Partition and format linux

10 fdisk Commands to Manage Linux Disk Partitions

fdisk stands (for “fixed disk or format disk“) is an most commonly used command-line based disk manipulation utility for a Linux/Unix systems. With the help of fdisk command you can view, create, resize, delete, change, copy and move partitions on a hard drive using its own user friendly text based menu driven interface.

This tool is very useful in terms of creating space for new partitions, organising space for new drives, re-organising an old drives and copying or moving data to new disks. It allows you to create a maximum of four new primary partition and number of logical (extended) partitions, based on size of the hard disk you have in your system.

fdisk command to manage disk partition

This article explains 10 basic fdisk commands to manage a partition table in Linux based systems. You must be root user to run fdisk command, otherwise you will get a “command not found” error.

1. View all Disk Partitions in Linux

The following basic command list all existing disk partition on your system. The ‘-l‘ argument stand for (listing all partitions) is used with fdisk command to view all available partitions on Linux. The partitions are displayed by their device’s names. For example: /dev/sda, /dev/sdb or /dev/sdc.

2. View Specific Disk Partition in Linux

To view all partitions of specific hard disk use the option ‘-l‘ with device name. For example, the following command will display all disk partitions of device /dev/sda. If you’ve different device names, simple write device name as /dev/sdb or /dev/sdc.

3. Check all Available fdisk Commands

If you would like to view all commands which are available for fdisk. Simply use the following command by mentioning the hard disk name such as /dev/sda as shown below. The following command will give you output similar to below.

Type ‘m‘ to see the list of all available commands of fdisk which can be operated on /dev/sda hard disk. After, I enter ‘m‘ on the screen, you will see the all available options for fdisk that you can be used on the /dev/sda device.

4. Print all Partition Table in Linux

To print all partition table of hard disk, you must be on command mode of specific hard disk say /dev/sda.

From the command mode, enter ‘p‘ instead of ‘m‘ as we did earlier. As I enter ‘p‘, it will print the specific /dev/sda partition table.

5. How to Delete a Partition in Linux

If you would like to delete a specific partition (i.e /dev/sda9) from the specific hard disk such as /dev/sda. You must be in fdisk command mode to do this.

Next, enter ‘d‘ to delete any given partition name from the system. As I enter ‘d‘, it will prompt me to enter partition number that I want to delete from /dev/sda hard disk. Suppose I enter number ‘4‘ here, then it will delete partition number ‘4‘ (i.e. /dev/sda4) disk and shows free space in partition table. Enter ‘w‘ to write table to disk and exit after making new alterations to partition table. The new changes would only take place after next reboot of system. This can be easily understood from the below output.

Warning : Be careful, while performing this step, because using option ‘d‘ will completely delete partition from system and may lost all data in partition.

6. How to Create a New Partition in Linux

If you’ve free space left on one of your device say /dev/sda and would like to create a new partition under it. Then you must be in fdisk command mode of /dev/sda. Type the following command to enter into command mode of specific hard disk.

After entering in command mode, now press “n” command to create a new partition under /dev/sda with specific size. This can be demonstrated with the help of following given output.

While creating a new partition, it will ask you two options ‘extended‘ or ‘primary‘ partition creation. Press ‘e‘ for extended partition and ‘p‘ for primary partition. Then it will ask you to enter following two inputs.

1. First cylinder number of the partition to be create.
2. Last cylinder number of the partition to be created (Last cylinder, +cylinders or +size).

You can enter the size of cylinder by adding “+5000M” in last cylinder. Here, ‘+‘ means addition and 5000M means size of new partition (i.e 5000MB). Please keep in mind that after creating a new partition, you should run ‘w‘ command to alter and save new changes to partition table and finally reboot your system to verify newly created partition.

7. How to Format a Partition in Linux

After the new partition is created, don’t skip to format the newly created partition using ‘mkfs‘ command. Type the following command in the terminal to format a partition. Here /dev/sda4 is my newly created partition.

8. How to Check Size of a Partition in Linux

After formatting new partition, check the size of that partition using flag ‘s‘ (displays size in blocks) with fdisk command. This way you can check size of any specific device.

