Virtualization Concepts and Cloud Computing

Course Objectives

• Understand machine virtualization and its relevance to cloud computing
• Explore paravirtualization, hardware support, and their impact on performance and security
• Describe features and services offered by IaaS platforms in public and private clouds
• Connect IaaS services to the functions and roles of a traditional operating system

Introduction

• Virtualization abstracts resources from physical resources presented to users and applications.
• Cloud computing enables decoupled management of virtual cloud servers (IaaS, PaaS, SaaS) and the physical machines supporting them.
• Key advantages include cost-efficiency, flexibility (unified OS/app management), isolation, dependability, and performance improvements.

Outline

• Basics of OS-level virtualization
• Principles of platform virtualization
• Requirements for cloud computing
• Virtualization implementation (OS support, hardware support, performance, and portability)
• Desktop virtualization

Basics: OS-Level Virtualization

• A single operating system (OS) supports multiple processes and applications.
• Processes cannot freely access system resources.
• Virtualization is needed to manage resource allocation among processes.
• OS implements policies for resource arbitration.

Example 1: Virtual Memory

• Each process has its own address space, isolating it from others.
• The OS maps virtual addresses to physical addresses(memory).
• Built-in hardware support (e.g., MMU, TLB) is essential for efficient implementation.

Example 2: Virtual CPU

• Each thread assumes it handles CPU operations.
• Context switching is crucial to manage and schedule threads.
• Hardware support (e.g., process-aware TLB) enhances virtual CPU functionality.

Platform Virtualization

• A single physical computer can support multiple virtual computers sharing resources between multiple operating systems and applications.

A Key Enabling Technology for Cloud Computing

• Virtualized servers outnumber non-virtualized ones (2014 data).
• Advantages for users include resource abstraction, isolation, pay-as-you-go deployments, and instance migration.
• Advantages for cloud operators include reduced operational costs, larger efficient server capabilities, and increased operational flexibility (migration, consolidation, etc.).
• Disadvantages may include costs associated with multiple OS versions, and performance penalties.

Virtualization Implementation

• Modern OS isolation depends on multiple instruction modes.
• Non-privileged instructions, like mathematical operations, typically operate without interruption,.
• Privileged instructions require kernel-level access, typically for critical operations like process termination

Virtualization Requirements

• CPU instructions are classified as privileged or sensitive instructions, affecting virtual machine management.
• Required properties include equivalence (same output as raw hardware), resource control, and efficiency.
• Effective virtual machine management (VMM) construction can be achieved when sensitive instructions are a subset of privileged instructions,.

x86 and Virtualization

• Initially (around 2010 when cloud computing gained interest), x86 architecture for desktops and servers and used 32 bits.
• Commercial interest in virtualization was significant.
• However, original x86 32 bits architecture was not designed with virtualization in mind .
• More complex x86-32 architectures include a large number of sensitive instructions.
• Modern processors directly support virtualization with hardware-assisted virtualization.

Server Virtualization Approaches

• Three generations of server virtualization exist
• First generation: Binary Rewriting (software-based full virtualization).
• Second generation: Paravirtualization (software-based collaborative virtualization).
• Third generation: Hardware-assisted full virtualization (hybrid approach combining software and hardware).

First Generation Virtualization

• An emulation layer exists in the host operational system, enabling the emulation of all hardware components including the CPU.
• Binary rewriting translates instructions on the fly.
• The guest OS is unaware it is running on an emulated environment .
• Tools, like QEMU, support this type of virtualization.

First Generation Virtualization (Advantages and Disadvantages)

• Significant advantages include good VM isolation, precise VM resource control, and total transferability.
• However, significant disadvantages are significant performance penalties.
• VMs cannot use hardware instructions directly and require emulation.

Second Generation Virtualization (Paravirtualization)

• The guest OS is modified so it does not need to use privileged instructions itself.
• It correctly interfaces with the hypervisor to handle privileged operations.
• Paravirtualization dramatically improves performance.

Second Generation Virtualization (Advantages & Disadvantages)

• Optimized performance.
• Requires modified OS, which is a limitation.

