Linux RHCSA Part 5 - Disks and partitions - Creating partitions - fdisk , parted , partprobe

Disk partitioning is one of the many steps required when preparing a system for operation. In every operating system, physical disks are divided into logical partitions, providing space for data storage. There are also special types of partitions, such as RAID, which offer increased performance, redundancy, or both at once. LVM, similar to RAID, is a more advanced type of partition that allows for easier management by creating larger data storage spaces. The only point to keep in mind is to have a well-thought-out action plan before you start creating and organizing partitions. You should consider what partition size you will need in the future and how the filesystem will grow. How the data will be distributed. Planning will make system administration more pleasant and save you the pain associated with migrating partitions.  

PRIMARY PARTITIONS

Working with disks is an important part of managing space for data storage in the system. Partitions define the amount of space for the system and its users. During system installation, there are automatic partition wizards, but you can always add new ones if the need arises. We have two different tools at our disposal for partitioning disks, these are : 

# fdisk       - Disk partitioning tool 

# parted     - Another disk partitioning tool 

While "fdisk" is more common and frequently used, there is a gradual trend towards using "parted" more often because it is more flexible. You can also use the "cat" command on the "/proc" file containing system information. This file is created when the system starts and contains current information regarding its parameters. 

In the result, you can see different disks : hda, hdb, hdc, and hdd. The first two letters determine which disk we are dealing with : SCSI (sd) or IDE (hd). The next letter (a,b,c,d...) indicates which disk it is in order, and the digit at the end informs which partition it is on the given disk. Above in the example, you can see that we have 4 disks (a,b,c,d), where the first one (a) has 3 partitions (0,1,2). Let's start with the "fdisk" command.

You can just as well use the second command : # parted 

parted command syntax : # parted [options] device [options]

parted command options: 

• -l     - Partition table 
• -s    - Do not use prompt in interactions (use in scripts) 

To begin, we will use "fdisk" to create a partition.

Step 1 - select disk : # fdisk /dev/hdb

Step 2  - See what options are available: "m" command for help

• a     - toggle bootable flag 
• b     - edit bsd disk label 
• c     - toggle DOS compatibility flag
• d     - delete a partition
• l      - list known partition types 
• m    - display menu
• n     - new partition
• o     - create a new empty DOS partition table
• p     - display partition table 
• q     - quit without saving changes 
• s     - create a new empty SUN disklabel
• t      - change partition ID 
• u     - change display units 
• v     - verify partition table 
• w    - write table to disk and exit 
• x     - extra functionality (experts only) 

Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-1044, default 1):
Use default value 1
Last cylinder or +size or +sizeM or +sizeK (1-1044, default1044): +4294M


Since the disk was divided in half using megabytes as the unit, you can use the syntax :

• +sizeM for megabytes 
• +sizeK for kilobytes
• +size for cylinders