How to format a hard disk in Linux

This tutorials explains the detailed steps to format a hard disk in Linux server

Consider that the new hard disk has been assigned to the device file /dev/sdb.

Initially we need to create one or more Linux partitions on the new drive. We can do the same using fdisk command.

# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0xd1082b01.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
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):
As instructed, switch off DOS compatible mode and change the units to sectors by entering the c and u commands:
Command (m for help): c
DOS Compatibility flag is not set
Command (m for help): u
Changing display/entry units to sectors
In order to view the current partitions on the disk enter the p command:
Command (m for help): p
Disk /dev/sdb: 34.4 GB, 34359738368 bytes
255 heads, 63 sectors/track, 4177 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: 0xd1082b01
   Device Boot      Start         End      Blocks   Id  System

As we can see from the above fdisk output the disk currently has no partitions. So the next step is to create a new partition on the disk. In this example, we plan to create one partition which will be partition 1. Next, we need to specify where the partition will begin and end. Since this is the first partition we need it to start at the first available sector and since we want to use the entire disk we specify the last sector as the end. Note that if you wish to create multiple partitions you can specify the size of each partition by sectors, bytes, kilobytes or megabytes.

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
Partition number (1-4): 1
First sector (2048-67108863, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-67108863, default 67108863):
Using default value 67108863

Now that we have specified the partition we need to write it to the disk using the w command:
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.

The  new partition is ready now with name '/dev/sdb1'. The next step is to create a Linux file system on the partition so that the operating system can use it to store files and data. The easiest way to create a file system on a partition is to use the mkfs.ext4 utility which takes as arguments the label and the partition device.

# /sbin/mkfs.ext4 -L /data /dev/sdb1
mke2fs 1.41.12 (17-May-2010)
Filesystem label=/backup
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
2097152 inodes, 8388352 blocks
419417 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
256 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,4096000, 7962624
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem checks automatically after 36 mounts or 180 days, whichever comes first.
Use tune2fs -c or -i to override.

Now we need to mount the new partition so that it is accessible. So create a mount point for the new partition. A mount point is simply a directory or folder into which the filesystem will be mounted. In this example we will create a /data directory as the mount point.

# mkdir /data
# mount /dev/sdb1 /data

Running the mount command with no arguments shows us all currently mounted filesystems including the new one.

# mount
/dev/mapper/vg_rhel6-lv_root on / type ext4 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw,rootcontext="system_u:object_r:tmpfs_t:s0")
/dev/sda1 on /boot type ext4 (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
/dev/sr0 on /media/RHEL_6.0 x86_64 Disc 1 type iso9660 (ro,nosuid,nodev,uhelper=udisks,uid=500,gid=500,iocharset=utf8,mode=0400,dmode=0500)
/dev/sdb1 on /data type ext4 (rw) 

In order to configure the system so that the new disk is automatically mounted at the time boot we need an entry to be added to the '/etc/fstab file'. The below is the sample configuration file which shows an fstab file configured to auto mount our new partition '/data'.

/dev/mapper/vg_rhel6-lv_root /                       ext4    defaults        1 1
UUID=4a9886f5-9545-406a-a694-04a60b24df84 /boot                   ext4    defaults        1 2
/dev/mapper/vg_rhel6-lv_swap swap                    swap    defaults        0 0

tmpfs                   /dev/shm                tmpfs   defaults        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
LABEL=/data             /data                   ext4    defaults        1 2

That's all.....


Leave a Reply