Libro sobre Proxmox maestria
Chapter 3
The following table is a brief summary of the different image formats and their possible usage:
Complex file formats with additional software layers High I/O overhead
No additional software layer. Direct access to image files
.qcow2
Fixed virtual image only. Cannot be used to store dynamic images
VM takes longer to back up due to the size of image files Additional software layer, thus slower performance
Works exceptionally well with VMware infrastructure Allows dynamic virtual storage image files
NFS and directory
.vmdk
Setting up virtual machines with the wrong image format is very forgiving. You can always convert these image types from one format to another. Conversion can be done from both, CLI and GUI. Virtual disk image conversion is explained later in this chapter.
The .qcow2 type is a very stable and matured VM image format. Proxmox completely supports this file format. A VM disk created using .qcow2 is much smaller since by default it creates thin-provisioned disk images. For example, an Ubuntu VM created with 50 GB storage space may have an image file with a size around 1 GB. As a user stores data in the VM, this image file will grow gradually. The .qcow2 image format allows an administrator to overpopulate shared storage by over provisioning VMs with the .qcow2 image file. This is not a problem if users do not store data rapidly and fill up their virtual machines. In that case, the shared storage will run out of space to accommodate all the growing virtual image files. Available storage space should be regularly monitored in such an environment. It is a good practice to add additional storage space when the overall storage space consumption reaches around 80 percent.