How to migrate boot partition to other storage disk partition in RHEL

Solution Verified - Updated 13 Nov 2025

Environment

Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 8
Red Hat Enterprise Linux 9
Red Hat Enterprise Linux 10

Issue

Storage migration is in progress, and need to move smaller /boot partition to some another disk containing larger partition for /boot
How to migrate the data from /boot to some other higher storage capacity first partition of another disk and make it bootable?
Need information on changing the /boot partition to a different disk

Resolution

Red Hat does not support planned migrations where the boot location is changed

The supported method to change the boot method is to use the Anaconda installer in the regular Red Hat Enterprise Linux installation process to reinstall the OS onto the new boot target.

The supported procedure is covered by the following resources:

An unsupported solution is provided below (it's unsupported because there is no formal guarantee it will work, depending on the hardware).

Unsupported Disclaimer

The following information has been provided by Red Hat, but is outside the scope of the posted Service Level Agreements and support procedures (Production Support - Red Hat Customer Portal). The information is provided as-is and any configuration settings or installed applications made from the information in this article could make the Operating System unsupported by Red Hat Global Support Services. The intent of this article is to provide information to accomplish the system's needs. Use of the information in this article at the user's own risk.

Workaround Instructions

Note: Please make sure to have a backup of data before applying these steps on the production server, since unforeseen issues may occur.

Let assume two disks: /dev/sda and /dev/sdb.
Steps to migrate the /boot partition from /dev/sda to a new device /dev/sdb.

First we create the new /dev/sdb1 partition on /dev/sdb

We also need to make sure that we have a post-MBR gap (unallocated space) where grub will be installed. We will leave 1MiB of unallocated space at the start of the device which is the size used during installation. If there is no partition table on this device, create it:
```
 # parted /dev/sdb mklabel msdos
```
Note: Please make sure that there is no data present on disk /dev/sdb, as the following procedure will re-create a new disk label on it and a new partition will be created on disk /dev/sdb, thus it would erase any previous data present on it.

Create the partition:
```
 # parted /dev/sdb mkpart p xfs 1MiB 1024MiB
```

Format the new partition with a filesystem

 # mkfs.xfs /dev/sdb1
 Or
 # fdisk /dev/sdb
 [...]

Mount the filesystem on /mnt and copy files from /boot
```
 # mount /dev/sdb1 /mnt
 # cp -a /boot/* /mnt/
```
Unmount both file systems

On BIOS systems:
```
 # umount /mnt /boot
```
On UEFI systems:
Ref: How to determine if the system is booted in BIOS or UEFI mode
```
 # umount /mnt /boot/efi /boot
```
Update /etc/fstab

Change the relevant entry for the boot filesystem so that it uses the new partition. If you are using UUIDs to identify the filesystem in /etc/fstab, you can find the UUID for the new filesystem with blkid /dev/sdb1:
```
 # blkid /dev/sdb1
```

Reload systemd and mount the new /boot

On BIOS systems:

 # systemctl daemon-reload
 # mount /boot

On UEFI systems:

 # systemctl daemon-reload
 # mount /boot
 # mount /boot/efi

Only on BIOS systems: install the grub bootloader on the primary device
```
 # grub2-install /dev/sda
```
You may also install the grub bootloader on the new device, in case it gets selected as primary device by the BIOS:
```
 # grub2-install /dev/sdb
```

Rebuild the grub menu

 # grub2-mkconfig -o /etc/grub2$(test -e /sys/firmware/efi && echo "-efi").cfg $(grub2-mkconfig --help | grep -q -- --update-bls-cmdline && echo "--update-bls-cmdline")

[Optional]: RHEL9 and later UEFI systems only : update /boot/efi/EFI/redhat/grub.cfg stub file with new /boot UUID:

 # cat /boot/efi/EFI/redhat/grub.cfg
 search --no-floppy --root-dev-only --fs-uuid --set=dev <UUID OF BOOT PARTITION>
 set prefix=($dev)/grub2
 export $prefix
 configfile $prefix/grub.cfg

Reboot the system and make sure BIOS is pointed to the newly configured boot device.

SBR

Product(s)

Red Hat Enterprise Linux

Components

grub
parted

Category

Migrate

Tags

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