4. Disk Partitioning

This lesson provides a practical guide to managing filesystems by partitioning a disk, such as a USB drive. If you don't have a spare drive, you can still follow along to understand the concepts.

First, we'll need to partition our disk. There are many tools available for this task:

• fdisk: A basic command-line partitioning tool; it does not support GPT.
• parted: A powerful command-line tool that supports both MBR and GPT partitioning.
• gparted: The graphical version of parted. For users who prefer a visual interface, gparted is an intuitive tool, often considered a great gparted windows alternative.
• gdisk: Similar to fdisk, but it only supports GPT.

We will use parted for our examples.

Listing Existing Partitions

Before making changes, it's crucial to identify your disk and its current layout. A quick way to do this is with the sudo parted -l command, which lists the partition tables for all connected block devices.

sudo parted -l

This command helps you find the correct device name, such as /dev/sdb, before you begin modifying it.

Launching Interactive Mode

To start making changes, launch parted in interactive mode. Let's assume your target device is /dev/sdb.

sudo parted

You will enter the parted tool's shell, where you can run commands to manage your device's partitions.

Selecting a Device

Once inside the parted shell, you must select the disk you want to modify. Be very careful to choose the correct one to avoid data loss.

select /dev/sdb

Viewing the Partition Table

Use the print command to display the partition table of the selected disk.

(parted) print
Model: ATA VBOX HARDDISK (scsi)
Disk /dev/sdb: 10.7GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:

Number  Start   End     Size    Type      File system  Flags
 1      1049kB  10.7GB  10.7GB  primary   ext4         boot

This output shows available partitions on the device. The Start and End columns indicate where each partition is located on the disk.

Creating a Partition

The mkpart command creates a new partition. You need to specify the partition type (e.g., primary), an optional filesystem type, and the start and end points.

mkpart primary ext4 1MB 5000MB

This command creates a primary partition formatted with ext4, starting at 1MB and ending at 5000MB.

Resizing a Partition

You can also resize an existing partition with the resizepart command. You'll need the partition number and the new end point.

resizepart 1 8000MB

This command resizes partition number 1 to end at the 8000MB mark. Note that this only changes the partition size; you may still need to resize the filesystem itself using other tools (like resize2fs).

parted is a very powerful tool. Always double-check your commands before executing them to prevent accidental data loss.