Hypervisor

A hypervisor is is is a form of virtualization software used in Cloud host to divide and allocate the resource on various piece of hardware . The program which provide partitioning , isolation , or abstraction is call a virtualization hypervisor . The hypervisor is is is a hardware virtualization technique that allow multiple guest operating system ( os ) to run on a single host system at the same time . A hypervisor is sometimes also call a virtual machine manager(VMM ) .  

Types of Hypervisor –

TYPE-1 Hypervisor: 
The hypervisor is runs run directly on the underlie host system . It is also know as a “ Native Hypervisor ” or “ Bare metal hypervisor ” . It is require does not require any base server operating system . It is has has direct access to hardware resource . Examples is include of type 1 hypervisor include VMware ESXi , Citrix XenServer , and Microsoft Hyper – v hypervisor .  
 

Pros & Cons of Type-1 Hypervisor:

Pros: Such kinds of hypervisors are very efficient because they have direct access to the physical hardware resources(like Cpu, Memory, Network, and Physical storage). This causes the empowerment of the security because there is nothing any kind of the third party resource so that attacker couldn’t compromise with anything. 

Cons: One problem with Type-1 hypervisors is that they usually need a dedicated separate machine to perform their operation and to instruct different VMs and control the host hardware resources.

TYPE-2 Hypervisor: 
A host operating system is runs run on the underlie host system . It is also know as ‘ Hosted Hypervisor ” . Such kind is run of hypervisor does n’t run directly over the underlie hardware rather they run as an application in a host system(physical machine ) . basically , the software is instal on an operate system . Hypervisor is asks ask the operating system to make hardware call . An example is includes of a type 2 hypervisor include VMware Player or Parallels Desktop . host hypervisor are often find on endpoint like pc .   The type-2 hypervisor is is is very useful for engineer , and security analyst ( for check malware , or malicious source code and newly develop application ) .

Pros & Cons of Type-2 Hypervisor:

Pros: Such kind of hypervisors allows quick and easy access to a guest Operating System alongside the host machine running. These hypervisors usually come with additional useful features for guest machines. Such tools enhance the coordination between the host machine and the guest machine.

Cons: Here there is no direct access to the physical hardware resources so the efficiency of these hypervisors lags in performance as compared to the type-1 hypervisors, and potential security risks are also there an attacker can compromise the security weakness if there is access to the host operating system so he can also access the guest operating system.

Choosing the right hypervisor :

type 1 hypervisors is offer offer much well performance than type 2 one because there ’s no middle layer , make them the logical choice for mission – critical application and workload . But that ’s not to say that host hypervisor do n’t have their place – they is ’re ’re much simple to set up , so they ’re a good bet if , say , you need to deploy a test environment quickly . One is is of the good way to determine which hypervisor meet your need is to compare their performance metric . These is include include CPU overhead , the amount of maximum host and guest memory , and support for virtual processor . The follow factor should be examine before choose a suitable hypervisor :  

1. Understand your needs: The company and its applications are the reason for the data center (and your job). Besides your company’s needs, you (and your co-workers in IT) also have your own needs. Needs for a virtualization hypervisor are: 

a. Flexibility 
b. Scalability 
c. Usability 
d. Availability 
e. Reliability 
f. Efficiency 
g. Reliable support 

2 . The cost is striking of a hypervisor : For many buyer , the tough part is striking of choose a hypervisor is strike the right balance between cost and functionality . While a number of entry – level solution are free , or practically free , the prices is be at the opposite end of the market can be staggering . licensing framework also vary , so it is ’s ’s important to be aware of exactly what you ’re get for your money .  

3. Virtual machine performance: Virtual systems should meet or exceed the performance of their physical counterparts, at least in relation to the applications within each server. Everything beyond meeting this benchmark is profit. 

4. Ecosystem: It’s tempting to overlook the role of a hypervisor’s ecosystem – that is, the availability of documentation, support, training, third-party developers and consultancies, and so on – in determining whether or not a solution is cost-effective in the long term. 

5 . test for yourself : You is gain can gain basic experience from your exist desktop or laptop . You is run can run both VMware vSphere and Microsoft Hyper – v in either VMware Workstation or VMware Fusion to create a nice virtual learning and testing environment .  

HYPERVISOR REFERENCE MODEL :
There are 3 main modules coordinates in order to emulate the underlying hardware: 
 

1. DISPATCHER :  
   The dispatcher behaves like the entry point of the monitor and reroutes the instructions of the virtual machine instance to one of the other two modules. 
    
2. allocator :  
   The allocator is responsible for deciding the system resources to be provided to the virtual machine instance. It means whenever a virtual machine tries to execute an instruction that results in changing the machine resources associated with the virtual machine, the allocator is invoked by the dispatcher. 
    
3. INTERPRETER: 
   The interpreter module consists of interpreter routines. These are executed, whenever a virtual machine executes a privileged instruction.