An Introduction to Server Virtualisation

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A loose definition

Virtualisation is a framework or methodology of dividing the resources of a computer into multiple execution environments, by applying one or more concepts or technologies such as hardware and software partitioning, time-sharing, partial or complete machine simulation, emulation, quality of service, and many others.

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Some history

− An old concept – first virtual machines created on IBM mainframes in early ’60s

− Typically, IBM's virtual machines were identical "copies" of the underlying hardware. Each instance could run its own operating system.

− Virtualisation formed the basis of “time sharing”

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Some virtual machines you may know…

− NT had Virtual DOS Machine (NTVDM) and Windows on Win32 (WOW)

− Windows 95 used virtual machines to run older (Windows 3.x and DOS) applications

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The old model

− A server for every application

− Software and hardware are tightly coupled

− Underutilised resources introduce real cost into the infrastructure

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The new model

− Physical hardware is abstracted by a virtualisation layer, or hypervisor

− Manage OS and application as a single unit by encapsulating them into virtual machines

− Separate OS and hardware and break hardware dependancies

− Optimise utilisation levels

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Increased Hardware Utilisation

• Before Virtualisation • After Virtualisation

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Underutilisation of Resources

• Most organisations over-provision− Multiple processors in

each server− Memory requirements

over-estimated

• Aim to drive up CPU utilisation

Actual DSS customer data – 120 servers monitored

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Virtual Infrastructure

• Virtual infrastructure brings uniformity to the data centre

• Dynamically map computing resources to the business

• Lower IT costs through increased efficiency, flexibility and responsiveness

• Provision new services and change the amount of resources dedicated to a software service

• Treat your data centre as a single pool of processing, storage and networking power

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How is it implemented?

− Typically, in order to virtualize, you would use a layer of software that provides the illusion of a "real" machine to multiple instances of "virtual machines". This layer is traditionally called the Virtual Machine Monitor (VMM) or “hypervisor”.

− The hypervisor could run directly on the real hardware or it could run as an application on top of a host operating system.

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Type 1 VMM

Hardware

VMM

GuestVM

GuestVM

GuestVM

IBM CP/CMSVMware ESX

Windows Virtualisation (2008)Xen

Virtual Iron

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Type 2 VMM

Hardware

VMM

GuestVM

GuestVM

GuestVM

Host OS

VMware Server

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Hybrid VMM

MS Virtual ServerMS Virtual PC

Hardware

VMM

HostVM

GuestVM

GuestVM

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Paravirtualisation

Paravirtualization is a virtualization technique that presents a software interface to virtual machines that is similar but not identical to that of the underlying hardware. This requires operating systems to be explicitly ported to run on top of the virtual machine monitor (VMM)

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Full Virtualisation

• Provides a complete simulation of the underlying hardware

• With binary translation, rewrites some x86 instructions at run time that cannot be trapped and converts them into a series of instructions that can be trapped and virtualised

• Capable of running existing legacy operating systems without modification

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Native Virtualisation

− Leverages hardware-assisted capabilities available in the latest processors from Intel (Intel VT – “Vanderpool”) and Advanced Micro Devices (AMD-V – “Pacifica”) to provide near-native performance.

− Virtual Iron is one of the first companies to offer virtualization software to fully support Intel-VT and AMD-V hardware assisted virtualization.

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Native Virtualisation

− Dell• Precision 380 Intel Pentium D• PowerEdge 430 Intel Pentium D• PowerEdge 440 Intel Xeon 3xxx• PowerEdge 1435 AMD Opteron 22x• PowerEdge 1950 Intel Xeon 5xxx• PowerEdge 1955 Intel Xeon 5xxx• PowerEdge 2950 Intel Xeon 5xxx

− HP• ProLiant DL140 G3 Intel Xeon 5xxx •  ProLiant DL320 G4 Intel Xeon 5xxx •  ProLiant DL360 G5 Intel Xeon 5xxx •  ProLiant DL365 AMD Opteron 22xx •  ProLiant DL380 G5 Intel Xeon 5xxx •  ProLiant DL385 G2 AMD Opteron 22xx •  ProLiant DL580 G4 Intel Xeon 7xxx •  ProLiant DL585 G2 AMD Opteron 82xx

− IBM• xSeries 100 Intel Pentium-D •  System x3455 AMD Opteron 22xx•  System x3550 Intel Xeon 5xxx •  System x3850 Intel Xeon 7xxx  HS21 Intel Xeon 5xxx •  LS21 AMD Opteron 22xx

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What’s in a Virtual Machine?

