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+#let title = [
+  Unit 4: Virtual Layer
+]
+#let proverb = [
+  Knowledge not shared, remains unknown.
+]
+#set text(12pt)
+#set page(
+  header: [ 
+    #box()[#proverb]
+    #h(1fr)
+    #box()[#title]
+    ],
+)
+#align(center, text(20pt)[
+  *#title*
+])
+
+#show table.cell.where(y: 0): strong
+
+= Basics
+- Deployed on the physical layer.
+- Specifies entities like virtualization software, resource poolsm and virtual resources.
+- Abstracts the physical resources (compute, storage, network).
+- Executing requests from control layer and forwarding them to the physical layer for execution.
+= Introduction
+_*Virtualization refers to the logical abstraction of physical resources such as compute, network and storage that enables a single hardware resource to support multiple concurrent instances of systems ot multiple hardware resources to support single instance of system.*_
+- Allows us to make resources look larger or smaller than they actually are.
+- Enables multitenant environment improving utilization of physical resources.
+= Benefits of virtualization
+1. Optimizes and consolidates utilization of IT resources.
+2. Reduces cost and management complexity.
+3. Reduces number of people required to maintain the system.
+4. Reduces deployment time.
+5. Increases flexibility.
+= Overview
+This layer is formed from virtualized compute, virtualized network, and virtualized storage. This enables 2 characteristics of cloud software: 
+1. Resource Pooling
+2. Rapid elasticity
+This layer also specifies the entities that operate in this layer:
+1. Virtualization software
+2. Resource Pools
+3. Virtual resources 
+= Process and Operations
+The key steps involved in making resources available to comsumers are:
+1. Deploying virtualization software.
+  - Compute systems.
+  - Network devices.
+  - Storage devices.
+2. Creating resource pools.
+  - Processing power and memory
+  - Network bandwidth
+  - Storage
+3. Creating virtual resources.
+  - Virtual machines
+  - Virtual Networks
+  - LUNs
+== Virtualization Software
+The virtualization software performs the abstraction of the physical resources that ard deployed on computer systems, network devices, and storage devices.\
+The key functions of virtualization software is:
+1. Create resource pools
+2. Create virtual resources.
+== Resource Pools
+A resource pool is an aggregation of computing resources such as processing power, memory, storage, and network bandwidth which provices an aggregated view of these resources to the control layer.
+== Virtual resources
+Virtualization software in collaboration with control layer creates virtual resources. Created by allocating physical resources from the resource pool. Share the pooled physical resources.
+= Hypervisor
+_*Hypervisor is a piece of software that is installed on a compute system and enables multiple OSs to run concurrently on a physical compute system.*_\
+- The hypervisor along with the hypervisor management software (HMS) is the fundamental component for deploying software defined compute environments.\
+- Abstracts the physical compute hardware to create multiple *virtual machines*.\
+- The hypervisor provides standardized hardware resources, such as processor, memory, network, and disk to all virtual machines.\
+Hypervisor has two main components:
+1. Kernel
+  - Acts as kernel of any normal OS.
+  - Performs process creation, file system management, and process scheduling.
+  - Optimized for running multiple VMs concurrently.
+2. Virtual Machine Manager (VMM)
+  - Anstracts hardware and appears as a physical compute system with all components required for running OSs and applications.
+  - Each VM is assigned a VMM that gets a share of the physical resources.
+
+#pagebreak()
+
+== Types of hypervisors
+Categorized into two types:
+#table(
+  columns: 2,
+  table.header[Bare Metal Hypervisor][Hosted Hypervisor],
+  [Installed directly on hardware.], [Installed as an application on host system.],
+  [Direct access to hardware resources.], [No direct access. All access through host OS.],
+  [More efficient.], [Less efficient.],
+  [Limited device drivers.], [Compatible with all devices supported by host OS.],
+  [Designed for data centers and cloud infrastructure.], [Used for development, testing and training.],
+)
+