LVM (Logical Volume Manager) is a storage device management technology for Linux that abstracts physical storage devices to create pools of storage that are independent of the layout of the underlying physical devices. This enables more flexibility and control when administering storage devices.
LVM provides an abstraction on top of physical storage devices to the Linux kernel. It sits between the physical block devices and the kernel to provide logical volume management.
Most modern Linux distributions are LVM-aware to the point of being able to have their root file systems on a logical volume.
Main use cases:
- Overcommit of storage through thin provisioning
- Ability to extend volumes and volume groups dynamically
- Merging of multiple physical disks into a single big logical volume
We create one PV (physical volume) for each physical disk (or partition). We can then assign multiple physical volumes to a VG (volume group). This volume group is a big pool of storage that can span multiple physical disks. Then we can create one or more LV (logical volume) on top of that volume group. The logical volumes appear to the Linux kernel as normal block devices, so we can then make a file system on top of that volume and use it just like a physical disk.
References
https://www.reddit.com/r/linux4noobs/comments/8gvj0j/how_does_lvm_work_exactly/
https://www.digitalocean.com/community/tutorials/an-introduction-to-lvm-concepts-terminology-and-operations