Role of Hypervisor in Cloud Computing Prof Bharati

Role of Hypervisor in Cloud Computing Prof. Bharati Ainapure

Outline Ø Server Virtualization ØThe Virtual Server Concept ØHypervisors And Hosts ØHypervisors and Virtual Machines ØTypes of hypervisor ØVirtualization techniques ØBenefits and Features

Server Virtualization Before Server Virtualization: Application Operating system Single operating system image per machine Software and hardware tightly coupled After Server Virtualization: App App App Operating system Virtualization layer Virtual Machines (VMs) break dependencies between operating system and hardware Running multiple applications on same machine often creates conflict Manage operating system and application as single unit by encapsulating them into VMs Underutilized resources Strong fault and security isolation Hardware-independent

The Virtual Server Concept • Virtual servers seek to encapsulate the server software away from the hardware • This includes the OS, the applications, and the storage for that server. • Servers end up as mere files stored on a physical box, or in enterprise storage. • One host typically house many virtual servers (virtual machines or VMs). • A virtual server can be serviced by one or more hosts e. g. storage, services, etc

The Virtual Server Concept Figure 1: Hypervisor layer between Guest OS and hardware

Hypervisors And Hosts • A hypervisor is a piece of computer software, firmware or hardware that creates and runs virtual machines. • A computer on which a hypervisor is running one or more virtual machines is defined as a host machine. • Each virtual machine has a guest operating systems, which is managed by the hypervisor. • Multiple instances of a variety of operating systems may share the virtualized hardware resources.

Hypervisors and Virtual Machines Server 1 Guest OS Server 2 Guest OS Hypervisor x 86 Architecture Intercepts hardware requests Clustering Service Console

Popular hypervisors • Xen • KVM • QEMU • virtual. Box • VMWare

Types of hypervisor Type 1 (bare-metal) Type 2 (hosted) VM 1 Guest Host VM 1 VM 2 Process VM 2 Guest Hypervisor OS Hardware VMware ESX, Microsoft Hyper-V, Xen VMware Workstation, Virtual. Box, QEMU, KVM Figure 2: Types of hypervisor Host

Virtualization techniques • How to virtualize unvirtualizable hardware : • Full Virtualization • Use emulation technique to make hardware virtualizable. • Skip the critical instructions by means of these translations. • OS Assisted Virtualization or Para-virtualization • Modify guest OS to skip the critical instructions. • Implement some hyper-calls to trap guest OS to VMM. • Hardware Assisted Virtualization • Modify or enhance ISA of hardware to provide virtualizable architecture. • Reduce the complexity of VMM implementation.

Hosted Architecture

Bare-Metal (Hypervisor) Architecture

h/w supported virtualization • Added new instructions which makes Virtualization considerably easier for x 86. • Intel – IVT(Intel Virtualization Technology) • AMD – introduced AMD-V • OS stays in its original privilege level 0. • Attempts to access the hardware directly are caught and passed to VMM. • In other words a new privilege ring is setup for the VMM.

Reflection Question What are the benefits of Hypervisors

Benefits and Features • Host system protected from VMs, VMs protected from each other • I. e. A virus less likely to spread • Sharing is provided though via shared file system volume, network communication • Freeze, suspend, running VM • Then can move or copy somewhere else and resume • Snapshot of a given state, able to restore back to that state • Some VMMs allow multiple snapshots per VM • Clone by creating copy and running both original and copy • Great for OS research, better system development efficiency • Run multiple, different OSes on a single machine • Consolidation, app dev, …

Benefits and Features (cont. ) • Templating – create an OS + application VM, provide it to customers, use it to create multiple instances of that combination • Live migration – move a running VM from one host to another. • No interruption of user access • All those features taken together -> cloud computing • Using APIs, programs tell cloud infrastructure (servers, networking, storage) to create new guests, VMs, virtual desktops

References • http: //www. vmware. com/pdf/virtualization. pdf • An Introduction to Virtualization and Cloud Technologies to Support Grid Computing. I. M. Lorente. EGEE 08.