Module: Virtual Layer

Upon completion of this module, you should be able to:

• Describe the virtual layer and virtualization software
• Describe a resource pool and virtual resources

Module: Virtual Layer

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 Cloud Computing Reference Model
Virtual Layer

Module: Virtual Layer

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 Lesson: Virtual Layer Overview
This lesson covers the following topics:
• Virtual layer
• Virtualization software
• Resource pool
• Virtual resources

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Introduction to Virtualization
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 or multiple hardware resources to
support single instance of system.

• Enables a resource to appear larger or smaller than it actually is

• Enables a multitenant environment improving utilization of
physical resources

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Benefits of Virtualization
• Optimizes utilization of IT resources
• Reduces cost and management complexity
• Reduces deployment time
• Increases flexibility

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Virtual Layer Overview
• Virtualized compute, network, and storage forms the virtual
layer
• Enables fulfilling two characteristics of cloud infrastructure
– Resource pooling
– Rapid elasticity
• Specifies the entities operating at this layer
– Virtualization software
– Resource pools
– Virtual resources

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 Virtual Layer
Virtualization Process and Operations

Step 1: Deploy Step 2: Create resource Step 3: Create virtual Virtual

virtualization software pools: resources: resources are
on: • Processing power and • Virtual machines
packaged and
• Compute systems memory • Virtual networks
• Network devices • Network bandwidth
offered as
• LUNs
• Storage devices • Storage services

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Compute Virtualization Software
Hypervisor

Hypervisor

Software that is installed on a compute system and enables multiple OSs to

run concurrently on a physical compute system.

• Hypervisor kernel
– Provides functionality similar to an OS kernel
– Designed to run multiple VMs concurrently

• Virtual machine manager (VMM) VMM VMM

– Abstracts hardware Hypervisor Kernel
– Each VM is assigned a VMM
– Each VMM gets a share of physical resources

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Compute Virtualization Software (Cont'd)
Types of Hypervisor

Bare-metal Hypervisor Hosted Hypervisor

• It is an operating system • Installed as an application on an
OS
• Installed on a bare-metal
hardware • Relies on OS, running on
physical machine for device
• Requires certified hardware
support
• Suitable for enterprise data
• Suitable for development,
centers and cloud infrastructure
testing, and training purposes

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Network Virtualization Software
• Abstracts physical network resources to create virtual
resources:
– Virtual LAN/virtual SAN
– Virtual Switch
• Network virtualization software can be:
– Built into the operating environment of a network device
– Installed on an independent compute system
• Fundamental component for deploying software defined network
– Hypervisor’s capability

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Storage Virtualization Software
• Abstracts physical storage resources to create virtual
resources:
– Virtual volumes
– Virtual disk files
– Virtual arrays
• Storage virtualization software can be:
– Built into the operating environment of a storage device
– Installed on an independent compute system
• Fundamental component for deploying software defined storage
– Hypervisor’s capability

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 Lesson Summary
During this lesson the following topics were covered:
• Virtual layer
• Virtualization software
• Resource pool
• Virtual resources

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 Lesson: Resource Pool
This lesson covers the following topics:
• Resource pool
• Examples of resource pooling
• Identity pool

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Introduction to Resource Pool
Resource Pool
A logical abstraction of the aggregated computing resources, such as
processing power, memory capacity, storage, and network bandwidth that
are managed collectively.
• Cloud services obtain computing resources from resource pools
– Resources are dynamically allocated as per consumer demand

• Resource pools are sized according to service requirements

Resources for Aggregation Service A
Consumer A

Resource Allocation

Consumer B
Resource Pool
Service B

Cloud Infrastructure

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Example: Pooling Processing Power and
Memory Capacity Assigned to
Consumer A

Resource Allocation Processing power = 1500 MHz

Memory Capacity = 2 GB

Compute System 1 Resource Allocation Processing power = 1500 MHz

Processing Power = 4000 MHz Memory Capacity = 2 GB
Memory Capacity = 6 GB

Service A

Service B
Compute System 2
Processing Power = 4000 MHz Resource Allocation Processing power = 1500 MHz
Memory Capacity = 6 GB Memory Capacity = 2 GB

