Hard Disk Format Command/delete a partition with fdisk / View Hard Drive Partitions with fdisk and parted commands

Linux Hard Disk Format Command

Q. I've installed a new 250GB SATA hard disk on our office CentOS Linux server. How do I format a hard disk under Linux operating system from a shell prompt?
A.. There are total 4 steps involved for hard disk upgrade and installation procedure:
Step #1 : Partition the new disk using fdisk command
Following command will list all detected hard disks:
# fdisk -l | grep '^DOutput:

Disk /dev/sda: 251.0 GB, 251000193024 bytes Disk /dev/sdb: 251.0 GB, 251000193024 bytes

A device name refers to the entire hard disk. For more information see Linux partition naming convention and IDE drive mappings.
To partition the disk - /dev/sdb, enter:
# fdisk /dev/sdbThe basic fdisk commands you need are:

• m - print help
• p - print the partition table
• n - create a new partition
• d - delete a partition
• q - quit without saving changes
• w - write the new partition table and exit

Step#2 : Format the new disk using mkfs.ext3 command

To format Linux partitions using ext2fs on the new disk:
# mkfs.ext3 /dev/sdb1

Step#3 : Mount the new disk using mount command

First create a mount point /disk1 and use mount command to mount /dev/sdb1, enter:
# mkdir /disk1
# mount /dev/sdb1 /disk1
# df -H

Step#4 : Update /etc/fstab file

Open /etc/fstab file, enter:
# vi /etc/fstab
Append as follows:

/dev/sdb1 /disk1 ext3 defaults 1 2

Save and close the file.

Task: Label the partition

You can label the partition using e2label. For example, if you want to label the new partition /backup, enter
# e2label /dev/sdb1 /backup
You can use label name insted of partition name to mount disk using /etc/fstab:
LABEL=/backup /disk1 ext3 defaults 1 2

Linux: How to delete a partition with fdisk command

Q. My system comes with pre installed Linux and XP. Now I would like to delete a partition. How do I delete a partition?

A. Hard disks can be divided into one or more logical disks called partitions. This division is described in the partition table found in sector 0 of the disk.

You need to use fdisk command. It is a menu driven program for creation and manipulation of partition tables. However this program needs the device name (hard disk name) to manipulate partitions. Usually you use following names
/dev/hda
/dev/hdb
/dev/sda
/dev/sdb

So,
=> /dev/hd[a-h] for IDE disks
=> /dev/sd[a-p] for SCSI disks
=> /dev/ed[a-d] for ESDI disks
=> /dev/xd[ab] for XT disks.

A device name refers to the entire hard disk. For more information see Linux partition naming convention and IDE drive mappings.

Before typing any one of the following command(s) make sure you have the backup of important data.

First, get a listing of your current partition scheme, type the following command:
# fdisk -l.
Output:

Disk /dev/hda: 20.0 GB, 20060651520 bytes
255 heads, 63 sectors/track, 2438 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
   Device Boot      Start         End      Blocks   Id  System
/dev/hda1               1        1024     8225248+   b  W95 FAT32
/dev/hda2   *        1025        2438    11357955    c  W95 FAT32 (LBA)
Disk /dev/hdb: 80.0 GB, 80060424192 bytes
255 heads, 63 sectors/track, 9733 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
   Device Boot      Start         End      Blocks   Id  System
/dev/hdb1   *           1        2432    19535008+  83  Linux
/dev/hdb2            2433        2554      979965   82  Linux swap / Solaris
/dev/hdb3            2555        6202    29302560   83  Linux
/dev/hdb4            6203        9733    28362757+   5  Extended
/dev/hdb5            6203        9733    28362726   83  Linux

From above output I have two hard disks:
=> /dev/hda - 20 GB
=> /dev/hdb - 80 GB

Let us assume that you want to remove a partition from /dev/hdb disk. Type the following command:
# fdisk /dev/hdb
Output:

The number of cylinders for this disk is set to 9733.
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):

Now type p command to list partition:
Command (m for help): pOutput:

Disk /dev/hdb: 80.0 GB, 80060424192 bytes
255 heads, 63 sectors/track, 9733 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
   Device Boot      Start         End      Blocks   Id  System
/dev/hdb1   *           1        2432    19535008+  83  Linux
/dev/hdb2            2433        2554      979965   82  Linux swap / Solaris
/dev/hdb3            2555        6202    29302560   83  Linux
/dev/hdb4            6203        9733    28362757+   5  Extended
/dev/hdb5            6203        9733    28362726   83  Linux

Now let us say you want to delete /dev/hdb3 (3rd partition). Type the d command to delete a partition:
Command (m for help): d
Partition number (1-4): 3

It will prompt you for the partition number. Type 3:

Verify that partition deleted:
Command (m for help): p

Now save the changes and exit to shell prompt. Type the w command:
Command (m for help): w

Reboot the system.

Linux Partition Naming Convention ( IDE Drive Mappings )

Q. I am new to Linux and I not able to understand /dev/hdc (is it C: drive?) under Linux. This is quite confusing for a new Linux user like me. What device naming convention followed by Linux? Can you explain it in layman's term?

A. Linux does not follows DOS or Windows XP style partition names or drive names. It is true that it is a bit confusing for a new Linux user. Linux use combination of bus and . For example if you are using IDE hard disk or CDROM it is will use HD word. If you are using SCSI interface it will use SD word.
A typical home pc or laptop has 2 or 4 IDE channels as follows:

• ide0 = primary
• ide1 = secondary
• ide2 = tertiary
• ide3 = quaternary

For example:

• ide0 = primary master = hda
• ide1 = primary slave = hdb
• ide2 = secondary master = hdc
• ide3 = secondary slave = hdd

and so on...
SCSI devices are listed as devices sda, sdb, sdc, sdd, sde, sdf, and sdg in the /dev directory. Similarly, partitions on these disks can range from 1 to 16 and are also in the /dev directory.
Now each hard drive has 4 primary partitions (limit of PC x86 architecture). First partition is denoted by number 1. For example:

• First partition : /dev/hda1
• Second partition : /dev/hda2
• Third partition : /dev/hda3
• Fourth partition : /dev/hda4

You can run command fdisk -l to display list of partitions: