What are the major differences between RHEL6 RHEL7?

Kernel version

If we want to see in terminal use this command: lsb_release -a or uname -a

RHEL 6: 2.6.32

RHEL 7: 3.0.10

 

OS boot time

RHEL 6: 40 sec

RHEL 7: 20 sec

Command to manage services 

RHEL6:checkconfig

RHEL7:systemctl

Simplified procedures to configure network bonding in RHEL 7.

GUI theme has been changed.

Mainly: Systemd, Base file system (XFS), firewalld, and NetworkManager.

But to be honest the list is much bigger and RHEL7 really introduces great technologies to Enterprise Linux.

Features RHEL7 RHEL6 Default File System XFS EXT4 Kernel Version 3..x-x kernel 2.6.x-x Kernel Kernel Code Name Maipo Santiago General Availability Date of First Major Release (Kernel Version3..0-) (Kernel Version2.6.-) First Process systemd (process ID1) init (process ID1) Runlevel runlevels are called as "targets" as shown below:runlevel0.target -> poweroff.targetrunlevel1.target -> rescue.targetrunlevel2.target -> multi-user.targetrunlevel3.target -> multi-user.targetrunlevel4.target -> multi-user.targetrunlevel5.target -> graphical.targetrunlevel6.target -> reboot.target/etc/systemd/system/default.target (this by default is linked to the multi-user target) Traditional runlevels defined :runlevel0runlevel1runlevel2runlevel3runlevel4runlevel5runlevel6and the default runlevel would be defined in /etc/inittab file./etc/inittab Host Name Change In Red Hat Enterprise Linux7, as part of the move to the new init system (systemd), the hostname variable is defined in /etc/hostname. In Red Hat Enterprise Linux6, the hostname variable was defined in the /etc/sysconfig/network configuration file. Change In UID Allocation By default any new users created would get UIDs assigned starting from.This could be changed in /etc/login.defs if required. Default UID assigned to users would start from.This could be changed in /etc/login.defs if required. Max Supported File Size Maximum (individual) file size =TB Maximum filesystem size =TB (This maximum file size is only on-bit machines. Red Hat Enterprise Linux does not support XFS on-bit machines.) Maximum (individual) file size =TB Maximum filesystem size =TB (This maximum file size is based on a-bit machine. On a-bit machine, the maximum files size is8TB.) File System Check "xfs_repair" XFS does not run a file system check at boot time. "e2fsck" File system check would gets executed at boot time. Differences Between xfs_repair & e2fsck "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. Difference Between xfs_growfs & resize2fs "xfs_growfs"xfs_growfs takes mount point as arguments. "resize2fs"resize2fs takes logical volume name as arguments. Change In File System Structure /bin, /sbin, /lib, and /lib are now nested under /usr. /bin, /sbin, /lib, and /lib are usually under / Boot Loader GRUB2Supports GPT, additional firmware types, including BIOS, EFI and OpenFirmwar. Ability to boot on various file systems (xfs, ext4, ntfs, hfs+, raid, etc) GRUB0. KDUMP RHEL7 supports kdump on large memory based systems up to3 TB Kdump doesn’t work properly with large RAM based systems. System & Service Manager "Systemd"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. Upstart Enable/Start Service For RHEL7, the systemctl command replaces service and chkconfig.- 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% compatible with the RHEL7 systemctl command (according to redhat). Using "service" command and "chkconfig" commands.- Start Service : "service start nfs" OR "/etc/init.d/nfs start"- Enable Service : To start with specific runlevel : "chkconfig --level nfs on" Default Firewall "Firewalld (Dynamic Firewall)"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. Iptables