Resource Allocation Processing power = 1500 MHz

Memory Capacity = 2 GB
Compute System 3
Processing Power = 4000 MHz Resource Allocation Processing power = 1500 MHz
Memory Capacity = 6 GB
Memory Capacity = 2 GB
Processor Pool: Processing Power = 12000 MHz
Memory Pool: Memory Capacity = 18 GB
Assigned to
Consumer B

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Example: Pooling Storage in a Block-based
Storage System
Block-based Storage System

Service A

Resource Allocation
Assigned to
Consumer A
Drive 1 LUN
Storage Space = Storage Space = 200 GB
1000 GB

Service B
Drive 2
Storage Space = Resource Allocation
1000 GB
Assigned to
Consumer B
LUN
Storage Space = 400 GB
Drive 3
Storage Space
= 1000 GB Service C

Resource Allocation
Assigned to
Drive 4 Consumer C
Storage Space =
LUN
1000 GB
Storage Space = 800 GB

Storage Pool: Storage Space = 4000 GB

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Example: Pooling Storage Across Block-based
Storage Systems
Assigned to Assigned to Assigned to
Consumer A Consumer B Consumer C

Service A Service B Service C

LUN LUN LUN

Block-based Block-based Block-based Block-based

Storage System Storage System Storage System Storage System

Storage Storage
Pool Pool

Higher-level Storage Pool

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Example: Pooling Network Bandwidth of NICs
Service A Service B

Assigned to Assigned to
Consumer A Consumer B

Resource Allocation

Bandwidth = 600 Mbps Bandwidth = 300 Mbps

Compute System

NIC 1 NIC 2 NIC 3

Bandwidth = Bandwidth = Bandwidth =
1000 Mbps 1000 Mbps 1000 Mbps

Network Bandwidth Pool: Bandwidth = 3000 Mbps

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Identity Pool
• Specifies a range of network identifiers (IDs) such as virtual network
IDs and MAC addresses
– IDs are allocated from the identity pools to the elements of cloud services

• An identity pool may map to a particular service or to a group of

services
Service A

ID Allocation Assigned to
ID Range: 1 to 10 Consumer A

Identity Pool A
Service B

ID Allocation Assigned to
ID Range: 11 to 100 Consumer B

Identity Pool B

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 Lesson Summary
During this lesson the following topics were covered:
• Resource pool
• Examples of resource pooling
• Identity pool

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 Lesson: Virtual Resources – I
This lesson covers the following topics:
• Virtual machine (VM) and VM hardware
• VM files and file system to manage VM files
• VM console
• VM template
• Virtual appliance
• VM network and its components

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Virtual Machine (VM)
Virtual Machine

A logical compute system that, like a physical compute system, runs an OS

and applications.

• Created by a hypervisor installed on a physical compute system

• Comprises virtual hardware, such as virtual processor,
memory, storage, and network resources
– Appears as a physical compute system to the guest OS
– Hypervisor maps the virtual hardware to the physical hardware
• Provider provisions VMs to consumers for deploying
applications
– VMs on the same compute system or cluster run in isolation
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VM Hardware

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VM Files
• From a hypervisor’s perspective, a VM is a discrete set of files
such as:
• Stores information, such as VM name, BIOS
Configuration file information, guest OS type, memory size

Virtual disk file • Stores the contents of the VM's disk drive

• Stores the memory contents of a VM in a suspended

Memory state file state

Snapshot file • Stores the VM settings and virtual disk of a VM

• Keeps a log of the VM’s activity and is used in

Log file troubleshooting

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File System to Manage VM Files
• Hypervisor’s native file system
– Clustered file system deployed on local or
external storage
– Enables multiple hypervisors to perform
concurrent reads and writes
– Enables high availability to protect against
hypervisor or compute system failure
• Shared file system
– Enables storing VM files on remote file
servers or NAS devices
– Hypervisors have built-in NFS or CIFS clients

