Change linux partition type

How can I check and change the partition table type?

New computers that ship with Windows 8 also come with a different partition table than before. This along with the move to UEFI causes confusion, as users are unaware of the newer partition table and are trying to install operating systems in legacy style on these computers and vice versa. (Non-UEFI installs can be done but need a special partition. UEFI installs on MBR partitioned disks also seem to be possible.)

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What is a partition table? How is it related to Windows 8?

In addition to general partitioning, it should be noted that information about partitions are stored in a partition table on the hard disk.

The whole topic didn’t receive much attention because DOS/Windows computers – where one would install Linux onto – just had one choice for almost three decades. (MBR was introduced in 1983.) Until Windows 8 finally replaced the long overdue and outdated BIOS/MBR subsystem combination with UEFI/GPT. (Comparison of GPT and MBR on the Arch Wiki.)

While GPT is the name for the new format, there is some confusion about how to name the old one as MBR previously described the bootloader code that is stored along the partition information in the partition table.

How do I check and change the partition table?

Read these instructions carefully before you start!

1. GUI-method — Using GParted To find out what partition table type the selected drive has select View >Device Information from the menu. Select the disk of which you want to change the partition, then select Device >Create Partition Table from the menu. If you get a warning that the device contains active partitions, unmount these. Note that you cannot unmount partitions of your currently running operating system. You will then see the window below, where you can choose the partition table type. msdos is what GParted calls the old format, gpt the newer one. All the others for other operating systems or architectures. Please also note the warning message. Creating a new partition table will discard all information about existing partitions on the disk. It will not overwrite data on the partitions, but you still don’t want to have to dig through and restore data afterwards. Therefore consider the old partitions gone and all data lost after you created the new partition table and backup your data before doing so.
2. CLI-method — Using parted To display partition table information run:

# This is a destructive action that will destroy all data on the partitions of the device sudo parted device mklabel label-type 

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Use fdisk Format Partition

For managing disk partitions, fdisk is a command-line partition editor. It can create, edit, delete, and format almost any partition. It supports all the major partition tables, including GPT, MBR, Sun, SGI, and BSD. It makes fdisk compatible with almost all the standard partition formats.

In this guide, check out how to use fdisk to format a partition.

Format partition using fdisk

The fdisk tool will come pre-installed on almost all the Linux distros. This guide will demonstrate the usage of fdisk on an Ubuntu system.

To confirm that fdisk exists in the system, launch a terminal, and run the following commands.

An interesting feature fdisk offers the interactive mode. It offers far more control and safety over the partition formatting operation. That’s why this will be the primary method demonstrated in this guide.

Using fdisk to format partition

Listing disks

For the interactive mode, fdisk requires the device label in the system. In the case of the Linux filesystem, devices are labeled as “/dev/sd*” or “/dev/hd*” where the asterisk (*) is replaced by an alphabet.

For example, a device labeled as “/dev/sda” will have partitions labeled as “/dev/sda1”, “/dev/sda5” etc.

To list all the disks and their respective partitions, run the following command.

The fdisk tool can also list disks and partitions with a more in-depth report.

To check the partitions of a specific disk, use the following structure.

Launching fdisk interactive mode

Now that we’ve determined the target device, label launch fdisk in the interactive mode.

Any changes made will remain in the memory only. It offers protection from unwanted actions.

To print all the available options, enter “m”.

Creating a partition

It’s an optional step and only applicable if there’s free unpartitioned space on the disk. To verify if there’s any, enter “F”.

To create a partition, enter “n”.

It’s recommended to use the default value for the first sector of the new partition.

The last sector will determine the amount of space the new partition will take. In this step, fdisk accepts various formats of values. For example, if the partition size is to be 2GB, then enter “+2G”. If no unit is specified, then fdisk will use sectors as the unit.

If there were any previous partition in the location, fdisk would prompt the warning that it contains a previous filesystem signature. It’s recommended to remove the signature. Enter “Y” to confirm the action.

Issuing the write command will mark the changes permanent.

Changing partition type

Any partition will have a value assigned for a certain kind of file system. There are various partition types available, for example, FAT12, AIX, SFS, OPUS, BSD/OS, OpenBSD, Linux, etc.

To change the partition type, enter “t”.

Fdisk will ask for the target partition number. If the partition is “/dev/sdb1”, then the partition number is “1”.

In the case of Linux, there’s a big set of supported partition types. To print all the available options, enter “L”. Each partition type has a unique hex code. For this example, we’ll be using “Linux” (hex value 83).

Writing the changes

Assuming everything was configured properly, it’s safe to make the changes permanent. If there’s any issue or you want to discard the current configuration, enter “q”. Fdisk will discard all the changes without writing them to the disk and exit.

Assuming everything was configured properly, enter “w” to write all the changes.

Formatting the partition

There are multiple reasons you may want to format a partition.

• For a new partition, formatting it will make the available storage usable by the operating system.
• If the partition contained any previous data, the formatting would erase the data.
• If a partition is corrupted, then formatting is the way to make it usable again. Of course, the data on the partition will be lost.
• If the partition contains a filesystem that’s not accessible by the operating system, formatting it with a suitable filesystem will allow the operating system access to the storage.

Note that if the partition is mounted, then it’s not possible to perform actions like partition formatting. Unmount the partition using the umount command.

Assuming we have the target partition label, let’s get into formatting it. Unfortunately, the fdisk itself doesn’t incorporate any partition formatting functions. We’ll have to use the mkfs tool for this purpose.

The mkfs tool supports multiple filesystems. For each supported filesystem, mkfs has a different command tool. To list all the supported filesystems and their respective command tools, run the following command.

It’s easy to understand which tool is for what filesystem. For example, “mkfs.ext4” will create an ext4 filesystem on the target partition.

To format the partition in the ext4 format, run the following command.

If there’s already a pre-existing filesystem, mkfs will prompt a warning message. Enter “y” to confirm the action.

Voila! The partition is formatted successfully!

Using the partition

To use a partition, it has to be mounted. Linux comes with a dedicated tool for mounting partitions and disk files. Learn how to mount using the mount command.

In short, mounting a partition requires a mount point where the partition is attached to the operating system. Create a mount point.

To mount the partition on the mount point, run the following command.

Voila! The partition now should be accessible from the mount point.

Final thoughts

Formatting a partition is a simple yet important task. For the command-line interface, fdisk is a great solution.

Not a fan of fdisk? Worry not. There are numerous tools available to manage partitions on Linux. Learn how to format disk partitions.

About the author

Sidratul Muntaha

Student of CSE. I love Linux and playing with tech and gadgets. I use both Ubuntu and Linux Mint.

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