This article covers best practices when backing up hypervisors and the virtual machines contained within.
A hypervisor is a host of virtual machines that can hold as many virtual machines as resources are available. The hypervisor holds the data for the VMs in a data store.
Examples of Hypervisors:
- VMWare; VSphere; ESXi
- Microsoft Hyper-V
- Citrix Hypervisor (XenServer)
- Oracle VirtualBox
These all act as a software front end for the mass management of virtual machines that are all part of the same physical machine.
2.1 Virtual Machines
Virtual machines (VMs) are servers that are housed within the hypervisor, and run as independent servers with resources. They pool their resources from the same physical machine, as shown in Figure 1.
Figure 1 - Virtual Servers
In the above example, since you have 5 servers and a hypervisor, you are in control of 6 different servers.
3. Additional Information
Disks partitioned for a hypervisor have two separate partitions. One partition holds the information about your hypervisor and the hypervisor "operating system." The other partition handles your data store, which is where the virtual machines reside.
A hypervisor's operating system resides on "C:". the information about the virtual machines (the data store) resides on "D:" or any other volume.
If you are not using agentless backups, you should install the backup agent software on the hypervisor and exclude the data volume (back up C: and exclude the D: partition). The virtual machines that reside on the data store should all be backed up and all desired partitions should be backed up on the virtual machines. The following are the benefits of this setup:
- This kind of installation gives you the greatest control over your machines.
- If your hypervisor becomes corrupted, you have the ability to restore information regarding the operating system drive.
- If one machine becomes corrupted, you have the ability to export and restore the information on that singular virtual machine.
- If the entire data store becomes corrupted, you have the ability to restore servers one at a time.
- If you need to migrate other machines to other hypervisors or even physical machines, you'll have the granularity and flexibility to restore those machines.