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VM Console
• VM console is an interface to view and manage the VMs on a
compute system or a cluster
• VM console may be:
– Installed locally on a compute system
– Web-based
– Accessed over a remote desktop connection
• Used to perform activities such as:
– Installing a guest OS and accessing VM BIOS
– Powering a VM on or off
– Configuring virtual hardware and troubleshooting

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VM Template
VM Template

A master copy of a VM with standardized virtual hardware and software

configuration that is used to create new VMs

• Created in two ways:

– Converting a VM into a template
– Cloning a VM to a template
• Steps involved in updating a VM template are:
1. Convert the template into VM
2. Install new software or OS/software patches
3. Convert the VM back to a template

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Virtual Appliance
Virtual Appliance

Preconfigured virtual machine(s) preinstalled with a guest OS and an

application dedicated to a specific function.

• Used for functions, such as providing SaaS, routing packets, or

deploying a firewall
• Simplifies the delivery and operation of an application
– Simplifies installation and eliminates configuration issues
– The application is protected from issues in other virtual appliances
• Typically created using Open Virtualization Format (OVF)

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VM Network
VM Network

A logical network that provides Ethernet connectivity and enables

communication between VMs within a compute system.

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VM Network Components
Component Description

Virtual switch • A logical OSI Layer 2 Ethernet switch created in a compute system
• Connects VMs locally and also directs VM traffic to a physical network
• Forwards frames to a virtual switch port based on destination address
• A distributed virtual switch can function across multiple physical
compute systems
Virtual NIC • Connects a VM to a virtual switch and functions like a physical NIC
• Has unique MAC and IP addresses
• Forwards the VM’s network I/O in the form of Ethernet frames to the
virtual switch
Uplink NIC • A physical NIC connected to the uplink port of a virtual switch
• Functions as an ISL between virtual and physical Ethernet switches
• Not addressable from the network

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 Lesson Summary
During this lesson the following topics were covered:
• Virtual machine and VM hardware
• VM files and file system to manage VM files
• VM console
• VM template
• Virtual appliance
• VM network and its components

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 Lesson: Virtual Resources – II
This lesson covers the following topics:
• Logical unit number (LUN)
• Creating LUN from RAID set
• Creating LUN from storage pool

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Logical Unit Number (LUN)
Logical Unit Number (LUN)

Abstracts the identity and internal functions of storage system(s) and

appear as physical storage to the compute system.
• Mapping of virtual to physical storage is performed by the
virtualization layer.
• Provider provisions LUN to consumers for storing data
– Storage capacity of a LUN can be dynamically expanded or reduced

• LUN can be created from

– RAID set (traditional approach)
– Storage pool

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Creating LUNs from RAID Set
• LUNs are created from a RAID set by partitioning the available
capacity into smaller units
– Spread across all the physical disks that belong to a RAID set
• Suited for applications that require predictable performance

Compute
Virtual
Volume 0 System 1

Compute
Virtual System 2
Volume 1

RAID Set

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Creating LUNs from Storage Pool
• Two types of volumes are created from Thin LUN
(10 TB)

storage pool: Thick

LUN

– Thin LUN Compute

Reported
Capacity Compute
4 TB
4 TB Reported
• Does not require physical storage to be Allocated
Allocated
Capacity

completely allocated at the time of creation

• Consumes storage as needed from the
underlying storage pool in increments called
thin LUN extents
– Thick LUN Disk Drives
• Physical storage is completely allocated at the
time of creation Storage Pool

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Use of Thin LUN
• Thin LUNs are appropriate for applications that can tolerate
performance variations
– In some cases, performance improvement is seen when using a
thin volume due to striping across large number of drives in the
pool
• Environments where cost, storage utilization, space, and
energy efficiency is paramount
• For applications where storage space consumption is difficult to
forecast
• Environment that needs optimized self provisioning

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 Lesson Summary
During this lesson the following topics were covered:
• LUN
• Creating LUN from RAID set
• Creating LUN from storage pool

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 Lesson: Virtual Resources – III
This lesson covers the following topics:
• Virtual network
• Types of virtual networks: VLAN and VSAN
• Mapping between VLANs and VSANs in an FCoE SAN

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Virtual Network
Virtual Network

A software-based logical network that is either a segment of a physical

network or spans across multiple physical networks.

