How to Extend Logical Volumes Using 'lvextend' (with examples)

The lvextend command is a powerful tool in the Linux operating system used to manage logical volumes. Logical Volume Management (LVM) allows for more flexible and efficient storage management. Specifically, lvextend is utilized to increase the size of an existing logical volume, which is a feature that comes in handy when you need more storage space on a partition without the hassle of resizing existing physical partitions or risking data integrity. The command supports several flexible options to expand storage capacity seamlessly. Below, we’ll explore different use cases of lvextend, demonstrating how it can be used to extend logical volumes effectively.

Use case 1: Increase a volume’s size to 120 GB

Code:

lvextend --size 120G logical_volume

Motivation:

Imagine you are a system administrator managing a server that runs multiple applications. One of the logical volumes on this server is getting close to its current capacity of 100 GB, and you need to increase it to accommodate an additional 20 GB of data. In such cases, using the lvextend command to resize the logical volume to a total of 120 GB ensures the server runs smoothly without any disruptions due to storage shortages. This is a proactive approach to maintain server performance and prevent potential downtime caused by lack of space.

Explanation:

• lvextend: The command itself is used to extend the size of a logical volume.
• --size 120G: The --size option specifies the new total size of the logical volume. Here, 120G indicates that the logical volume should be increased to a total of 120 gigabytes.
• logical_volume: This represents the path or the name of the logical volume that needs to be extended.

Example Output:

  Extending logical volume logical_volume to 120.00 GiB.
  Logical volume logical_volume successfully resized.

Use case 2: Increase a volume’s size by 40 GB as well as the underlying filesystem

Code:

lvextend --size +40G -r logical_volume

Motivation:

Suppose you’ve decided to add an additional feature to an application hosted on a logical volume of your server. This feature requires an extra 40 GB of space, and you need to ensure that the logical volume and the filesystem within it are expanded simultaneously. This is crucial because increasing the logical volume alone won’t automatically increase the filesystem. By using the -r flag, which stands for “resize”, you make sure that the filesystem is resized in tandem with the logical volume, simplifying the process and preventing any potential data issues or application errors.

Explanation:

• lvextend: The command used to enlarge the size of a logical volume.
• --size +40G: The --size option with a + indicates an incremental addition of 40 gigabytes to the existing size of the logical volume.
• -r: The -r flag automatically resizes the filesystem along with the logical volume.
• logical_volume: Refers to the specific logical volume to be expanded.

Example Output:

  Extending logical volume logical_volume to 40 GiB.
  Logical volume logical_volume successfully resized.
  Resizing filesystem on logical volume logical_volume.
  Filesystem on logical_volume successfully resized.

Use case 3: Increase a volume’s size to 100% of the free physical volume space

Code:

lvextend --size +100%FREE logical_volume

Motivation:

As an administrator, maximizing storage usage is often essential, especially in environments where resource efficiency is key. Imagine having a logical volume where the physical storage backing it has abundant unused space that should be put into use. By expanding the logical volume to consume all available free physical storage space, you effectively utilize your server’s hardware without acquiring additional storage devices. This use case is especially beneficial in virtual environments or situations where hardware resources are limited and need to be fully leveraged.

Explanation:

• lvextend: This is the command for enlarging the logical volumes.
• --size +100%FREE: This instructs lvextend to expand the volume by using 100% of the remaining free space available in the underlying physical volume.
• logical_volume: The path or identifier to the logical volume set to be extended.

Example Output:

  Extending logical volume logical_volume to 100% of the free physical volume space.
  Logical volume logical_volume successfully resized.

Conclusion:

The lvextend command in Linux provides a comprehensive, flexible approach to increasing storage capacity on logical volumes managed by LVM. Through the specific use cases illustrated above, we see how lvextend can be used to adjust the size of logical volumes under different scenarios, whether it is setting a new fixed size, incrementing the current size, or expanding to use all available free space. Each of these operations ensures that storage solutions remain adaptable, reliable, and efficient to suit varying administrative needs and system requirements.