Question

Your organization plans to upgrade its operating system to the newest version. The IT department identifies several legacy applications that will require significant modifications to run under the new OS. You suggest instead that they should consider supporting both the old and the new operating system by using one of the following three options:
a. virtualization
b. exokernels
c. microkernels Briefly explain how each option could provide the needed support.

Answer 1

Many IT organizations must deploy multiple servers, each operating at a fraction of their capacity, to keep pace with today’s high storage and processing demands. The result: huge inefficiencies and excessive operating costs.

Enter virtualization. Virtualization relies on software to simulate hardware functionality and create a virtual computer system. This enables IT organizations to run more than one virtual system – and multiple operating systems and applications – on a single server. The resulting benefits include economies of scale and greater efficiency.

Key Properties of Virtual Machines
VMs have the following characteristics, which offer several benefits.

Partitioning

Run multiple operating systems on one physical machine.
Divide system resources between virtual machines.
Isolation

Provide fault and security isolation at the hardware level.
Preserve performance with advanced resource controls.
Encapsulation

Save the entire state of a virtual machine to files.
Move and copy virtual machines as easily as moving and copying files.
Hardware Independence

Provision or migrate any virtual machine to any physical server.

Exokernel is a type of operating system developed at the Massachusetts Institute of Technology that seeks to provide application-level management of hardware resources. The exokernel architecture is designed to separate resource protection from management to facilitate application-specific customization.

Exokernels are typically small in size because of their limited operability.

Some of the features of exokernel operating systems include:

Better support for application control
Separates security from management
Abstractions are moved securely to an untrusted library operating system
Provides a low-level interface
Library operating systems offer portability and compatibility
The benefits of the exokernel operating system include:

Improved performance of applications
More efficient use of hardware resources through precise resource allocation and revocation
Easier development and testing of new operating systems
Each user-space application is allowed to apply its own optimized memory management.

Microkernel is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system (OS). These mechanisms include low-level address space management, thread management, and inter-process communication (IPC).

If the hardware provides multiple rings or CPU modes, the microkernel may be the only software executing at the most privileged level, which is generally referred to as supervisor or kernel mode. Traditional operating system functions, such as device drivers, protocol stacks and file systems, are typically removed from the microkernel itself and are instead run in user space.

It has been shown in the meantime that user-level device drivers can come close to the performance of in-kernel drivers even for such high-throughput, high-interrupt devices as Gigabit Ethernet. This seems to imply that high-performance multi-server systems are possible.