9. How to Fix Partition Table Order

If you’ve deleted a logical partition and again recreated it, you might notice ‘partition out of order‘ problem or error message like ‘Partition table entries are not in disk order‘.

For example, when three logical partitions such as (sda4, sda5 and sda6) are deleted, and new partition created, you might expect the new partition name would be sda4. But, the system would create it as sda5. This happens because of, after the partition are deleted, sda7 partition had been moved as sda4 and free space shift to the end.

To fix such partition order problems, and assign sda4 to the newly created partition, issue the ‘x‘ to enter an extra functionality section and then enter ‘f‘ expert command to fix the order of partition table as shown below.

After, running ‘f‘ command, don’t forget to run ‘w‘ command to save and exit from fdisk command mode. Once it fixed partition table order, you will no longer get error messages.

10. How to Disable Boot Flag (*) of a Partition

By default, fdisk command shows the boot flag (i.e. ‘*‘) symbol on each partition. If you want to enable or disable boot flag on a specific partition, do the following steps.

Press ‘p‘ command to view the current partition table, you see there is a boot flag (asterisk (*) symbol in orange color) on /dev/sda1 disk as shown below.

Next enter command ‘a‘ to disable boot flag, then enter partition number ‘1‘ as (i.e. /dev/sda1) in my case. This will disable boot flag on the partition /dev/sda1. This will remove the asterisk (*) flag.

I’ve tried my best to include almost all basic commands of fdisk commands, but still fdisk contains a variety of other expert commands you can use them by entering ‘x‘. For more detailed information, check out ‘man fdisk‘ command from the terminal. If I’ve missed any important command, please do share with me via comment section.

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Partitioning

Disk partitioning or disk slicing is the creation of one or more regions on secondary storage, so that each region can be managed separately.

An entire disk may be allocated to a single partition, or multiple ones for cases such as dual-booting, maintaining a swap partition, or to logically separate data such as audio and video files. The partitioning scheme is stored in a partition table such as Master Boot Record (MBR) or GUID Partition Table (GPT).

Partition tables are created and modified using one of many partitioning tools. The tools available for Arch Linux are listed in the #Partitioning tools section.

Partitions usually contain a file system directly which is accomplished by creating a file system on (a.k.a. formatting) the partition. Alternatively, partitions can contain LVM, block device encryption or RAID, which ultimately provide device files on which a file system can be placed (or the devices can be stacked further).

Any block device (e.g. disk, partition, LUKS device, LVM logical volume or RAID array) that directly contains a mountable file system is called a volume.

Contents

Partition table

There are two main types of partition table available. These are described below in the #Master Boot Record (MBR) and #GUID Partition Table (GPT) sections along with a discussion on how to choose between the two. A third, less common alternative is using a partitionless disk, which is also discussed.

Use a partitioning tool to view the partition table of a block device.

Master Boot Record

The Master Boot Record (MBR) is the first 512 bytes of a storage device. It contains an operating system bootloader and the storage device’s partition table. It plays an important role in the boot process under BIOS systems. See Wikipedia:Master boot record#Disk partitioning for the MBR structure.

Master Boot Record (bootstrap code)

The first 440 bytes of MBR are the bootstrap code area. On BIOS systems it usually contains the first stage of the boot loader. The bootstrap code can be backed up, restored from backup or erased using dd.

Master Boot Record (partition table)

In the MBR partition table (also known as DOS or MS-DOS partition table) there are 3 types of partitions:

Primary partitions can be bootable and are limited to four partitions per disk or RAID volume. If the MBR partition table requires more than four partitions, then one of the primary partitions needs to be replaced by an extended partition containing logical partitions within it.

Extended partitions can be thought of as containers for logical partitions. A hard disk can contain no more than one extended partition. The extended partition is also counted as a primary partition so if the disk has an extended partition, only three additional primary partitions are possible (i.e. three primary partitions and one extended partition). The number of logical partitions residing in an extended partition is unlimited. A system that dual boots with Windows will require for Windows to reside in a primary partition.