• Appears as a physical network to the connected nodes

• Virtual networks share network components without leaking
information between them
• Network traffic is routed only when two nodes in different virtual
networks are communicating
• All types of networks can be virtualized, such as compute network,
SAN, and VM network

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Virtual Network Example

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Common Types of Virtual Networks
• Virtual LAN (VLAN)
• Private VLAN (PVLAN)
• Stretched VLAN
• Virtual extensible LAN (VXLAN)
• Virtual SAN (VSAN)

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Virtual LAN (VLAN)
Virtual LAN (VLAN)

A virtual network created on a LAN enabling communication between a

group of nodes with a common set of functional requirements, independent
of their physical location in the network.

• A VLAN is identified by a unique 12-bit VLAN ID

• Configuring a VLAN:
– Define VLAN on physical and virtual switches and assign VLAN ID
– Configure VLAN membership based on port, MAC address,
protocol, IP subnet address, or application

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Private VLAN (PVLAN)
Private VLAN

A sub-VLAN that segregates the nodes within a standard VLAN, called as

primary VLAN. A PVLAN can be configured as either isolated or community.

• Enables a provider to support a

larger number of consumers
• Provides security between
nodes on the same VLAN
• Simplifies network
management

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Stretched VLAN
Stretched VLAN

A VLAN that spans multiple sites and enables Layer 2 communication

between a group of nodes over a Layer 3 WAN infrastructure, independent
of their physical location.

• Layer 2 WAN frames are

encapsulated in Layer 3
WAN packets
• Enables movement of VMs
across locations without
changing their network
configuration

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Virtual Extensible LAN (VXLAN)
Virtual Extensible LAN

A logical Layer 2 overlay network built on a Layer 3 network, which uses

MAC-in-UDP encapsulation to enable communication between a group of
nodes, independent of their physical location.

• VXLAN header is added to a Layer 2 frame, which is placed in a UDP-IP

packet and tunneled over a Layer 3 network
– Enables transparent Layer 2 communication between nodes over physical
networks spanning Layer 3 boundaries
– Encapsulation and decapsulation are performed by Virtual Tunnel
Endpoints (VTEPs)

• 24-bit VXLAN ID provides up to 16 million VXLANs

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Virtual SAN (VSAN)
Virtual SAN

A logical fabric, created on a physical FC or FCoE SAN enabling

communication between a group of nodes with a common set of
requirements, independent of their physical location in the fabric.

• A VSAN has its own fabric services, configuration, and set of FC

addresses
• Traffic disruptions in one VSAN do not affect other VSANs
• A VSAN may be extended across sites similar to a stretched
VLAN

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Virtual SAN (VSAN) (Cont'd)
• Configuring VSAN:
– Define VSANs on fabric switch with
specific VSAN IDs
– Assign VSAN IDs to F_Ports to include
them in the VSANs
• An N_Port connecting to an F_Port in a
VSAN becomes a member of that VSAN

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Mapping VLANs and VSANs in an FCoE SAN
• Mapping determines which VLAN carries a VSAN traffic
• Mapping considerations:
– Configure a dedicated VLAN for each VSAN
– VLANs configured for VSANs should not carry regular LAN traffic

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 Lesson Summary
During this lesson the following topics were covered:
• Virtual network
• Types of virtual network: VLAN, private VLAN, stretched
VLAN, VXLAN, and VSAN
• Mapping between VLANs and VSANs in an FCoE SAN

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 Concepts in Practice
• VMware ESXi

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VMware ESXi

ESXi
• Bare-metal hypervisor

• Abstracts processor, memory, storage, and network resources

into multiple VMs
• Comprises underlying VMkernel OS that supports running
multiple VMs
- VMkernel controls and manages compute resources

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 Module Summary
Key points covered in this module:
• Virtual layer
• Virtualization software
• Resource pool
• Virtual resources

Module: Virtual Layer

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