How to Use the Command 'lvdisplay' (with examples)

Logical Volume Manager (LVM) is a powerful tool used in Unix-like operating systems, such as Linux, to manage disk drives and other storage devices. The lvdisplay command is part of the LVM package and is utilized to display detailed information about logical volumes on your system. Logical volumes allow for flexible disk management, enabling features like resizing and snapshotting without downtime, which is one of the many benefits of using LVM over traditional partitioning methods.

Understanding how to use lvdisplay can be crucial for system administrators who need to monitor, manage, and ensure the reliability of storage resources.

Use case 1: Display information about all logical volumes

Code:

sudo lvdisplay

Motivation:

System administrators often need to get an overview of all logical volumes present on a machine. This command provides a comprehensive list of all logical volumes, along with critical details like size, attributes, allocation policy, and more. This is especially useful in troubleshooting storage issues or for simply understanding the current storage setup.

Explanation:

• sudo: This command is executed with superuser privileges because LVM operations typically require elevated permissions. Access to volume information should be restricted to authorized users to maintain system integrity and security.

• lvdisplay: This is the command itself. It queries the system and retrieves information about all logical volumes, presenting it in a human-readable format.

Example output:

--- Logical volume ---
LV Name                /dev/vg0/home
VG Name                vg0
LV UUID                ZT2eq1-ybYE-mJOb-ruuQ-OU3O-8S4F-38e7sT
LV Write Access        read/write
LV Creation host, time server.domain.com, 2023-10-05 14:23:07 +0000
LV Status              available
# open                 1
LV Size                100.00 GiB
Current LE             25600
Segments               1
Allocation             inherit

--- Logical volume ---
LV Name                /dev/vg1/data
...

The above output shows details for each logical volume, like name, volume group, size, and status, providing a clear snapshot of the logical volumes defined on the system.

Use case 2: Display information about all logical volumes in volume group vg1

Code:

sudo lvdisplay vg1

Motivation:

There might be a need to focus on a particular volume group to which your logical volumes belong, especially in environments with multiple volume groups in place. This command limits the output only to logical volumes belonging to the specified volume group vg1, allowing users to quickly and efficiently monitor or troubleshoot specific storage configurations without the noise of unrelated data.

Explanation:

• sudo: Again, superuser privileges are required to run this command to ensure that the user has the necessary permissions to access LVM data.

• lvdisplay: The command used to fetch details of logical volumes.

• vg1: This argument specifies the volume group vg1, filtering the output to show information only about its logical volumes.

Example output:

--- Logical volume ---
LV Name                /dev/vg1/lv1
VG Name                vg1
LV UUID                VGVn3X-7WMB-IQjE-3E6r-MxPm-TtT1-nU4Ias
LV Write Access        read/write
LV Creation host, time server.domain.com, 2023-10-05 14:23:07 +0000
LV Status              available
# open                 2
LV Size                50.00 GiB
Current LE             12800
Segments               1
Allocation             inherit

--- Logical volume ---
LV Name                /dev/vg1/lv2
...

The output is limited to logical volumes within vg1, making it easier to manage a specific segment of your storage infrastructure.

Use case 3: Display information about logical volume lv1 in volume group vg1

Code:

sudo lvdisplay vg1/lv1

Motivation:

If you need detailed information about a specific logical volume, such as lv1 within the volume group vg1, this command offers a targeted inspection. It’s particularly useful for investigating issues, planning modifications, or learning specific details like the volume’s exact size or properties.

Explanation:

• sudo: Running as superuser grants the necessary access to view detailed logical volume information.

• lvdisplay: Remains the command used to display logical volume details.

• vg1/lv1: This specifies both the volume group and the logical volume, allowing precise control over which logical volume’s details are retrieved and displayed.

Example output:

--- Logical volume ---
LV Name                /dev/vg1/lv1
VG Name                vg1
LV UUID                VGVn3X-7WMB-IQjE-3E6r-MxPm-TtT1-nU4Ias
LV Write Access        read/write
LV Creation host, time server.domain.com, 2023-10-05 14:23:07 +0000
LV Status              available
# open                 2
LV Size                50.00 GiB
Current LE             12800
Segments               1
Allocation             inherit
Block device           255:2

The detailed output for lv1 within the vg1 volume group includes all pertinent details about the specific logical volume, aiding in precise management and diagnostics.

Conclusion:

The lvdisplay command is a valuable utility for any system administrator working with LVM. It offers detailed insights into logical volumes, enabling effective management and troubleshooting. By understanding and utilizing these command examples, administrators can maintain system storage with confidence and precision.