We all know with RHEL7 or Centos 7.0, the GRUB 2 is introduced.
Lets have a look at the differences between GRUB 1(0.97) and GRUB 2 in Linux.
1. Introduction to GRUB and GRUB2
GRUB 0.97:- Grand Unified Boot Loader is the code that is loaded by our computer system after it is powered on just after our computer’s BIOS(Basic Input Output System, our hardware) completes the POST(Power on Self Test).
GRUB 2:- A complete rewritten GRUB code with additional features. Most of the users not able to notice any differences between GRUB 0.97 & GRUB2, however the new version has fairly many structural modifications and is considered more reliable. The configuration files are stored differently and the modifications or changes to GRUB2 is completely different as compared to GRUB 0.97.
2. Some Notable Differences
|GRUB 0.97||GRUB 2.0|
|Config File||/boot/grub/grub.conf or, /boot/grub/menu.lst||/boot/grub/grub.cfg|
|Partiton Number||Starts from 0||Starts from 1.|
|First device is identified as hd0 in both grub.|
|Display Menu Change||via grub.conf||via /etc/default/grub file|
|Custom Menu||via grub.conf||via /etc/grub.d/40_custom file.|
3. Other Points
1. Grub2 uses UUID to identify a disk, hence it supports LVM and RAID devices.
2. GRUB2 usually shows a login prompt directly and no menu is displayed. We need to press up/down arrow keys or shift key to see the menu.
3. Grub2 helps us to avoid any mis-configuration as update-grub command scans the changes and modify the file. Grub file can easily contain bugs and can cause frequent issues.