The customary numbering scheme is to create primary partitions sda1 through sda3 followed by an extended partition sda4. The logical partitions on sda4 are numbered sda5, sda6, etc.

GUID Partition Table

GUID Partition Table (GPT) is a partitioning scheme that is part of the Unified Extensible Firmware Interface specification; it uses globally unique identifiers (GUIDs), or UUIDs in the Linux world, to define partitions and partition types. It is designed to succeed the Master Boot Record partitioning scheme method.

At the start of a GUID Partition Table disk there is a protective Master Boot Record (PMBR) to protect against GPT-unaware software. This protective MBR just like an ordinary MBR has a bootstrap code area which can be used for BIOS/GPT booting with boot loaders that support it.

Choosing between GPT and MBR

GUID Partition Table (GPT) is an alternative, contemporary, partitioning style; it is intended to replace the old Master Boot Record (MBR) system. GPT has several advantages over MBR which has quirks dating back to MS-DOS times. With the recent developments to the formatting tools, it is equally easy to get good dependability and performance for GPT or MBR.

Some points to consider when choosing:

• To dual-boot with Windows (both 32-bit and 64-bit) using Legacy BIOS, the MBR scheme is required.
• To dual-boot Windows 64-bit using UEFI mode instead of BIOS, the GPT scheme is required.
• If you are installing on older hardware, especially on old laptops, consider choosing MBR because its BIOS might not support GPT (but see below how to fix it).
• If you are partitioning a disk that is larger than 2 TiB, you need to use GPT.
• It is recommended to always use GPT for UEFI boot, as some UEFI implementations do not support booting to the MBR while in UEFI mode.
• If none of the above apply, choose freely between GPT and MBR. Since GPT is more modern, it is recommended in this case.

Some advantages of GPT over MBR are:

• Provides a unique disk GUID and unique partition GUID (PARTUUID) for each partition — A good filesystem-independent way of referencing partitions and disks.
• Provides a filesystem-independent partition name (PARTLABEL).
• Arbitrary number of partitions — depends on space allocated for the partition table — No need for extended and logical partitions. By default the GPT table contains space for defining 128 partitions. However if you want to define more partitions, you can allocate more space to the partition table (currently only gdisk is known to support this feature).
• Uses 64-bit LBA for storing Sector numbers — maximum addressable disk size is 2 ZiB. MBR is limited to addressing 2 TiB of space per drive.[1]
• Stores a backup header and partition table at the end of the disk that aids in recovery in case the primary ones are damaged.
• CRC32 checksums to detect errors and corruption of the header and partition table.

The section on #Partitioning tools contains a table indicating which tools are available for creating and modifying GPT and MBR tables.

Partitionless disk

This article or section needs expansion.

Partitionless disk a.k.a. superfloppy refers to a storage device without a partition table, having one file system occupying the whole storage device. The boot sector present on a partitionless device is called a volume boot record (VBR).

Btrfs partitioning

Btrfs can occupy an entire data storage device and replace the MBR or GPT partitioning schemes. See the Btrfs#Partitionless Btrfs disk instructions for details.

Partition scheme

This article or section needs expansion.

There are no strict rules for partitioning a hard drive, although one may follow the general guidance given below. A disk partitioning scheme is determined by various issues such as desired flexibility, speed, security, as well as the limitations imposed by available disk space. It is essentially personal preference. If you would like to dual boot Arch Linux and a Windows operating system please see Dual boot with Windows.

Single root partition

This scheme is the simplest and should be enough for most use cases. A swapfile can be created and easily resized as needed. It usually makes sense to start by considering a single / partition and then separate out others based on specific use cases like RAID, encryption, a shared media partition, etc.

Discrete partitions

This article or section needs expansion.

Separating out a path as a partition allows for the choice of a different filesystem and mount options. In some cases like a media partition, they can also be shared between operating systems.

Below are some example layouts that can be used when partitioning, and the following subsections detail a few of the directories which can be placed on their own separate partition and then mounted at mount points under / . See file-hierarchy(7) for a full description of the contents of these directories.