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What’s in a Virtual Machine - BIOS

• VM has its own BIOS• Has everything you

would expect to see in a real BIOS

• Boot options may include floppy, CD-ROM, disk drive and PXE.

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What’s in a Virtual Machine - Networking

• Each VM has a virtual NIC• Virtual NICs are connected

to virtual switches implemented in the virtualisation layer− VMware – vSwitches− Microsoft - .vnc-files

• Virtual switches have uplink connections to physical NICs on the host

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Combining internal and external virtual switches

• Virtual switch with one outbound adapter acts as a DMZ

• Backend applications are secured behind the firewall using internal-only switches

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What’s in a Virtual Machine - Storage

• To the applications and guest operating systems inside each virtual machine, the storage subsystem is a simple virtual SCSI host bus adapter connected to one or more virtual SCSI disks

• Virtual disks are files kept on physical storage.− VMware – VMDK files− Microsoft – VDF files

• Virtual disk represents a local drive on a virtual server, such as a C or D drive in Windows

• Physical storage could be− Direct attached SCSI− SAN attached− iSCSI− NAS

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Licensing Considerations

• On host− Host OS?− Virtualisation technology?

• On Guest− Guest OS?− Guest Applications

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Support Considerations

• Two meanings− Is it technically possible?− Will the vendor support a virtual environment?

• The Microsoft position− “For Microsoft customers who do not have a Premier-level support

agreement, Microsoft will require the issue to be reproduced independently from the non-Microsoft hardware virtualization software.”

− “Microsoft supports Windows Server System software running within a Microsoft Virtual Server environment subject to the Microsoft Support Lifecycle policy ... “ “

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Usage Scenarios for Virtualization

Consolidation

Workload Mobility

Business Continuity Management

Development and Test

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1. Logical

2. Physical

3. Rational

Gartner definition

Usage ScenarioProduction server consolidation

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Usage ScenarioProduction server consolidation

• Consolidate workloads− Infrastructure applications− Low-utilization workloads− Branch office and datacenter workloads− Efficient use of available hardware resources

• Re-host legacy OS and applications− NT4 guest applications on virtual platform

• Run on current hardware and current OS• No application updates required

• Partition resources− Limit CPU resource per VM

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Usage ScenarioBusiness continuity management

• Disaster Recovery− Maintain DR systems as virtual

machines− Eliminate traditional problems

associated with bare metal restores• OS and application patching

− Deploy and test patches off-production, and swap

− Eliminate scheduled downtime• Isolation / sandboxing

− Isolate OS environments for untrusted applications

− Prevent malicious code from affecting others

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Usage ScenarioDynamic datacenter

• Workload mobility− Package up entire OS environment and move to

other location− Flexible deployment of workloads

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Usage ScenarioDevelopment and test

• Rapid provisioning of virtual machines• Create arbitrary test scenarios• Wider test range for niche scenarios

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Application + OS: Now A Data File

• Server provisioning is similar to copying a file

• Server migration is now similar to data migration

• Data management techniques can be used for server management

• Server cloning/copying• Versioning• Server archival• Remote mirroring

Entire server – OS, apps, data, devices, and state – is now simply a file.

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The Role of Shared Storage

• Virtual Machine files are centrally located.

• Multiple access.• Virtual Machines can be

moved for DR purposes, system repair/upgrade, etc.

• Can take advantage of advanced SAN features such as snapshots, clones and replication.

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Live Migration

• Move running virtual machines from one physical system to another with no downtime

• Zero downtime maintenance• Balance resource utilisation across infrastructure

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Hardware Infrastructure – Scale Up or Scale Out?

• Scaling up means fewer, larger systems− Advantages

• Fewer ESX Server images to manage

• Lower infrastructure costs (Ethernet/SAN switches)

− Disadvantages• Higher hardware costs (servers)• Big H.A. impact in case of failure

of a node• Fewer CPUs supported "per rack“• Headroom required for HA is

expensive• Servers may go obsolete• Locked into server architecture

• Scaling out means more, smaller systems− Advantages

• Lower hardware costs (servers)

• Low H.A. impact in case of failure of a node

• More CPUs supported "per rack“

• Headroom required for HA is less expensive

• Not locked into obsolete hardware

• More flexible

− Disadvantages• Many hypervisor (ESX) images

to maintain• Higher infrastructure costs

(Ethernet/SAN switches)

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What should an enterprise ready virtualisation platform offer?

