Local storages

A VM virtual disk is an image of the hard drive. Virtual disks are kept on a network or local devices (a storage).

This article describes the types and functionality of local storages supported by VMmanager.

Supported local storages:

• DIR;
• LVM.

DIR

A file system. Normally, this storage has one section in one disk.

LVM

Logical volume manager is a subsystem that allows using different areas of the same hard drive and/or areas of different hard drives as one logical volume.

The file system size of logical volumes is not limited with just one disk, as the volume can be located in different disks and sections.

LVM can have the following designations:

• PV (Physical Volume) —  physical volume (disk sections or unsectioned disks);;
• VG (Volume Group) —  a group of volumes (a few physical volumes (PV) united under the same group and building a single disk);
• LV (Logical Volume) — a section created in the physical space of a group of volumes (VG).

When a new LVM storage is created, VMmanager checks whether there is a group of volumes (VG) with the specified storage name.

1. If there is such group, then storage is initiated. 
2. If there is no such group, VMmanager will search for sections and hard drives allowing to create a group of volumes. A group of volumes can be located in the following sections and hard drives:

1. 1. hard drive without any section;
   2. hard drive section with linux-lvm inside.
2. If such sections or hard drives are not found, VMmanager will not be able to create an LVM storage on the physical server.

LVM storage can only support RAW format for virtual disks. For more information on LVM please refer to its official documentation.

Peculiarities of local storages

There is a number of difference in the virtual disk management depending on a local storage type and virtual disk format. In the table you can see the main peculiarities: