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 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