• Efficient server partitioning• SMP support in guest VMs• Scalable memory in guest VMs• Fault isolation – a crash in one virtual machine should

not impact other virtual machines• Security isolation – a virtual machine should never

access the memory or I/O operations of another virtual machine

• Resource isolation – runaway applications in one virtual machine should not “starve” others virtual machines.

• Non-disruptive addition of capacity• Scalable management tools

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VMware Workstation

• Desktop Virtualisation• Run multiple operating

systems simultaneously on a single PC

• Supports Windows, Linux, NetWare, Solaris

• Software development/test• Training

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VMware Server

• Free virtualisation platform• Type 2 “hosted” VMM• Runs on any standard x86 hardware • Runs on a wide variety of Linux and

Windows host and guest operating systems

• Intended as a “step up” to Type 1 hypervisor products.

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VMware Infrastructure 3

• VMware ESX Server 3.0 - Type 1 VMM

• VMware VirtualCenter 2.0• 4-way vSMP / 16GB Virtual RAM

support• VMware VMotion• VMware HA• VMware Distributed Resource

Scheduling• VMware Consolidated Backup

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Non-disruptive capacity on demand

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Automate resource assurance for critical applications

DRS Dynamic BalancingContinuous Optimization

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Automatic availability for all applications

VMWARE HA

X

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Backup anytime

VMWARECONSOLIDATEDBACKUP

Decouple backup from production VMs20-40% better resource utilizationPre-integrated with 3rd party backup products

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Microsoft Virtualisation Products

• Virtual PC• Microsoft Virtual Server 2005 R2 • Virtual Machine Manager (in Beta but available

for download)• Windows Virtualisation (to be released after

Longhorn)

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Virtual PC

• Suited to use in testing on a desktop environment

• Not recommended for production servers− Single CPU support only− No remote management possible− No SCSI support− Starts as an application not as a service

• Shares disk format with Virtual Server

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Virtual Server 2005 R2 SP1

• Microsoft’s current offering for virtualisation in production environments

• Shares underlying technology with Microsoft Virtual PC

• Web based management portal

• Guests supported include:− Windows (up to Vista with

SP1)− Linux

Virtual Server 2005 R2: Administration Website

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Clustering in Virtual Server 2005 R2 SP1

Host to Host

Cluster storage

SAN or iSCSI connection

Guest to Guest

Cluster storage

iSCSI connection

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Virtual Server 2005 R2 SP1

• VM Additions− VM additions provide enhanced performance and

additional functionality to the guest OS− Additions available for XP, Windows 2003, Vista and

Linux− Windows additions provide:

• Allow for direct mode kernel execution (faster processing of some commands)

− Linux additions provide:• Time sync• Shutdown support• SCSI disk• Does not allow for direct mode kernel execution

− Important to update for each new release to maximise performance benefits

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Windows Virtualisation

• To be released within 180 days after the Longhorn release (no Beta available as yet)

• Requires Intel VT or AMD Virtualisation hardware• Uses Hypervisor (a thin layer of software under

the “Host OS”)

Hardware

VMM (Hypervisor)

Guest 1(“Host OS”)

Guest 2

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Virtual Machine Manager

Virtual Machine Manager: Centralized management view

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Centralized Management: Reports

Full set of Full set of reports, reports,

integration with integration with MOM databaseMOM database

Actions one click Actions one click away in context away in context

sensitive Actions sensitive Actions PanePane

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Self Service Portal

Ability to control Ability to control owned virtual owned virtual

machinesmachines

Thumbnails of Thumbnails of all owned virtual all owned virtual

machinesmachines

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Self-Service PortalProvisioning

User selects from list User selects from list of templates of templates

Administrator has Administrator has associated with that associated with that

useruser

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Self-Service PortalProvisioning

New virtual machine New virtual machine ready for use, Terminal ready for use, Terminal

Services connection Services connection information information

automatically emailed to automatically emailed to user.user.

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Virtual Server 2005 vsWindows Server Virtualization

  Virtual Server 2005 R2 Windows Server Virtualization

32-bit VMs? Yes Yes

64-bit VMs? No Yes

Multi-processor VMs? No Yes, up to 8 processor VMs

VM memory support? 3.6 GB per VM More than 32 GB per VM

Hot add memory/processors? No Yes

Hot add storage/networking? No Yes

Can be managed by System Center Virtual Machine Manager?

Yes Yes

Microsoft Cluster support? Yes Yes

Scriptable / Extensible? