7 linux fdisk command examples to manage hard disk partition

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7 Linux fdisk Command Examples to Manage Hard Disk Par;;onby Balakrishnan Mariyappan on September 14, 2010

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On Linux distribuFons, fdisk is the best tool to manage disk parFFons. fdisk is atext based uFlity.

Using fdisk you can create a new parFFon, delete an exisFng parFFon, or change exisFng parFFon.

Using fidsk you are allowed to create a maximum of four primary parFFon, and any number of logical parFFons, based on the size of thedisk.

7 Linux fdisk Command Examples to Manage Hard Disk ParFFon hPp://www.thegeekstuff.com/2010/09/linux-‐fdisk/

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Keep in mind that any single parFFon requires a minimum size of 40MB.

In this arFcle, let us review how to use fdisk command using pracFcal examples.

Warning: Don’t delete, modify, or add parFFon, if you don’t know what you are doing. You will lose your data!

1. View All Exis;ng Disk Par;;ons Using fdisk -‐l

Before you create a new parFFon, or modify an exisFng parFFon, you might want to view all available parFFon in the system.

Use fdisk -‐l to view all available parFFons as shown below.

# fdisk -l

Disk /dev/sda: 80.0 GB, 80026361856 bytes255 heads, 63 sectors/track, 9729 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesDisk identifier: 0xf6edf6ed

Device Boot Start End Blocks Id System/dev/sda1 1 1959 15735636 c W95 FAT32 (LBA)/dev/sda2 1960 5283 26700030 f W95 Ext'd (LBA)/dev/sda3 5284 6528 10000462+ 7 HPFS/NTFS/dev/sda4 6529 9729 25712032+ c W95 FAT32 (LBA)/dev/sda5 * 1960 2661 5638752 83 Linux/dev/sda6 2662 2904 1951866 83 Linux/dev/sda7 2905 3147 1951866 83 Linux/dev/sda8 3148 3264 939771 82 Linux swap / Solaris/dev/sda9 3265 5283 16217586 b W95 FAT32

The above will list parFFons from all the connected hard disks. When you have more than one disk on the system, the parFFons list areordered by the device’s /dev name. For example, /dev/sda, /dev/sdb, /dev/sdc and so on.

2. View Par;;ons of a Specific Hard Disk using fdisk -‐l /dev/sd{a}

To view all parFFons of the /dev/sda hard disk, do the following.

# fdisk -l /dev/sda

View all fdisk Commands Using fdisk Command m

Use fdisk command m, to view all available fdisk commands as shown below.

# fdisk /dev/sda

The number of cylinders for this disk is set to 9729.There is nothing wrong with that, but this is larger than 1024,and could in certain setups cause problems with:1) software that runs at boot time (e.g., old versions of LILO)2) booting and partitioning software from other OSs (e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): mCommand action a toggle a bootable flag b edit bsd disklabel c toggle the dos compatibility flag d delete a partition l list known partition types


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m print this menu n add a new partition o create a new empty DOS partition table p print the partition table q quit without saving changes s create a new empty Sun disklabel t change a partition's system id u change display/entry units v verify the partition table w write table to disk and exit x extra functionality (experts only)

3. Delete a Hard Disk Par;;on Using fdisk Command d

Let us assume that you like to combine several parFFons (for example, /dev/sda6, /dev/sda7 and /dev/sda8) into a single disk parFFon.To do this, you should first delete all those individual parFFons, as shown below.

# fdisk /dev/sda


Command (m for help): p


Device Boot Start End Blocks Id System/dev/sda1 1 1959 15735636 c W95 FAT32 (LBA)/dev/sda2 1960 5283 26700030 f W95 Ext'd (LBA)/dev/sda3 5284 6528 10000462+ 7 HPFS/NTFS/dev/sda4 6529 9729 25712032+ c W95 FAT32 (LBA)/dev/sda5 * 1960 2661 5638752 83 Linux/dev/sda6 2662 2904 1951866 83 Linux/dev/sda7 2905 3147 1951866 83 Linux/dev/sda8 3148 3264 939771 82 Linux swap / Solaris/dev/sda9 3265 5283 16217586 b W95 FAT32

Command (m for help): dPartition number (1-9): 8



Command (m for help): wThe partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.The kernel still uses the old table. The new table will be used at


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the next reboot or after you run partprobe(8) or kpartx(8)Syncing disks.

