The virtual disk of a virtual machine is a hard disk image. Virtual disks are stored on a local or network storage.

General information 

Logical Volume Manager is a subsystem that allows using different areas of a hard drive and/or areas from different hard drives as a single logical volume.

LVM is used for the following purposes:

  • physical volumes (PV, Physical Volume) — disk partitions or entire unpartitioned disks;
  • volume groups (VG, Volume Group) — physical volumes grouped into a single disk;
  • logical volumes (LV, Logical Volume) — partitions created on physical space of the volumes group.

An LVM-storage supports one format of virtual disk format — RAW. Learn more in the official documentation.

Peculiarities in VMmanager

  • VMmanager does not configure LVM on the cluster node. The volume group name must be specified manually before adding a node into the cluster; 
  • Only VM disks are stored in LVM each of them in a separate LV with the name "<vm_id>_<vm_name>". VM and OS images are stored outside the LVM; 
  • The VG is displayed in Nodes → node card → Disk space (a separate section).

How nodes with LVM are added 

When adding a cluster node with LVM, VMmanager calculates the number of VG on the node and searches for the VG with the specified name: 

  • if it finds one or several VG with the appropriate name, the node will be added;
  • if no VGs are found, the error message will be shown and the node won't be added; 
  • if VMmanager finds one VG with a different name it will offer to rename it; 
  • if VMmanager finds several VG but their names do not match it will show the error message and ask to rename them manually. The node creation will terminate.