LVM2 TUTORIAL PDF

View All Introduction LVM, or Logical Volume Management, is a storage device management technology that gives users the power to pool and abstract the physical layout of component storage devices for easier and flexible administration. Utilizing the device mapper Linux kernel framework, the current iteration, LVM2, can be used to gather existing storage devices into groups and allocate logical units from the combined space as needed. In this guide, we will cover how to manage your storage devices with LVM. We will show you how to display information about volumes and potential targets, how to create and destroy volumes of various types, and how to modify existing volumes through resizing or transformation. We will be using an Ubuntu Prerequisites In order to follow along, you should have access to an Ubuntu

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Become an author Introduction LVM, or Logical Volume Management, is a storage device management technology that gives users the power to pool and abstract the physical layout of component storage devices for easier and flexible administration.

Utilizing the device mapper Linux kernel framework, the current iteration, LVM2, can be used to gather existing storage devices into groups and allocate logical units from the combined space as needed. The main advantages of LVM are increased abstraction, flexibility, and control. Volumes can be resized dynamically as space requirements change and migrated between physical devices within the pool on a running system or exported easily.

LVM also offers advanced features like snapshotting, striping, and mirroring. In this guide, we will briefly discuss how LVM works and then demonstrate the basic commands needed to get up and running quickly. LVM Architecture and Terminology Before we dive into the actual LVM administrative commands, it is important to have a basic understanding of how LVM organizes storage devices and some of the terminology it employs.

The basic layers that LVM uses, starting with the most primitive, are. Physical Volumes: LVM utility prefix: pv Description: Physical block devices or other disk-like devices for example, other devices created by device mapper, like RAID arrays are used by LVM as the raw building material for higher levels of abstraction.

Physical volumes are regular storage devices. LVM writes a header to the device to allocate it for management. Volume Groups: LVM utility prefix: vg Description: LVM combines physical volumes into storage pools known as volume groups. Volume groups abstract the characteristics of the underlying devices and function as a unified logical device with combined storage capacity of the component physical volumes. Logical Volumes: LVM utility prefix: lv Description: A volume group can be sliced up into any number of logical volumes.

Logical volumes are functionally equivalent to partitions on a physical disk, but with much more flexibility. Logical volumes are the primary component that users and applications will interact with. In summary, LVM can be used to combine physical volumes into volume groups to unify the storage space available on a system. Afterwards, administrators can segment the volume group into arbitrary logical volumes, which act as flexible partitions. What are Extents?

Each volume within a volume group is segmented into small, fixed-size chunks called extents. The size of the extents is determined by the volume group all volumes within the group conform to the same extent size. The extents on a physical volume are called physical extents, while the extents of a logical volume are called logical extents. A logical volume is simply a mapping that LVM maintains between logical and physical extents.

Because of this relationship, the extent size represents the smallest amount of space that can be allocated by LVM. Extents are behind much of the flexibility and power of LVM. The logical extents that are presented as a unified device by LVM do not have to map to continuous physical extents.

LVM can copy and reorganize the physical extents that compose a logical volume without any interruption to users. Logical volumes can also be easily expanded or shrunk by simply adding extents to or removing extents from the volume. We will start by walking through a basic procedure that will use two physical disks to form four logical volumes. Warning: Make sure that you double-check that the devices you intend to use with LVM do not have any important data already written to them.

Using these devices within LVM will overwrite the current contents. If you already have important data on your server, make backups before proceeding. Add the Physical Volumes to a Volume Group Now that we have created physical volumes from our devices, we can create a volume group. Most of the time, you will only have a single volume group per system for maximum flexibility in allocation. Creating Logical Volumes from the Volume Group Pool Now that we have a volume group available, we can use it as a pool that we can allocate logical volumes from.

Unlike conventional partitioning, when working with logical volumes, you do not need to know the layout of the volume since LVM maps and handles this for you. You only need to supply the size of the volume and a name. We must pass in the volume group to pull from, and can name the logical volume with the -n option. To specify the size directly, you can use the -L option.

If, instead, you wish to specify the size in terms of the number of extents, you can use the -l option. Logical volume "www" created. Logical volume "db" created. We can also provide a percentage and a unit to better communicate our intentions. Format and Mount the Logical Volumes Now that we have logical volumes, we can use them as normal block devices.

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A Beginner's Guide To LVM - Page 2

Features of LVM include: Create, resize, move and delete partitions on the disks Manage the space of multiple hard disks by creating logical volumes Operate on the system without knowing the total space of any partition Space of any partition can be resized or assigned to any low space partition at any time Change the file system of any existing partition or remove any partition from the system quickly Create snapshots of any running system Creates striped logical volumes of the disks Creation of software RAID partitions or standard partitions of a single disk Volumes of the disk can be extended on the fly to provide more flexibility to the system based on requirements. Three main components of LVM are physical volumes, logical volumes and volume groups. The block devices that are used to store logical volumes are called physical volumes. Each logical volume holds a file system which corresponds to a partition and a unique name is assigned for each logical volume. The collection of all physical and logical volumes is called volume group.

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How to Create LVM Partition in Linux - LVM Tutorial

Become an author Introduction LVM, or Logical Volume Management, is a storage device management technology that gives users the power to pool and abstract the physical layout of component storage devices for easier and flexible administration. Utilizing the device mapper Linux kernel framework, the current iteration, LVM2, can be used to gather existing storage devices into groups and allocate logical units from the combined space as needed. The main advantages of LVM are increased abstraction, flexibility, and control. Volumes can be resized dynamically as space requirements change and migrated between physical devices within the pool on a running system or exported easily. LVM also offers advanced features like snapshotting, striping, and mirroring. In this guide, we will briefly discuss how LVM works and then demonstrate the basic commands needed to get up and running quickly.

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