VMmanager 6: Administrator guide

LVM storage

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


  • only one storage type can be used in the cluster; 
  • 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 to create a cluster with LVM


There are two ways: the minimum and maximum ones. 

  1. Go to Clusters → Add cluster.
  2. Enter the cluster Name
  3. Set the default Time zone for cluster nodes and virtual machines. 
  4. Select OS that can be installed on virtual machines on the cluster. 
  5. Select the Storage type "LVM". Click on  for advanced settings: 

    1. Enter the Volume group name (VG). 

      Note

      The VG name of future cluster nodes must match the specified name.

    2. Enter the Path for images directory. 
    3. Enter the Path for OS directory. 

      Note

      Directories for images an OS on future nodes must match with the specified paths.

  6. Specify the Overselling ratio. Learn more in the article Overselling
  7. Specify the Speed limit in Mbit/s. It will be the maximum speed for new and existing virtual machines in the cluster. To change the speed value for a certain VM go to Virtual machines → click on the VM name → Speed limit

  8. Select IP pools for virtual machines in the cluster. 
  9. Click on Add
  10. Configure the LVM on future cluster nodes: create a VG with an appropriate name and specify directories for VM and OS templates. 
  11. Connect the nodes with the configured LVM to the cluster node. Learn more in the article Managing servers in the cluster.

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.