LVM2

Andreas is a RHEL Engineer at Red Hat. He is going to master LMV2. Please answer the following questions. Use the term "Free Software" vice "open source". Use the term "GNU/Linux" vice "Linux", unless you are referring to the Linux kernel.

  1. What is LVM2 and what problem does it solve?
  2. Is LVM2 Free Sofware? If so, under which license?
  3. What is the history of LVM2?
  4. What are the strengths and weaknesses of LVM2?
  5. Please show and fully explain many examples of LVM2 commands run on a modern RHEL server.

LVM2 for Andreas, the Red Hat RHEL Engineer

LVM2 (Logical Volume Manager 2) is a Free Software tool for GNU/Linux systems that allows for flexible and granular management of physical storage devices. It abstracts away the underlying physical disks and creates a pool of logical volumes that can be resized, moved, and mirrored for increased flexibility and resilience.

Problem Solved:

LVM2 tackles the limitations of traditional partitioning by offering:

  • Dynamic resizing: Grow or shrink volumes without needing to recreate partitions.
  • Volume pooling: Combine multiple physical disks into a single virtual disk for easier management.
  • Mirroring and striping: Create redundant copies of data or distribute it across disks for performance improvements.
  • Snapshotting: Take point-in-time backups of volumes for disaster recovery.
  • Thin provisioning: Allocate storage on-demand, maximizing disk utilization.

Free Software and License:

Yes, LVM2 is Free Software under the GNU General Public License (GPL) version 2. This means anyone can use, modify, and redistribute the software without restrictions, furthering its adoption and development within the GNU/Linux community.

History of LVM2:

  • 1998: LVM1 released by Heinz Mauer.
  • 2001: LVM2 development begins, introducing significant improvements in scalability and features.
  • 2005: LVM2 becomes widely adopted in major GNU/Linux distributions.
  • 2017: LVM3 announced, focusing on integration with containerized workloads and cloud storage.

Strengths and Weaknesses of LVM2:

Strengths:

  • Flexible and dynamic storage management.
  • Increased data availability and resilience.
  • Improved storage utilization and efficiency.
  • Easy integration with various disk types and technologies.

Weaknesses:

  • Increased complexity compared to traditional partitioning.
  • Potential for data loss if not configured or managed correctly.
  • Requires kernel support and specific tools for administration.

Examples of LVM2 Commands on RHEL:

1. Create a volume group:

vgcreate myvg /dev/sdc /dev/sdd

This creates a volume group named myvg using physical disks /dev/sdc and /dev/sdd.

2. Create a logical volume from a volume group:

lvcreate -L 10G -n mylv myvg

This creates a logical volume named mylv with a size of 10GB within the myvg volume group.

3. Extend a logical volume:

lvextend -L +5G mylv

This expands the mylv logical volume by an additional 5GB.

4. Reduce a logical volume:

lvreduce -L 2G mylv

This shrinks the mylv logical volume by 2GB.

5. Create a mirror of a logical volume:

lvcreate -m 2 -L 10G -n mirrorlv myvg

This creates a mirrored logical volume named mirrorlv with a size of 10GB within the myvg volume group. The data will be mirrored across two physical disks.

6. Take a snapshot of a logical volume:

lvcreate -s -L 5G -n snapshot mylv

This creates a snapshot named snapshot of the mylv logical volume with a size of 5GB. The snapshot can be used for recovery purposes.

7. Display information about logical volumes:

lvdisplay

This command displays information about all logical volumes in the system.

Remember: These are just a few examples, and LVM2 offers a wide range of commands and features. Always consult the official documentation for detailed instructions and best practices.

By mastering LVM2, Andreas can unlock the full potential of storage management on his RHEL systems, enhancing flexibility, resilience, and efficiency.

This article was updated on December 13, 2023