Chapter 3 Flashcards
Chapter 3 delves into virtualization, a core technology underpinning cloud computing (8 cards)
Concept of Virtualization
A core technology creating an abstraction layer between computing resources and the software that uses them.
Enables multiple virtual environments (VMs, containers, etc.) to run on a single physical system.
Allows multiple operating systems and applications to run on a single computer/server.
Can be applied across servers, networks, storage, desktops.
Driven by the hypervisor.
Function of a Hypervisor
Also known as a Virtual Machine Monitor (VMM).
Critical software/firmware that manages and controls virtual machines running on a physical system.
Allocates resources like CPU, memory, storage to VMs.
Ensures each VM operates independently, securely, and efficiently.
Ensures isolation of VMs to prevent security vulnerabilities.
Provides functionalities like resource management, hardware emulation, live migration, snapshot creation.
Types of Hypervisors
Type 1 (Bare-Metal Hypervisors): Run directly on the physical hardware without an underlying OS. Offer high performance, commonly used in data centers. Examples: VMware ESXi, Microsoft Hyper-V, KVM, Xen.
Type 2 (Hosted Hypervisors): Run on top of an existing operating system (the host OS). Rely on the host OS for hardware access. More suitable for desktop environments, development, personal use. Examples: Oracle VirtualBox, VMware Workstation, Parallels Desktop.
Benefits of Virtualization
Efficient Resource Utilization: Abstracts physical resources, enabling multiple OS on a single server simultaneously, significantly improving utilization. Minimizes wasted power, optimizes workload distribution.
Lower Costs and Extended Life of Technology: Reduces hardware needs, power consumption, maintenance, and rack space. Extends the life of existing hardware.
Enhanced Security: Provides isolation between VMs, preventing one system/program from affecting others. Supports better access control and fault tolerance.
Reduction in Terminal Equipment and Simplified Administration: Reduces need for physical hardware (workstations, servers, networking). Simplifies IT infrastructure management and lowers maintenance costs. Automated tools streamline administration.
Dynamic Data Center and Improved Availability: Supports dynamic sharing of physical resources, enabling efficient load balancing and real-time scaling. Centralized management tools optimize resources.
Promotes Green Computing by reducing energy consumption.
Disadvantages of Virtualization
High Cost of Implementation: Significant initial investment in powerful hardware, software, licensing, storage, networking. Also requires investment in training.
Requires High-End and Powerful Infrastructure: Needs high-performance servers, advanced storage, reliable networks. Running multiple VMs needs powerful processors, RAM, high-speed storage.
Potential Security Risks: Although isolation helps, shared underlying resources can introduce risks if not managed properly.
Requires a Specialized Skill Set to manage.
May lead to Lower Performance if infrastructure is inadequate. (Note: Source mentions binary translation in Full Virtualization affecting performance, but this disadvantage specifically applies to one approach within hardware virtualization).
Virtualization Approaches/Types
Different approaches exist for different workload requirements.
Main types discussed: Full Virtualization, Paravirtualization, OS-Level Virtualization (Containerization). (Note: Source asks to explain three approaches). The source also lists different types of virtualization based on the resource being virtualized.
Specific Types of Virtualization (by resource)
Server virtualization: Dividing a single physical server into multiple virtual servers, each with its own OS/applications. Achieved via a hypervisor. Improves resource utilization, reduces costs, simplifies management, enhances security.
Operating System (OS) virtualization (Containerization): Running virtualization software on a pre-existing host OS. Allows multiple isolated instances (containers) to run on a single OS kernel. Containers share the host kernel. Provides less isolation than VMs but offers low overhead and fast startup. Efficient in resource usage as containers share the host OS kernel. Key for cloud-native environments, microservices. Examples: Docker, Kubernetes, LXC.
Memory virtualization: Abstracting physical memory and managing it across multiple VMs or applications. Ensures each VM appears to have dedicated memory while sharing physical memory. Managed by the hypervisor. Concepts include Page Table, Memory Overcommitment, Ballooning, Transparent Page Sharing, Swap/Paging.
Storage virtualization: Abstracting and pooling storage resources from multiple physical devices into a single logical unit. Managed as one resource regardless of underlying devices. Improves resource utilization, simplifies management, enhances scalability. Types: Block-Level (SANs, high performance, data centers), File-Level (NAS, managing unstructured data), Unified Storage (combines block and file).
Application virtualization: Abstracting applications from the underlying OS to run in a virtual environment. Allows application access without local installation. Can improve compatibility and simplify deployment. Types: Streaming, Local, Remote Desktop Services (RDS), via Hypervisors [156, not fully detailed in sources].
Hardware virtualization: Allows multiple OS/VMs to run on a single physical machine by sharing underlying hardware resources. Uses a hypervisor (VMM) to create/manage VMs, abstract hardware, allocate resources. Provides isolation between VMs. Key benefits: flexibility, resource optimization, isolation. Works by abstracting physical hardware (virtual CPUs, memory, etc.) and presenting a virtualized version to guest VMs.
Multitenant Technology
A software architecture where a single instance of an application serves multiple tenants (customers).
Maintains data isolation and independent configurations for each tenant.
Fundamental to cloud computing and SaaS.
Offers cost savings, efficient resource utilization, faster scaling.
Advantages: (Same as characteristics listed under Cloud Enabling Technologies) Usage Isolation, Data Security, Scalability & Upgrades, Metered Usage, Data Tier Isolation, Cost savings, Efficient resource utilization, Faster scaling.
Disadvantages: (Not explicitly detailed in the provided text excerpts for this specific concept heading, but general disadvantages of multi-tenancy could include increased complexity, security risks related to shared infrastructure, noisy neighbor issues - although the text claims security measures mitigate this). Source lists “Increased operational and infrastructural costs and people’s skills” and “Service delivery” as potential disadvantages, which seem to contradict some benefits or imply challenges in implementation rather than the technology itself.