The root directory is the top of the hierarchy, the point where the primary filesystem is mounted and from which all other filesystems stem. All files and directories appear under the root directory / , even if they are stored on different physical devices. The contents of the root filesystem must be adequate to boot, restore, recover, and/or repair the system. Therefore, certain directories under / are not candidates for separate partitions.

The / partition or root partition is necessary and it is the most important. The other partitions can be replaced by it.

/ traditionally contains the /usr directory, which can grow significantly depending upon how much software is installed. 15–20 GiB should be sufficient for most users with modern hard disks. If you plan to store a swap file here, you might need a larger partition size.

The /boot directory contains the kernel and ramdisk images as well as the boot loader configuration file and boot loader stages. It also stores data that is used before the kernel begins executing user-space programs. /boot is not required for normal system operation, but only during boot and kernel upgrades (when regenerating the initial ramdisk).

A suggested size for /boot is 200 MiB unless you are using EFI system partition as /boot , in which case at least 260 MiB is recommended.

The /home directory contains user-specific configuration files, caches, application data and media files.

Separating out /home allows / to be re-partitioned separately, but note that you can still reinstall Arch with /home untouched even if it is not separate—the other top-level directories just need to be removed, and then pacstrap can be run.

You should not share home directories between users on different distributions, because they use incompatible software versions and patches. Instead, consider sharing a media partition or at least using different home directories on the same /home partition. The size of this partition varies.

The /var directory stores variable data such as spool directories and files, administrative and logging data, pacman’s cache, etc. It is used, for example, for caching and logging, and hence frequently read or written. Keeping it in a separate partition avoids running out of disk space due to flunky logs, etc.

It exists to make it possible to mount /usr as read-only. Everything that historically went into /usr that is written to during system operation (as opposed to installation and software maintenance) must reside under /var .

/var will contain, among other data, the pacman cache. Retaining these packages is helpful in case a package upgrade causes instability, requiring a downgrade to an older, archived package. The pacman cache will grow as the system is expanded and updated, but it can be safely cleared if space becomes an issue. 8–12 GiB on a desktop system should be sufficient for /var , depending on how much software will be installed.

One can consider mounting a «data» partition to cover various files to be shared by all users. Using the /home partition for this purpose is fine as well. The size of this partition varies.

A swap is a file or partition that provides disk space used as virtual memory. Swap files and swap partitions are equally performant, but swap files are much easier to resize as needed. A swap partition can potentially be shared between operating systems, but not if hibernation is used.

Historically, the general rule for swap partition size was to allocate twice the amount of physical RAM. As computers have gained ever larger memory capacities, this rule is outdated. For example, on average desktop machines with up to 512 MiB RAM, the 2× rule is usually adequate; if a sufficient amount of RAM (more than 1024 MiB) is available, it may be possible to have a smaller swap partition.

To use hibernation (a.k.a suspend to disk) it is advised to create the swap partition at the size of RAM. Although the kernel will try to compress the suspend-to-disk image to fit the swap space there is no guarantee it will succeed if the used swap space is significantly smaller than RAM. See Power management/Suspend and hibernate#Hibernation for more information.

Example layouts

This article or section needs expansion.

The following examples use /dev/sda as the example disk with /dev/sda1 as the first partition. The block device naming scheme will differ if you are partitioning a NVMe disk (e.g. /dev/nvme0n1 with partitions starting from /dev/nvme0n1p1 ) or an SD card or eMMC disk (e.g. /dev/mmcblk0 with partitions starting from /dev/mmcblk0p1 ). See Device file#Block device names for more information.

