How to create a new partition using fdisk unix commands in linux and unix.

MANAGING PARTITIONS

What is partition?

Partitioning is a means to divide a single hard drive into many logical drives. A partition is a contiguous set of block on a drive that are treated as an independent disk. A partition table is an index that relates sections of the hard drive to partitions.

This tutorial shows you how to actually partition your hard drive with the fdisk utility. Linux allows only 4 primary partitions. You can have a much larger number of logical partitions by sub-dividing one of the primary partitions. Only one of the primary partitions can be sub-divided.

Examples:

• Four primary partitions
• Mixed primary and logical partitions

The fdisk command is a text-based utility for viewing and managing hard disk partitions on Linux. It’s one of the most powerful tools you can use to manage partitions, but it’s confusing to new users.

This tutorial about the basics of using fdisk to manage a partition table.

List Partitions

The fdisk -l or parted -l commands lists the partitions on your system.

[root@rahul /]# fdisk -l Disk /dev/sda: 17.2 GB, 17179869184 bytes 255 heads, 63 sectors/track, 2088 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000efa3d    Device Boot      Start         End      Blocks   Id  System /dev/sda1   *           1          26      204800   83  Linux Partition 1 does not end on cylinder boundary. /dev/sda2              26        1301    10240000   83  Linux /dev/sda3            1301        1562     2097152   82  Linux swap / Solaris /dev/sda4            1562        2088     4228884    5  Extended /dev/sda5            1562        1626      517837+  82  Linux swap / Solaris /dev/sda6            1627        1691      522081   8e  Linux LVM /dev/sda7            1692        1756      522081   8e  Linux LVM /dev/sda8            1757        1821      522081   83  Linux [root@rahul /]#

You can add a disk’s device name to list only partitions on it. For example, use the following command to only list partitions on the first disk device:

# fdisk -l /dev/sda

Partition Administration using fdisk:

To work on a disk’s partitions, you have to enter command mode. You’ll need the device name of a disk from the fdisk -l command. The following command enters command mode for the first disk device:

#  fdisk /dev/sda

[root@rahul /]# fdisk /dev/sda WARNING: DOS-compatible mode is deprecated. It's strongly recommended to          switch off the mode (command 'c') and change display units to          sectors (command 'u'). Command (m for help):

Using fdisk Command Mode

In command mode, you use single-letter commands to specify actions you want to take. Use m to list out various options that can be used in 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) Command (m for help):

View  the Partition Table

Use p to print the current partition table to the terminal from within command mode.

Command (m for help): p Disk /dev/sda: 17.2 GB, 17179869184 bytes 255 heads, 63 sectors/track, 2088 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000efa3d    Device Boot      Start         End      Blocks   Id  System /dev/sda1   *           1          26      204800   83  Linux Partition 1 does not end on cylinder boundary. /dev/sda2              26        1301    10240000   83  Linux /dev/sda3            1301        1562     2097152   82  Linux swap / Solaris /dev/sda4            1562        2088     4228884    5  Extended /dev/sda5            1562        1626      517837+  82  Linux swap / Solaris /dev/sda6            1627        1691      522081   8e  Linux LVM /dev/sda7            1692        1756      522081   8e  Linux LVM /dev/sda8            1757        1821      522081   83  Linux Command (m for help):

Creating a new partition

#fdisk /dev/sda

Use p to list out the partition table information first and

Use n to create a new partition

Command (m for help): n First cylinder (1757-2088, default 1757): Using default value 1757 Last cylinder, +cylinders or +size{K,M,G} (1757-2088, default 2088): +500M Command (m for help): p Disk /dev/sda: 17.2 GB, 17179869184 bytes 255 heads, 63 sectors/track, 2088 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000efa3d    Device Boot      Start         End      Blocks   Id  System /dev/sda1   *           1          26      204800   83  Linux Partition 1 does not end on cylinder boundary. /dev/sda2              26        1301    10240000   83  Linux /dev/sda3            1301        1562     2097152   82  Linux swap / Solaris /dev/sda4            1562        2088     4228884    5  Extended /dev/sda5            1562        1626      517837+  82  Linux swap / Solaris /dev/sda6            1627        1691      522081   8e  Linux LVM /dev/sda7            1692        1756      522081   8e  Linux LVM /dev/sda8            1757        1821      522081   83  Linux Command (m for help):

Next, specify the sector of the disk you want the partition to start at. Press Enter to accept the default sector, which is the first free sector on the disk.

At Last, specify the last sector of the partition on the disk. If you want to use up all available space after the initial sector, just press Enter. You can also specify a specific size, such as +5G for a five gigabyte partition or +512M for a 512 megabyte partition. If you don’t specify a unit after the + sign, fdisk uses sectors as the unit. For example, +10000 results in the end of the partition being 10000 sectors after its beginning.

How to delete partition ?

Use the d command to delete a partition. You’ll be asked for the number of the partition you want to delete, which you can get from the p command. For example, if I wanted to delete the partition at /dev/sda8, I’d type 8.

Command (m for help): d Partition number (1-8): 8 Command (m for help): p Disk /dev/sda: 17.2 GB, 17179869184 bytes 255 heads, 63 sectors/track, 2088 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000efa3d    Device Boot      Start         End      Blocks   Id  System /dev/sda1   *           1          26      204800   83  Linux Partition 1 does not end on cylinder boundary. /dev/sda2              26        1301    10240000   83  Linux /dev/sda3            1301        1562     2097152   82  Linux swap / Solaris /dev/sda4            1562        2088     4228884    5  Extended /dev/sda5            1562        1626      517837+  82  Linux swap / Solaris /dev/sda6            1627        1691      522081   8e  Linux LVM /dev/sda7            1692        1756      522081   8e  Linux LVM Command (m for help):

Saving the partition changes

• Use w to write the changes you’ve made to disk.
• Use q if you want to quit without saving changes.

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. [root@rahul /]#

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