Maximizing Flexibility: A Guide to LVM Concepts, Terminology, and Operations

Explore the fundamentals of LVM – Logical Volume Management – and learn how to manage your storage devices for maximum flexibility. Dive into the world of storage abstraction and grasp the terminology along with basic operations.

Introduction

LVM, or Logical Volume Management, is a technology for managing storage devices that provides users with the ability to group and abstract the physical arrangement of component storage devices for flexible management. The current implementation, LVM2, utilizes the Device Mapper Linux Kernel framework to group existing storage devices and allocate logical units from the combined storage space as needed.

Architecture and Terminology of LVM

Before delving into LVM administrative commands, it’s important to have a basic understanding of how LVM organizes storage devices and what terminology it employs.

Management Structures of LVM

LVM works by laying abstractions over physical storage devices. The basic levels that LVM utilizes, starting with the most primitive, are:

• Physical Volumes: pv…
• Volume Groups: vg…
• Logical Volumes: lv…

Understanding Extents

Each volume within a volume group is divided into small, fixed-sized chunks called extents. The size of the extents is determined by the volume group. All volumes within the group correspond to the same extent size.

Common Use Cases

Now that you’re familiar with some of the terminology and structures, you can explore some common applications of LVM. You’ll start with a procedure involving two physical hard drives to create four logical volumes.

Formatting and Mounting the Logical Volumes

Once you have logical volumes, you can use them like regular block devices.

The logical devices are available in the /dev directory like other storage devices. You can find them in two places:

• /dev/volume_group_name/logical_volume_name
• /dev/mapper/volume_group_name-logical_volume_name

Conclusion

You now have an understanding of the various components managed by LVM to create a flexible storage system and how to operationalize storage devices in an LVM environment.