How to add new hard disk in centos
Finding the New Hard Drive in CentOS 6
Assuming the drive is visible to the BIOS it should automatically be detected by the operating system. Typically, the disk drives in a system are assigned device names beginning hd or sd followed by a letter to indicate the device number. For example, the first device might be /dev/sda, the second /dev/sdb and so on.
The following is output from a system with only one physical disk drive:
# ls /dev/sd* /dev/sda /dev/sda1 /dev/sda2
This shows that the disk drive represented by /dev/sda is itself divided into 2 partitions, represented by /dev/sda1 and /dev/sda2.
The following output is from the same system after a second hard disk drive has been installed:
# ls /dev/sd* /dev/sda /dev/sda1 /dev/sda2 /dev/sdb
As shown above, the new hard drive has been assigned to the device file /dev/sdb.
Creating Linux Partitions
The next step is to create one or more Linux partitions on the new disk drive.
# mkfs.ext4 /dev/sdb
Mounting a File System
Now that we have created a new file system on the Linux partition of our new disk drive we need to mount it so that it is accessible. In order to do this we need to create a mount point. A mount point is simply a directory or folder into which the file system will be mounted. For the purposes of this example we will create a /backup directory to match our file system label (although it is not necessary that these values match):
# mkdir /mnt/backup
The file system may then be manually mounted using the mount command:
# mount /dev/sdb1 /mnt/backup
Now All Done.