Managing logical volumes with LVM

Although we can share the entire disk space or disk partitions, it really makes sense to share just the disk space that a client service requires. So, for example, if a web server requires 20 GB of space for web files, we can share just that absolute space, rather than the whole disk that may be terabytes in size. To do so, we will create logical volumes and share these as block devices. To implement LVMs, we create three objects:

• Physical volumes: This represents the raw disk space as disk partitions. When we use partitions, the partition type should be set to Linux LVM with an ID of 8E using the fdisk partitioning tool.
• Volume groups: This aggregates physical volumes together so that the disk space can be consumed to logical volumes.
• Logical volumes: This represents the block device that can be shared. It consumes space that is allocated from volume groups.

On the demonstration RHEL 7.1 system that we will use for this course, I have three disks attached...