL 7 – Team Driver will support multiple types of Teaming methods called Active-Backup, Load-balancing and Broadcast

KDUMP

RHEL 6 – Kdump does’t support with large RAM Size
RHEL 7 – RHEL 7 can be supported up to 3TB

Boot Loader

RHEL 6 – Grub 2 /boot/grub2/grub.cfg
RHEL 7 – Grub 0.97 /boot/grub/grub.conf

File System Check

RHEL 6 – e2fsck
-Inode check. Block and size check
–Directory Structure check
-Directory Link Check
-reference count check
-Group Summary Check

RHEL 7 – xfs_replair
– Inode blockmap checks
-Inode allocation map checks
-Inode size check
-Directory check
-Path Name check
-Link count check
-Freemap check
-Super block check

Process ID

RHEL 6 – Initd Process ID 1
RHEL 7 – Systemd Process ID 1

Port Security

RHEL 6 – Iptables by default service port is enabled when service is switched on.
RHEL 7 – Firewalld instead of iptables. Iptables can also support with RHEL 7, but we can’t use both of them at the same time. Firewall will not allow any port until and unless you enabled it.

Boot Time

RHEL 6 – 40 Sec
RHEL 7 – 20 Sec

File System Size

RHEL 6 – EXT4 16TB with XFS 100TB
RHEL 7 – XFS 500TB with EXT4 16TB

Processor Architecture

RHEL 6 – 32Bit and 64Bit
RHEL 7 – Only 64Bit

Network Configuration Tool

RHEL 6 – setup
RHEL 7 – nmtui

Hostname Config File

RHEL 6 – /etc/sysconfig/network
RHEL 7 – /etc/hostname No need to edit hostname file to write permanent hostname simply use hostnamectl command

Interface Name

RHEL 6 – eth0
RHEL 7 – ens33xxx

Managing Services

RHEL 6 – service sshd start
service sshd restart
chkconfig sshd on

RHEL 7 – systemctl start sshd.service
systemctl restart sshd.service
systemctl enable sshd.service

System Logs

RHEL 6 – /var/log/
RHEL 7 – /var/log
journalctl

Run Levels

RHEL 6 – runlevel 0 – Power Off
runlevel 1 – Single User Mode
runlevel 2 – Multi User without Networking
runlevel 3 – Multi User CLI
runlevel 4 – Not USed
runlevel 5 – GUI Mode
runlevel 6 – Restart

RHEL 7 – There is no run levels in RHEL 7. Run levels are called as targets
Poweroff.target
rescue.target
multi-user.target
graphical.target
reboot.target

UID Information

RHEL 6 – Normal User UID will start from 500 to 65534
System Users UID will start from 1 to 499

RHEL 7 – Normal User UID start from 1000 – 65534
System Users UID will start from 1 to 999Because Services are increased compare to RHEL 6

By Pass Root Password Prompt

RHEL 6 – append 1 or s or init=/bin/bash to Kernel command line
RHEL 7 – Append rd.break or init=/bin/bash to kernel command line

Rebooting and Poweroff

RHEL 6 – poweroff – init 0
reboot – init 6

RHEL 7 – systemctl poweroff
systemctl reboot

YUM Commands

RHEL 6 -yum groupinstall
yum groupinfo

RHEL 7 – yum group install
yum group info

Extracting Initramfs Image

RHEL 6 – gunzip
gunzip -c /boot/initramfs-$(uname -r).img | cpio -i -d

RHEL 7 – skipcpio
/usr/lib/dracut/skipcpio /boot/initramfs-$(uname -r).img | gunzip -c | cpio -id

Default Inode Size

RHEL 6 – 256 bytes

[root@local ~]# tune2fs -l /dev/sda1|grep -i ‘inode size’

Inode size: 128

RHEL 7 – 512 bytes

[root@managed1 ]# xfs_info /dev/sda1|grep isize

meta-data=/dev/sda1 isize=512 agcount=4, agsize=65536 blks

Iostat Command

Now, in RHEL7.x there is a separate r_await (read await) & w_await (write await) added along with “await” which produces total (changed in sysstat version 10). It is just “await” parameter to get total average time in milliseconds which took to complete IO requests in case of RHEL6.x version.

Network Persistent Device File

RHEL 6 – maintains persistent in network/device
RHEL 7 – maintains persistent in /etc/udev/rules.d/70-persistent-network.rules

Free Command

RHEL 6 – used = total – free
RHEL 7 – used = total – free – buff/cache

Resizing an Lvm

RHEL 6 – EXT family of file systems could be resized if built on a logical volume as a block device.

RHEL 7 – As with XFS file system, resize is not possible.

Dmesg Command

RHEL 6 – “dmesg” command belongs to “util-linux-ng” package and which by default doesn’t record time stamp and hence, data produced doesn’t state when those messages are generated.

RHEL 7 – The new “util-linux” package to which “dmesg” command belongs to can print time-stamp along with messages as storaged in /var/log/dmesg. Now, users can print human readable kernel ring buffer messages using “dmesg -T” command. Most of the user utility commands under /bin are moved to /usr/bin in RHEL7.x architecture.

Sources: Arkit | Simplylinuxfaq

RHEL 6 vs RHEL 7 – Difference Between RHEL 6 And RHEL 7