On Linux distributions, fdisk is the best tool to manage disk partitions. fdisk is a text based utility.
Using fdisk you can create a new partition, delete an existing partition, or change existing partition.
Using fidsk you are allowed to create a maximum of four primary partition, and any number of logical partitions, based on the size of the disk.
Keep in mind that any single partition requires a minimum size of 40MB.
In this article, let us review how to use fdisk command using practical examples.
Warning: Don’t delete, modify, or add partition, if you don’t know what you are doing. You will lose your data!
1. View All Existing Disk Partitions Using fdisk -l
Before you create a new partition, or modify an existing partition, you might want to view all available partition in the system.
Use fdisk -l to view all available partitions as shown below.
# fdisk -l Disk /dev/sda: 80.0 GB, 80026361856 bytes 255 heads, 63 sectors/track, 9729 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk 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 partitions from all the connected hard disks. When you have more than one disk on the system, the partitions list are ordered by the device’s /dev name. For example, /dev/sda, /dev/sdb, /dev/sdc and so on.
2. View Partitions of a Specific Hard Disk using fdisk -l /dev/sd{a}
To view all partitions 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): m Command 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 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 Partition Using fdisk Command d
Let us assume that you like to combine several partitions (for example, /dev/sda6, /dev/sda7 and /dev/sda8) into a single disk partition. To do this, you should first delete all those individual partitions, 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): p Disk /dev/sda: 80.0 GB, 80026361856 bytes 255 heads, 63 sectors/track, 9729 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk 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 Command (m for help): d Partition number (1-9): 8 Command (m for help): d Partition number (1-8): 7 Command (m for help): d Partition number (1-7): 6 Command (m for help): w The 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 the next reboot or after you run partprobe(8) or kpartx(8) Syncing disks.
4. Create a New Disk Partition with Specific Size Using fdisk Command n
Once you’ve deleted all the existing partitions, you can create a new partition using all available space 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): n
First cylinder (2662-5283, default 2662):
Using default value 2662
Last 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 partition with the specific size. While creating a new partition, it expects following two inputs.
- Starting cylinder number of the partition to be create (First cylinder).
- Size of the partition (or) the last cylinder number (Last cylinder, +cylinders or +size ).
Please keep in mind that you should issue the fdisk write command (w) after any modifications.
Command (m for help): w The 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 the next reboot or after you run partprobe(8) or kpartx(8) Syncing disks.
After the partition is created, format it using the mkfs command as shown below.
# mkfs.ext3 /dev/sda7
5. View the Size of an existing Partition Using fdisk -s
As shown below, fdisk -s displays the size of the partition in blocks.
# fdisk -s /dev/sda7 4843566
The above output corresponds to about 4900MB.
6. Toggle the Boot Flag of a Partition Using fdisk Command a
Fdisk command displays the boot flag of each partition. When you want to disable or enable the boot flag on the corresponding partition, do the following.
If you don’t know why are you are doing this, you’ll mess-up your system.
# 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): p Disk /dev/sda: 80.0 GB, 80026361856 bytes 255 heads, 63 sectors/track, 9729 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk 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 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): a Partition number (1-7): 5 Command (m for help): p Disk /dev/sda: 80.0 GB, 80026361856 bytes 255 heads, 63 sectors/track, 9729 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk 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 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):
As seen above, the boot flag is disabled on the partition /dev/sda5.
7. Fix Partition Table Order Using fdisk Expert Command f
When you delete a logical partition, and recreate it again, you might see the “partition out of order” issue. i.e “Partition table entries are not in disk order” error message.
For example, when you delete three logical partitions (sda6, sda7 and sda8), and create a new partition, you might expect the new partition name to be sda6. But, the system might’ve created the new partition as sda7. This is because, after the partitions are deleted, sda9 partition has been moved as sda6 and the free space is moved to the end.
To fix this partition order issue, and assign sda6 to the newly created partition, execute the expert command f 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): p Disk /dev/sda: 80.0 GB, 80026361856 bytes 255 heads, 63 sectors/track, 9729 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk 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 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): x Expert command (m for help): f Done. Expert command (m for help): w The 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 the next reboot or after you run partprobe(8) or kpartx(8) Syncing disks.
Once the partition table order is fixed, you’ll not get the “Partition table entries are not in disk order” error message anymore.
# fdisk -l Disk /dev/sda: 80.0 GB, 80026361856 bytes 255 heads, 63 sectors/track, 9729 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk 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 3264 4843566 83 Linux /dev/sda7 3265 5283 16217586 b W95 FAT32
My name is Ramesh Natarajan. I will be posting instruction guides, how-to, troubleshooting tips and tricks on Linux, database, hardware, security and web. My focus is to write articles that will either teach you or help you resolve a problem. Read more about
Comments on this entry are closed.
thanxs ……
sir , you provides very good tuts….i use to save every single page of your articles… thanxs again..
The “Warning Message” in this article 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/sda4
But 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 options, only then the command 🙂
Conclusion:
No Playing with linux, at times it is merciless
s/loose/lose/
Thanks for tip number 7.
@Chris,
Thanks for pointing out the typo. It’s fixed.
thank u sir,its very useful
good tips.
how to add new space on the existing partition using fdisk without losing data?
Add new space w/o loosing data with fdisk….? i think that’s not posible.
@raralee
resizing a partition without losing data is not possible.
But if you have a plan already that you would be changing partition sizes, then please use LVM ( Logical Volume Manager )
I have problem with fdisk command
when i tell it to make 80 megabyte drive with this input (( +80M)) it make 85 megabyte drive and the drive is made by vmware player on ubutnu 10.04
any idea why this happen ?
Thanks a lot!
After restoring a Windows installation to a new harddisk, i found that i had made a mistake with the partition-order, causing a non-boot. After reordering the partitions, it boots again (although i won’t use it, not my machine ;).
It will be better if you add how to change the partition type too in this.
Change the partition type on the newly created partition from Linux to LVM (8e).
# fdisk /dev/sda
Command (m for help): t
Partition number (1-4): 4
Hex code (type L to list codes): 8e
Changed system type of partition 4 to 8e (Unknown)
Command (m for help): w
i had grub15 error so i read that using fdisk will adjust order of sda. so i did fdisk -l then fdisk /dev/sda then x f showed only two partitions and did w. now i am having problem that my home is not loading system in root emergency mode. i can see my data after using ctrl D and then home and then my data but i cant backup or copy my data to a usb drive plz tell what to do after doing fdisk -l i can see all partitions i.e. 6 partiions
can any one give me the codings for GPIO testing in ITBOK for the omap 3 EVM,
Also give me the Uboot commands for the GPIO testing
Regards
Arun
I am getting error using command partporbe. after reboot only it will working
Ramesh,
Article was really good!!!
Just want to check few queries related to re sizing existing partition in USB drive.
I have installed the Ubuntu 14.0.1 on my USB drive and allocated 4 GB out of 16GB USB drive.
I have trying to re size the 4GB to 10 GB using gparted but again showing 4GB as used and 6 GB as unused.
How do I make 10 GB allocated to primary?
In the command you gave:
‘fdisk -s /dev/sda7’
‘4843566’
If the deprecated -s option displays partition size in number of 512 byte blocks, I think this should be about 2480MB, not 4900MB. I may be mistaken, and a minor nit-pick I know…