Difference between revisions of "Grub"
From Briki
(→Moving boot record and /boot to a new disk) |
(→Moving root partition to a new disk) |
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== Moving boot record and /boot to a new disk == | == Moving boot record and /boot to a new disk == | ||
* Setup new disk with GPT partition table | * Setup new disk with GPT partition table | ||
| − | * For BIOS (not EFI) booting, create a ~ | + | * For BIOS (not EFI) booting, create a ~2MB partition at the start of the disk, with the bios_grub flag |
| + | sudo parted -a optimal -s /dev/sdX -- mklabel gpt mkpart bios 0% 2MB set 1 bios_grub on | ||
* Create a boot partition (but don't set the boot flag) | * Create a boot partition (but don't set the boot flag) | ||
| + | sudo parted -a optimal -s /dev/sdX -- mkpart boot 2MB 5GB | ||
| + | sudo mkfs.ext4 /dev/sdX2 | ||
* Use the remainder of the space as desired | * Use the remainder of the space as desired | ||
* Example "parted /dev/sdX -- print free" for a bootable drive: | * Example "parted /dev/sdX -- print free" for a bootable drive: | ||
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</pre> | </pre> | ||
* Restart (or halt and disconnect old drive), and cross your fingers! | * Restart (or halt and disconnect old drive), and cross your fingers! | ||
| + | |||
| + | == Updating /boot/grub/device.map == | ||
| + | This file is no longer generated (or kept up to date) by default in recent grub versions, since it's largely unused. To update it manually: | ||
| + | sudo grub-mkdevicemap | ||
| + | |||
| + | == Moving root partition to a new disk == | ||
| + | https://superuser.com/questions/615956/how-can-i-specify-a-different-disk-to-be-root-in-grub-cfg-when-running-grub-mkco | ||
| + | |||
| + | Ensure you also change the boot order in your motherboard BIOS if you've installed the boot sector to a new drive. | ||
Latest revision as of 20:19, 4 February 2021
Moving boot record and /boot to a new disk
- Setup new disk with GPT partition table
- For BIOS (not EFI) booting, create a ~2MB partition at the start of the disk, with the bios_grub flag
sudo parted -a optimal -s /dev/sdX -- mklabel gpt mkpart bios 0% 2MB set 1 bios_grub on
- Create a boot partition (but don't set the boot flag)
sudo parted -a optimal -s /dev/sdX -- mkpart boot 2MB 5GB sudo mkfs.ext4 /dev/sdX2
- Use the remainder of the space as desired
- Example "parted /dev/sdX -- print free" for a bootable drive:
Model: ATA ST3320620A (scsi)
Disk /dev/sde: 320GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name Flags
1 17.4kB 1049kB 1031kB bios bios_grub
2 1049kB 2000MB 1999MB ext4 boot
3 2000MB 320GB 318GB ext4 tmp
320GB 320GB 335kB Free Space
- Mount new boot partition at /mnt, and copy boot partition onto it:
mount /dev/sdXY /mnt cp -a /boot/* /mnt
- Edit /etc/fstab and change /boot partition mount to UUID for new partition (use /dev/disk/by-uuid to determine partition uuid)
- Unmount existing /boot, and mount new /boot
umount /boot mount /boot
- Install grub boot loader into the bios partition, using the /boot partition for OS loading. Note that the disk is specified, rather than a partition:
grub-install /dev/sdX
- Update grub to match the new partition layout:
update-grub
- Restart (or halt and disconnect old drive), and cross your fingers!
Updating /boot/grub/device.map
This file is no longer generated (or kept up to date) by default in recent grub versions, since it's largely unused. To update it manually:
sudo grub-mkdevicemap
Moving root partition to a new disk
Ensure you also change the boot order in your motherboard BIOS if you've installed the boot sector to a new drive.
