In starting with cloud and virtualized systems, it’s important to understand how to apply Hypervisor. Starting to work with a virtual machine may be advantageous as it’s an efficient and isolated duplicate of a real machine. It is highly available and it enables fast disaster recovery.
Virtualization technology also expands the capabilities of the hardware, helps to control IT-related costs, and helps you improve your system’s reliability and security.
In technical terms, a hypervisor is a hardware virtualization technique that allows multiple guest operating systems (OS) to run on a single host system at the same time. The guest OS shares the hardware of the host computer, such that each OS appears to have its own processor, memory, and other hardware resources.
A hypervisor is also known as a virtual machine manager (VMM).
In popping the History, The term hypervisor was first coined in 1956 by IBM to refer to software programs distributed with IBM RPQ for the IBM 360/65. The hypervisor program installed on the computer allowed the sharing of its memory.
As an integral component, hypervisor allows for physical devices to share their resources amongst virtual machines running as guests onto the top of that physical hardware. To further clarify the technology, it’s important to analyze a few key definitions:
Type I Hypervisor is also called as “native” or “bare-metal” hypervisors. This type of hypervisor deployed as a bare-metal installation. The hypervisor will communicate directly with the underlying physical server hardware. In other words, the hypervisor runs directly on the host’s hardware to control the hardware and manage the guest virtual machines.
For high-performance needs and advanced resource control, the best option for virtualization is a “bare-metal” hypervisor. The reason for this is the bare metal hypervisors use the smallest amount of resources while at the same time giving you the advantage of being able to prioritize or restrict virtual machine usage and guarantee virtual machine resource allocation.
Consoles can be centralized to provide a single dashboard that makes it easier to monitor a larger number of VMs and hosts but it essentially requires a better set of management and automation tools for bare-metal hypervisors.
Examples for type I or bare-metal hypervisors are VMware ESX and ESXi, Microsoft Hyper-V, Oracle VM, etc.
Type II Hypervisor is also called a “hosted” hypervisor. Here, the hypervisor runs just like any other application on the system i.e, on the conventional operating system. The hypervisor separates the host OS from the guest OS. For example, a server running Windows Server 2008R2 can have VMware Workstation 8 installed on top of that OS.
Hosted virtualization hypervisors are easy to install, uncomplicated to use, and do not require specialized skills to maintain and thus have obvious economic benefits. The installation of the majority of hosted hypervisors is similar to that of a windows application.
Hosted hypervisors need to be individually managed which is time-consuming and laborious when you have large infrastructures.
Examples for type II or hosted hypervisors are VMware Workstation/Fusion/Player, Microsoft Virtual PC, Oracle VM VirtualBox, etc.
Understand the need and create a Checklist on the following basis:
Virtual machines are separated from each other even though they run on the same physical hardware and hence if one virtual machine experiences an error, malware attack, or a crash, it does not extend to other machines.
As virtual machines are separated or independent of the underlying physical hardware, they are very mobile and can be migrated between remote or local virtualized servers that are attached to physical hardware.
Two choices of where to place your high availability, either in the virtualization hypervisors themselves or to deploy load balancers, both virtual or hardware appliances that offer this functionality. High availability ensures business continuation even in the event that a virtualized hypervisor fails. VMotion from VMware is considered to one of the best high availability solutions as it comes packed with features fault tolerance is also included. Microsoft Hyper-V has improved its high availability options recently but is considered by some to be a less integrated solution compared with VMware. XenServer from Citrix needs to rely on other third-party products to be set up in high availability mode. Hosted virtualization hypervisors don’t normally come with high availability options, for this reason, you should consider using dedicated virtual or physical load balancers to deal with any VM failures that may occur.
Essentially better set of management and automation tools for bare-metal virtualization hypervisors required. Consoles can be centralized to provide a single dashboard that makes it easier to monitor a larger number of VMs and hosts. A second advantage for the bare metal option is the large number of 3rd party automation and management tools that are available too. Hosted hypervisors need to be individually managed and this limitation makes management that much more time-consuming and laborious when you have large infrastructures.