4. Create a New Disk Par;;on with Specific Size Using fdisk Command n

Once you’ve deleted all the exisFng parFFons, you can create a new parFFon using all available space as shown below.

# fdisk /dev/sda


Command (m for help): nFirst cylinder (2662-5283, default 2662):Using default value 2662Last cylinder, +cylinders or +size{K,M,G} (2662-3264, default 3264):Using default value 3264

In the above example, fdisk n command is used to create new parFFon with the specific size. While creaFng a new parFFon, it expectsfollowing two inputs.

StarFng cylinder number of the parFFon to be create (First cylinder).Size of the parFFon (or) the last cylinder number (Last cylinder, +cylinders or +size ).

Please keep in mind that you should issue the fdisk write command (w) ader any modificaFons.

Command (m for help): wThe partition table has been altered!


WARNING: Re-reading the partition table failed with error 16: Device or resource busy.The kernel still uses the old table. The new table will be used atthe next reboot or after you run partprobe(8) or kpartx(8)Syncing disks.

Ader the parFFon is created, format it using the mkfs command as shown below.

# mkfs.ext3 /dev/sda7

5. View the Size of an exis;ng Par;;on Using fdisk -‐s

As shown below, fdisk -‐s displays the size of the parFFon in blocks.

# fdisk -s /dev/sda74843566

The above output corresponds to about 4900MB.

6. Toggle the Boot Flag of a Par;;on Using fdisk Command a

Fdisk command displays the boot flag of each parFFon. When you want to disable or enable the boot flag on the correspondingparFFon, do the following.

If you don’t know why are you are doing this, you’ll mess-‐up your system.


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# fdisk /dev/sda




Device Boot Start End Blocks Id System/dev/sda1 1 1959 15735636 c W95 FAT32 (LBA)/dev/sda2 1960 5283 26700030 f W95 Ext'd (LBA)/dev/sda3 5284 6528 10000462+ 7 HPFS/NTFS/dev/sda4 6529 9729 25712032+ c W95 FAT32 (LBA)/dev/sda5 * 1960 2661 5638752 83 Linux/dev/sda6 3265 5283 16217586 b W95 FAT32/dev/sda7 2662 3264 4843566 83 Linux

Partition table entries are not in disk order

Command (m for help): aPartition number (1-7): 5



Device Boot Start End Blocks Id System/dev/sda1 1 1959 15735636 c W95 FAT32 (LBA)/dev/sda2 1960 5283 26700030 f W95 Ext'd (LBA)/dev/sda3 5284 6528 10000462+ 7 HPFS/NTFS/dev/sda4 6529 9729 25712032+ c W95 FAT32 (LBA)/dev/sda5 1960 2661 5638752 83 Linux/dev/sda6 3265 5283 16217586 b W95 FAT32/dev/sda7 2662 3264 4843566 83 Linux


Command (m for help):

As seen above, the boot flag is disabled on the parFFon /dev/sda5.

7. Fix Par;;on Table Order Using fdisk Expert Command f

When you delete a logical parFFon, and recreate it again, you might see the “parFFon out of order” issue. i.e “ParFFon table entries arenot in disk order” error message.

For example, when you delete three logical parFFons (sda6, sda7 and sda8), and create a new parFFon, you might expect the newparFFon name to be sda6. But, the system might’ve created the new parFFon as sda7. This is because, ader the parFFons are deleted,sda9 parFFon has been moved as sda6 and the free space is moved to the end.


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To fix this parFFon order issue, and assign sda6 to the newly created parFFon, execute the expert command f as shown below.

