Whats is a disk partition
Partitioning divides a disk drive into one or more logical disks. Each partition is treated as a separate disk with its own file system. Partition information is stored in a partition table. There are 2 types of partitions that can be created using the fdisk utility :
- Primary Partitions
- Extended Partitions
Primary Vs extended partitions
– The original partitioning scheme for PC hard disks allowed only four partitions, called primary partitions.
– To create more than four partitions, one of these four partitions can be divided into many smaller partitions, called logical partitions. When a primary partition is subdivided in this way, it is known as an extended partition.
Creating primary partition using fdisk
The fdisk utility is a common partition table manipulator for Linux. Use ‘fdisk –l’ to list the partition table. We will assume you are modifying the first drive on your system.
1. First create a new partition on your drive with the (n) command option:
# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0x96151d76.
Command (m for help): n
2. On the next step either press p or press ENTER which takes up the default value p (primary partition).
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
3. Next you can choose a partition number for your primary partition. By default, it will automatically select the next available partition on the drive if you press ENTER.
Select (default p): p
Partition number (1-4, default 1): 1
4. Determine the starting point for the partition, default will select the next available cylinder on the drive. On the next step select the size of your new partition, for example, to make a 1 GB partition you would set the command as +1024M.
First sector (2048-41943039, default 2048): ### press ENTER here Using default value 2048 Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +1024M Partition 1 of type Linux and of size 1 GiB is set
5. This will then take you back to the command line where you can see your newly created partition. Use the option p to print out the partition table.
Command (m for help): p
Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x96151d76
Device Boot Start End Blocks Id System
/dev/sdb1 2048 2099199 1048576 83 Linux
You can see the newly created partition listed in blocks rather than megabytes and the partition ID type automatically defaults to Linux which will allow you to create your filesystem on that partition.
6. Finally save and exit fdisk with the write/quit command (w). Changes will be permanent after this command is executed.
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
7. Run the partprobe command to scan the newly modified partition table:
# partprobe
If partprobe does not identify the newly modified table then a reboot will be required. You can also run the command “fdisk -l” to verify the new partition.
# fdisk -l Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk label type: dos Disk identifier: 0x96151d76 Device Boot Start End Blocks Id System /dev/sdb1 2048 2099199 1048576 83 Linux
Changing partition ID type
As stated earlier in the post, When you create a new partition, the partition ID type automatically defaults to Linux (83). You also have an option to change the partition type later on.
In order to change partition type you will need to change the ID. This will allow you to change the type between several different options. In this example we are going to change the type ID of /dev/sdb1. Use the option t to change the partition ID type. You can use L option to list out available partition ID types.
# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): p
Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x96151d76
Device Boot Start End Blocks Id System
/dev/sdb1 2048 2099199 1048576 83 Linux
Command (m for help): t Selected partition 1 Hex code (type L to list all codes): L 0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris 1 FAT12 27 Hidden NTFS Win 82 Linux swap / So c1 DRDOS/sec (FAT- 2 XENIX root 39 Plan 9 83 Linux c4 DRDOS/sec (FAT- 3 XENIX usr 3c PartitionMagic 84 OS/2 hidden C: c6 DRDOS/sec (FAT- 4 FAT16 <32M 40 Venix 80286 85 Linux extended c7 Syrinx 5 Extended 41 PPC PReP Boot 86 NTFS volume set da Non-FS data 6 FAT16 42 SFS 87 NTFS volume set db CP/M / CTOS / . 7 HPFS/NTFS/exFAT 4d QNX4.x 88 Linux plaintext de Dell Utility 8 AIX 4e QNX4.x 2nd part 8e Linux LVM df BootIt 9 AIX bootable 4f QNX4.x 3rd part 93 Amoeba e1 DOS access a OS/2 Boot Manag 50 OnTrack DM 94 Amoeba BBT e3 DOS R/O b W95 FAT32 51 OnTrack DM6 Aux 9f BSD/OS e4 SpeedStor c W95 FAT32 (LBA) 52 CP/M a0 IBM Thinkpad hi eb BeOS fs e W95 FAT16 (LBA) 53 OnTrack DM6 Aux a5 FreeBSD ee GPT f W95 Ext'd (LBA) 54 OnTrackDM6 a6 OpenBSD ef EFI (FAT-12/16/ 10 OPUS 55 EZ-Drive a7 NeXTSTEP f0 Linux/PA-RISC b 11 Hidden FAT12 56 Golden Bow a8 Darwin UFS f1 SpeedStor 12 Compaq diagnost 5c Priam Edisk a9 NetBSD f4 SpeedStor 14 Hidden FAT16 <3 61 SpeedStor ab Darwin boot f2 DOS secondary 16 Hidden FAT16 63 GNU HURD or Sys af HFS / HFS+ fb VMware VMFS 17 Hidden HPFS/NTF 64 Novell Netware b7 BSDI fs fc VMware VMKCORE 18 AST SmartSleep 65 Novell Netware b8 BSDI swap fd Linux raid auto 1b Hidden W95 FAT3 70 DiskSecure Mult bb Boot Wizard hid fe LANstep 1c Hidden W95 FAT3 75 PC/IX be Solaris boot ff BBT 1e Hidden W95 FAT1 80 Old Minix Hex code (type L to list all codes): 8e Changed type of partition 'Linux' to 'Linux LVM'
Finally, save and exit fdisk with the write/quit command (w). Note: Changes will be permanent after this command is executed.
Command (m for help): w