Sorry for such a basic question but I have to be sure. I will replace my hard drive with new hard drive. Currently I have dual boot (Windows 8.1 and Ubuntu), which boots with GRUB2. Is boot loader only on hard drive? Considering this article it is: http://www.howtogeek.com/187789/dual-booting-explained-how-you-can-have-multiple-operating-systems-on-your-computer/

"Your computer’s operating system is generally installed on its internal hard drive. When you boot your computer, the BIOS loads the boot loader from the hard drive and the boot loader boots the installed operating system."

When hard drive is replaced, new OS can be normally installed? Or do I have to configure some additional stuff before replacing the hard drive?


2 Answers 2


When the computer boots, special code in the read-only memory (BIOS or EFI) reads a boot loader from one of several possible locations (hard disk, USB flash drive, optical drive, network) and gives it control.

  • If you replace the hard disk with a new one, the new disk won't have any boot loader on it; you will need to install an operating system, or else restore a full-system backup. You can use for example Clonezilla to make a full backup of the old hard disk.

  • If you add a hard disk, the old disk still has the boot loader.

P.S. Please read the comment of user waltinator and follow the suggested instructions.


If your /etc/fstab mounts partitions by UUID, e.g.

# /etc/fstab: static file system information.
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    nodev,noexec,nosuid 0       0
# / was on /dev/sda5 during installation
UUID=83a64b80-5a37-4659-b797-221b88ef41f8 /               ext4    errors=remount-ro 0       1
# /home was on /dev/sda6 during installation
UUID=12817b99-9d2b-4357-a4ca-c11eab672a20 /home           ext4    defaults        0       2
# swap was on /dev/sda1 during installation
#UUID=339b7a56-3b67-47e8-87e1-f483296a39bd none            swap    sw              0       0
/dev/mapper/cryptswap1 none swap sw 0 0

You will have to replace the UUIDs of your old disk with the UUIDs of your new disk.

I did this recently, but had to restore the MBR from a different backup. This step is necessary, but not complete.

Run blkid and fix your on-disk fstab while you're booted from the CD/USB key.

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