Moving from Redhat 6 to Redhat 7. There are a *lot* of differences to get use to. It is like having a friend come over and rearrange your entire house, including all the closets and cupboards!! You know it is your house, you just can’t seem to find any of your stuff!
|Features||RHEL 7||RHEL 6|
|Default File System||XFS||EXT4|
|Kernel Version||3.10.x-x kernel||2.6.x-x Kernel|
|Kernel Code Name||Maipo||Santiago|
|General Availability Date of First Major Release||2014-06-09 (Kernel Version 3.10.0-123)||2010-11-09 (Kernel Version 2.6.32-71)|
|First Process||systemd (process ID 1)||init (process ID 1)|
|Runlevel||runlevels are called as “targets” as shown below:runlevel0.target -> poweroff.target
runlevel1.target -> rescue.target
runlevel2.target -> multi-user.target
runlevel3.target -> multi-user.target
runlevel4.target -> multi-user.target
runlevel5.target -> graphical.target
runlevel6.target -> reboot.target
/etc/systemd/system/default.target (this by default is linked to the multi-user target)
|Traditional runlevels defined :runlevel 0
and the default runlevel would be defined in /etc/inittab file.
|Host Name Change||with the move to systemd, the hostname variable is defined in /etc/hostname.||In Red Hat Enterprise Linux 6, 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 1000.This could be changed in /etc/login.defs if required.||Default UID assigned to users would start from 500.
This could be changed in /etc/login.defs if required.
|Max Supported File Size||Maximum (individual) file size = 500TBMaximum filesystem size = 500TB(This maximum file size is only on 64-bit machines. Red Hat Enterprise Linux does not support XFS on 32-bit machines.)||Maximum (individual) file size = 16TBMaximum filesystem size = 16TB(This maximum file size is based on a 64-bit machine. On a 32-bit machine, the maximum files size is 8TB.)|
|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 /lib64 are now nested under /usr.||/bin, /sbin, /lib, and /lib64 are usually under /|
|Boot Loader||GRUB 2Supports GPT, additional firmware types, including BIOS, EFI and OpenFirmwar. Ability to boot on various file systems (xfs, ext4, ntfs, hfs+, raid, etc)||GRUB 0.97|
|KDUMP||Supports kdump on large memory based systems up to 3 TB||Kdump doesn’t work properly with large RAM based systems.|
|System & Service Manager||“Systemd”systemd is compatible with the SysV and Linux Standard Base init scripts it replaces.||Upstart|
|Enable/Start Service||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 100% compatible with the RHEL 7 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 3 5 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|
|Network Bonding||“Team Driver”-/etc/sysconfig/network-scripts/ifcfg-team0
|Network Time Synchronization||Using Chrony suite (faster time sync compared with ntpd)||Using ntpd|
|NFS||NFS4.1NFSv2 is no longer supported. Red Hat Enterprise Linux 7 supports NFSv3, NFSv4.0, and NVSv4.1 clients.||NFS4|
|Cluster Resource Manager||Pacemaker||Rgmanager|
|Load Balancer Technology||Keepalived and HAProxy||Piranha|
|Desktop/GUI Interface||GNOME3 and KDE 4.10||GNOME2|
|Default Database||MariaDB is the default implementation of MySQL||MySQL|
|Managing Temporary Files||systemd-tmpfiles (more structured, and configurable, method to manage tmp files and directories).||Using “tmpwatch”|