The provided text is a continuation of the Cloud Computing topic, focusing on Virtualization Types, Server Virtualization Benefits/Limitations, and Network Virtualization. This information is essential for understanding cloud infrastructure.
Here is a summary of the concepts from the image:
1. Types of Virtualization
The text highlights two main types of virtualization techniques beyond the base concept:
Para-Virtualization:
In this model, simulation overhead is reduced because the guest operating system (OS) is modified to communicate directly with the Hypervisor (the virtualization software).
This modification improves overall performance compared to Full Virtualization.
Full Virtualization:
This model fully emulates the underlying hardware. It is more complex than Para-Virtualization.
The guest operating system is unmodified and runs directly on top of the hypervisor.
The hypervisor intercepts and manages machine operations (like I/O) and returns the status codes, making it seem like the guest OS is running on physical hardware.
2. Benefits and Limitations of Server Virtualization
Benefits of Server Virtualization
Cost Reduction: Reduces hardware requirements, which leads to lower costs.
Isolation: Each virtual server can be rebooted independently without affecting the operation of other virtual servers on the same physical machine.
Consolidation: Supports live migration and server consolidation, maximizing hardware usage.
Disaster Recovery: Facilitates easier backup and recovery from disasters.
Simplified Maintenance: Makes it easier to install or set up software patches and updates.
Limitations of Server Virtualization
Availability and Resource Consumption: Potential issues with resource consumption and guaranteed availability due to overcommits (allocating more virtual resources than physical resources exist).
Upfront Costs: Significant initial costs related to the virtualization software and network setup.
Licensing: Complexity and cost associated with software licensing for the virtual environments.
Steep Learning Curve: IT staff requires specialized training and experience in virtualization management.
Security: Security can be a concern, especially if multiple virtual servers belonging to different tenants or functions share the same physical server.
3. Network Virtualization
Network Virtualization (NetV) is the core technology that builds the connectivity fabric for cloud storage and computing.
Concept: It's similar to Server Virtualization but applies to the network. Instead of dividing a physical server, network resources (bandwidth, channels, switches, etc.) are divided among multiple virtual networks.
Purpose: It is used in multi-tenant data centers where each tenant needs its own isolated virtual network.
How it Works (Tunneling): A common way to isolate virtual networks is by providing a special label within each data frame that identifies the virtual network it belongs to. This labeling and forwarding is called network tunneling.
Definition: The method of splitting up network resources into separate bandwidth channels that are isolated and independent of one another, which can then be assigned and reassigned to different services or servers.
Goal: To optimize the speed, reliability, and flexibility of the network.
Types of Network Virtualization
External Network Virtualization:
Combines multiple networks or parts of networks into a single virtual unit.
A key goal is to improve the efficiency of a large network/data center.
Its two main components are the Virtual Local Area Network (VLAN) and the network switch.
System administrators use these to configure systems that are physically attached to the same local network into many different virtual networks.
1. Internal Virtualization
Internal virtualization (also called network in a box) uses software containers to mimic or provide the functionality of a single physical machine.
It's a network virtualization confined to a single system.
It improves the overall efficiency of a single system by isolating the separate virtual environments and allowing them to communicate over a virtual network interface.
This type is commonly seen on workstation versions of VMware and similar platforms.
2. Basic Components of Virtual Networks
Virtual networks have three fundamental components:
Network hardware: Includes network interface cards, virtual switches, and VLANs.
Network storage devices: The devices where the data is actually stored.
Network media: The physical cabling used, usually Ethernet or Fiber Channel.
3. Architecture of Network Virtualization
As illustrated in Fig. 3.5: Network Virtualization, multiple virtual networks run on a single physical network.
Process: Network virtualization comprises rationally grouping and segmenting physical network(s) into distinct rational units known as 'virtual network(s)' and forming them to act as one or multiple separate networks.
Resource Sharing: It allows multiple virtual networks to share the underlying physical network resources (routers, hubs, switches, etc.) within the Virtual Data Center (VDC).
VM Network: A virtual network exists entirely within a physical server where the Hypervisor runs the host machine, and each virtual machine is considered a guest machine.
Goal: It allows the construction of multiple virtual networks in the Data Center (DC) while ensuring all nodes belonging to a single working unit in an enterprise are aligned.
4. Benefits of Network Virtualization
Reduced Hardware and Power Consumption: Network virtualization reduces the amount of physical network hardware required, leading to a corresponding decrease in power consumption in the office space.
Automated Management: It allows for the easy and automatic administration of network security and protocols, ensuring they are consistently applied across the entire virtualized network infrastructure.
Simplified Provisioning and Troubleshooting:
Network Provisioning (the delivery of new services to network users) is greatly simplified in a virtual environment.
Troubleshooting is also easier because the management and control of the entire virtual network are consolidated in a single physical location.
Improved Scalability:
Network virtualization provides a quick and easily scalable solution.
It removes the IT infrastructure as a major barrier to business growth, allowing organizations to respond to market demands with agility.
Disadvantages of Network Virtualization
While powerful, Network Virtualization has several limitations that an organization must consider:
Increased Upfront Costs: There is a significant initial cost associated with investing in virtualization software.
Need to License Software: Organizations must deal with the complexity and cost of licensing the virtualization software.
Steep Learning Curve: There may be a substantial learning curve if IT managers and staff are not already experienced in virtualization technology.
Application Incompatibility: Not every application and server is guaranteed to work flawlessly in a virtualized environment. Compatibility issues can arise.
Availability Issues: Availability (the ability to access the data) can be a critical issue if an organization faces network problems and cannot connect to its virtualized data, highlighting the dependency on network connectivity.
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