Third Generation Virtualization

• Hardware support exists for virtualization.
• Guests can use privileged instructions without intervention from the hypervisor, resulting in high performance.
• However, it is important for OS to recognize virtualization.

Some Common Virtualization Solutions

• VirtualBox (full and hybrid virtualization with hardware support)
• KVM (full and hybrid virtualization with hardware support, utilizing virtio for I/O device drivers)
• VMware (full range of virtualization types).

Virtualization and Security

• Hypervisor-based rootkits can exploit vulnerabilities in a non-virtual system and exploit hardware-assisted virtualization.
• Collocation attacks leverage security flaws in the hypervisor

Desktop Virtualization

• Run a guest operating system within the host operating system.
• Less stringent performance requirements.
• Often use paravirtualization to efficiently share resources like network cards and other devices.

VM Images and Operations

• Disk images (read/write and read-only) are used for VMs.
• Common formats include VHD, VDI, QCOW2, and ISO.
• VM imports/exports use OVF, OVA, and AMI formats..
• VMs can be migrated between environments.

Part II - IaaS Management

• IaaS is a model for renting cloud infrastructure resources.
• IaaS allows users to manage their own operating systems and environments.

Key Players in the Public Cloud IaaS Market

• Amazon Web Services
• Microsoft Azure
• HP
• Google Compute Engine
• Rackspace Open Cloud
• IBM SmartCloud

Public Cloud IaaS Operations

• Dynamically allocate resources like VMs.
• Deploying a VM image to a host from an image.
• Migrate a VM between hosts, modifying required resource amounts dynamically.
• Manage access keys (e.g., SSH).

Defining Needs: Instances

• Users configure VMs' computational capacity (VCPU, memory) and storage types (remote or dedicated).
• Example configuration from Rackspace includes General purpose, Compute optimized, I/O optimized, and Memory optimized.

Typical laaS Pricing

• Pricing varies by provider and instance type.
• Factors like storage, network bandwidth, operating system type, and location can affect pricing.

Spot Instances Mechanics

• Best-effort instances with low cost.
• Used by IaaS providers to maximize infrastructure utilization and offer competitive pricing on unused machines.
• Pricing is based on a bidding/offering mechanism.
• The market adapts to the current demand

Example of Use

• Resizing photos and complex tasks like video encoding are typically more expensive if used on general and regular VMs due to ongoing use of infrastructure.
• Utilization of a cloud environment is beneficial when these type of applications require significant computation capacity.

Bitmovin Example

• Re-encoding HD video requires high processing power.
• Utilizing spot instances reduces costs.

laaS Management: The "Cloud Operating Systems"

• Cloud operating systems manage the fleet of hosts, virtual machines, and resources.
• Operations such as allocation, monitoring (usage, faults), and billing are performed by a IaaS management system.

An Operating System Analogy

• laaS management platforms are analogous to operating systems, managing resources and handling VM(s) instead of processes and applications, and managing inter-VM networking.

Direct Infrastructure Access

• Direct infrastructure access allows users to access and interact with infrastructure without mediation via hypervisor.

laaS Management Platform

• laaS platforms manage the host(s), monitor resources, allocate resources to VMs.
• A command line or web interface is typically used for management.

Advantages of Using an laaS Management System

• Unified management and control is possible allowing centralized management/control of numerous servers.
• Better resource allocation due to centralized control and monitoring allowing better utilization.
• Improved security due to enhanced authentication, and access control. Increased reusability if VM images are stored and deployable by multiple users across environments.

OpenStack

• Large open-source project.
• Driven by Rackspace and a large community of companies offering cloud-based solutions.
• Meeting the requirements of large scale public and private clouds with high scalability.

Conclusion

• Virtualization is crucial for economies of scale and efficiency in cloud computing, enabling easy management, allocation, and monitoring of IaaS resources.
• Public cloud IaaS offers on-demand renting of infrastructure (VMs, networks, and storage).
• Private and hybrid clouds similarly make use of operating systems software on physical hosts or on VMs, allowing management, authentication, and monitoring functionalities.

Test your knowledge on the key concepts of virtualization and its impact on cloud computing. This quiz covers paravirtualization, hypervisor security, and the role of operating systems in virtualization. Enhance your understanding of how virtualization benefits cloud infrastructures.