LVM
Please explain Physical Volumes, Physical Volume Groups, and Logical Volumes in as simple terms as possible, and please explain the commands associated with each topic. Assume that the learner is preparing for the LFCS exam on a RHEL-based system.
In Linux systems, Logical Volume Management (LVM) is a technique used to manage storage devices. LVM provides a way to manage hard disks and other storage devices in a flexible and scalable way. There are three main concepts in LVM: Physical Volumes, Physical Volume Groups, and Logical Volumes.
- Physical Volumes (PV): These are the physical storage devices, such as hard drives, that are used for LVM. A Physical Volume is a partition or a whole disk that is designated for use with LVM.
Commands associated with Physical Volumes:
pvcreate: This command is used to initialize a disk or a partition as an LVM Physical Volume.pvdisplay: This command displays information about LVM Physical Volumes on the system.pvresize: This command is used to resize an LVM Physical Volume.pvmove: This command is used to move data from one Physical Volume to another.
- Physical Volume Groups (PVG): These are groups of Physical Volumes that are combined together to create a larger pool of storage. A Physical Volume Group is a container for one or more Physical Volumes.
Commands associated with Physical Volume Groups:
vgcreate: This command is used to create an LVM Physical Volume Group.vgdisplay: This command displays information about LVM Physical Volume Groups on the system.vgextend: This command is used to add an LVM Physical Volume to an existing Physical Volume Group.vgreduce: This command is used to remove an LVM Physical Volume from an existing Physical Volume Group.
- Logical Volumes (LV): These are virtual partitions that are created from the storage pool provided by the Physical Volume Group. Logical Volumes can be resized dynamically, and they can span across multiple Physical Volumes.
Commands associated with Logical Volumes:
lvcreate: This command is used to create a Logical Volume.lvdisplay: This command displays information about LVM Logical Volumes on the system.lvresize: This command is used to resize an LVM Logical Volume.lvextend: This command is used to extend an LVM Logical Volume by adding more space from the Physical Volume Group.lvreduce: This command is used to shrink an LVM Logical Volume by removing space from it.lvmove: This command is used to move an LVM Logical Volume from one Physical Volume to another.
By understanding these LVM concepts and the associated commands, you can manage storage devices in a more flexible and scalable way on a RHEL-based system.