$ fdisk /dev/sda




Device Boot Start End Blocks Id System/dev/sda1 1 1959 15735636 c W95 FAT32 (LBA)/dev/sda2 1960 5283 26700030 f W95 Ext'd (LBA)/dev/sda3 5284 6528 10000462+ 7 HPFS/NTFS/dev/sda4 6529 9729 25712032+ c W95 FAT32 (LBA)/dev/sda5 * 1960 2661 5638752 83 Linux/dev/sda6 3265 5283 16217586 b W95 FAT32/dev/sda7 2662 3264 4843566 83 Linux


Command (m for help): x

Expert command (m for help): fDone.

Expert command (m for help): wThe partition table has been altered!


WARNING: Re-reading the partition table failed with error 16: Device or resource busy.The kernel still uses the old table. The new table will be used atthe next reboot or after you run partprobe(8) or kpartx(8)Syncing disks.

Once the parFFon table order is fixed, you’ll not get the “ParFFon table entries are not in disk order” error message anymore.

# fdisk -l


Device Boot Start End Blocks Id System/dev/sda1 1 1959 15735636 c W95 FAT32 (LBA)/dev/sda2 1960 5283 26700030 f W95 Ext'd (LBA)/dev/sda3 5284 6528 10000462+ 7 HPFS/NTFS/dev/sda4 6529 9729 25712032+ c W95 FAT32 (LBA)/dev/sda5 * 1960 2661 5638752 83 Linux/dev/sda6 2662 3264 4843566 83 Linux/dev/sda7 3265 5283 16217586 b W95 FAT32


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{ 12 comments… read them below or add one }

1 anurag rana September 14, 2010 at 2:50 am

thanxs ……

2 anurag rana September 14, 2010 at 2:52 am

sir , you provides very good tuts….i use to save every single page of your arFcles… thanxs again..

3 Madharasan September 14, 2010 at 4:57 am

The “Warning Message” in this arFcle reminds me of the mistake I did while teaching linux to a group of students.

I was about to enter the command # mkfs.ext3 /dev/sda4But unfortunately just when I have finished typing # mkfs.ext3 /dev/sda , I accidentely pressed the enter key….

There ends the story of my LINUX OS of that machine and my session on Disk management.

Now a days, I first enter the device details and opFons, only then the command

Conclusion:No Playing with linux, at Fmes it is merciless

4 Chris F.A. Johnson September 14, 2010 at 1:43 pm

s/loose/lose/


7 of 11 18 Apr 12 7:29 pm

5 DarkForce September 14, 2010 at 5:21 pm

Thanks for Fp number 7.

6 Ramesh Natarajan September 14, 2010 at 8:51 pm

@Chris,

Thanks for poinFng out the typo. It’s fixed.

7 jameslee September 15, 2010 at 9:35 am

thank u sir,its very useful

8 raralee September 15, 2010 at 11:07 am

good Fps.how to add new space on the exisFng parFFon using fdisk without losing data?

9 Sebas September 16, 2010 at 12:46 pm

Add new space w/o loosing data with fdisk….? i think that’s not posible.

10 madharasan September 17, 2010 at 1:48 am

@raralee

resizing a parFFon without losing data is not possible.But if you have a plan already that you would be changing parFFon sizes, then please use LVM ( Logical Volume Manager )

11 alieblice June 27, 2011 at 3:50 pm

I have problem with fdisk commandwhen i tell it to make 80 megabyte drive with this input (( +80M)) it make 85 megabyte drive and the drive is made by vmwareplayer on ubutnu 10.04

any idea why this happen ?

12 Guus August 29, 2011 at 10:56 am

Thanks a lot!Ader restoring a Windows installaFon to a new harddisk, i found that i had made a mistake with the parFFon-‐order, causing a

non-‐boot. Ader reordering the parFFons, it boots again (although i won’t use it, not my machine .

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7 linux fdisk command examples to manage hard disk partition