UEFI/GPT layout example

Mount point on the installed system	Partition	Partition type GUID	Partition attributes	Suggested size
/boot or /efi 1	/dev/sda1	C12A7328-F81F-11D2-BA4B-00A0C93EC93B : EFI system partition	At least 260 MiB
[SWAP]	/dev/sda2	0657FD6D-A4AB-43C4-84E5-0933C84B4F4F : Linux swap	More than 512 MiB
/	/dev/sda3	4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709 : Linux x86-64 root (/)	Remainder of the device

BIOS/MBR layout example

Mount point on the installed system	Partition	Partition type ID	Boot flag	Suggested size
[SWAP]	/dev/sda1	82 : Linux swap	No	More than 512 MiB
/	/dev/sda2	83 : Linux	Yes	Remainder of the device
N/A	Unallocated space 2	N/A	N/A	At least 16.5 KiB at the end of the disk

BIOS/GPT layout example

Mount point on the installed system	Partition	Partition type GUID	Partition attributes	Suggested size
None	/dev/sda1	21686148-6449-6E6F-744E-656564454649 : BIOS boot partition 3	1 MiB
[SWAP]	/dev/sda2	0657FD6D-A4AB-43C4-84E5-0933C84B4F4F : Linux swap	More than 512 MiB
/	/dev/sda3	4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709 : Linux x86-64 root (/)	Remainder of the device

1. The ESP can be mounted to /efi if the used boot loader is capable of accessing the file system (and everything above it) on which the kernel and initramfs images are located. See EFI system partition#Typical mount points and the warning in Arch boot process#Boot loader for details.
2. An unpartitioned space of at least 33 512-byte sectors (16.5 KiB) at the end of the disk to allow converting to GPT in the future. The space will be required for the backup GPT header. The recommendation to preserve an unpartitioned space applies to all MBR partitioned disks.
3. A BIOS boot partition is only required when using GRUB for BIOS booting from a GPT disk. The partition has nothing to do with /boot , and it must not be formatted with a file system or mounted.

Tools

Partitioning tools

The following programs are used to create and/or manipulate device partition tables and partitions. See the linked articles for the exact commands to be used.

This table will help you to choose utility for your needs:

MBR	GPT
Dialog	fdisk parted	fdisk gdisk parted
Pseudo-graphics	cfdisk	cfdisk cgdisk
Non-interactive	sfdisk parted	sfdisk sgdisk parted
Graphical	GParted gnome-disk-utility partitionmanager	GParted gnome-disk-utility partitionmanager

fdisk

fdisk and its related utilities are described in the fdisk article.

• fdisk ( util-linux )
  • fdisk(8) – Dialog-driven program for creation and manipulation of partition tables.
  • cfdisk(8) – Curses-based variant of fdisk.
  • sfdisk(8) – Scriptable variant of fdisk.

GPT fdisk

gdisk and its related utilities are described in the gdisk article.

GNU Parted

These group of tools are described in the GNU Parted article.

Backup

• fdisk can create a backup of the partitions table. See fdisk#Backup and restore partition table.
• GPT fdisk can create a binary backup consisting of the protective MBR, the main GPT header, the backup GPT header, and one copy of the partition table. See GPT fdisk#Backup and restore partition table.

Recovery

• gpart — A utility that guesses the contents of a destroyed MBR partition table. Its usage is explained in the gpart(8) man page.

https://github.com/baruch/gpart || gpart

• GPT fdisk — A partitioning tool that can restore the primary GPT header (located at the start of the disk) from the secondary GPT header (located at the end of the disk) or vice versa.

https://www.rodsbooks.com/gdisk/ || gptfdisk

• TestDisk — A utility that supports recovering lost partitions on both MBR and GPT.

https://www.cgsecurity.org/index.html?testdisk.html || testdisk

Partition alignment

fdisk, gdisk and parted handle alignment automatically. See GNU Parted#Check alignment if you want to verify your alignment after partitioning.

For certain drives Advanced Format might be able to provide a better-performing alignment.

GPT kernel support

The CONFIG_EFI_PARTITION option in the kernel config enables GPT support in the kernel (despite the name, EFI PARTITION). This option must be built in the kernel and not compiled as a loadable module. This option is required even if GPT disks are used only for data storage and not for booting. This option is enabled by default in all Arch’s officially supported kernels. In case of a custom kernel, enable this option by doing CONFIG_EFI_PARTITION=y .

Troubleshooting

This article or section needs expansion.

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