Managing Logical Volume Management (LVM) on RedHat 8 / CentOS 8

Introduction

Logical Volume Management (LVM) is a powerful storage management tool that allows for flexible and efficient management of storage devices on Red Hat 8 and CentOS 8 systems. LVM provides features like volume resizing, snapshot creation, and striping, making it an essential component for system administrators and IT professionals. In this blog, we'll dive into the fundamentals of LVM configuration and management on Red Hat 8 and CentOS 8.

Understanding LVM Components

Before we start configuring LVM, let's understand the essential components of LVM:

1. Physical Volumes (PVs): These are physical storage devices like hard drives, SSDs, or partitions. PVs are the building blocks of LVM.

2. Volume Groups (VGs): A VG is a collection of one or more PVs. It acts as an intermediary layer between PVs and logical volumes.

3. Logical Volumes (LVs): LVs are virtual partitions created from VGs. They can be thought of as equivalent to regular disk partitions.

Now, let's explore how to configure and manage LVM on Red Hat 8 / CentOS 8.

 Step 1: Installation

If LVM is not already installed, you can install it using the following command:

sudo dnf install lvm2

Step 2: Creating Physical Volumes (PVs)

To use LVM, you first need to designate one or more disks or partitions as Physical Volumes. Use the `pvcreate` command for this purpose. For example:

sudo pvcreate /dev/sdb1 /dev/sdc1

Step 3: Creating a Volume Group (VG)

Once you have PVs, you can create a Volume Group. This step groups together your PVs into a logical unit. For example:

sudo vgcreate myvg /dev/sdb1 /dev/sdc1

Step 4: Creating Logical Volumes (LVs)

With your Volume Group set up, you can now create Logical Volumes. These are the virtual partitions that you can use to store data. Here's how to create an LV:

sudo lvcreate -n mylv -L 10G myvg

This command creates an LV named `mylv` with a size of 10 gigabytes within the `myvg` Volume Group.

Step 5: Formatting and Mounting LVs

After creating an LV, you can format it with a filesystem of your choice (e.g., ext4, xfs) and then mount it to a directory:

sudo mkfs.ext4 /dev/myvg/mylv

sudo mount /dev/myvg/mylv /mnt/mylv

Step 6: Extending LVs

One of the significant advantages of LVM is the ability to easily extend your storage. If you need to increase the size of an LV, you can do so without disrupting your system. Here's how you can extend an LV:

# Extend the LV by 5GB

sudo lvextend -L +5G /dev/myvg/mylv

For More Details

# Resize the filesystem to utilize the additional space

sudo resize2fs /dev/myvg/mylv

Step 7: Snapshots and Other Advanced Features

LVM offers advanced features like snapshots, mirroring, and striping. Snapshots allow you to create point-in-time copies of your LVs for backup or testing purposes. 

Step 8: Monitoring and Maintenance

Regularly monitor your LVM setup using tools like `lvs`, `vgs`, and `pvs`. These commands provide information about LVs, VGs, and PVs, respectively. Additionally, consider setting up regular backups to protect your data.

Conclusion

Logical Volume Management (LVM) is a versatile tool that simplifies storage management on Red Hat 8 and CentOS 8 systems. By understanding the fundamental components and following the steps outlined in this guide, you can create, manage, and expand storage resources efficiently. Whether you are a system administrator or an IT enthusiast, LVM is an essential skill to master for effective storage management in Linux environments.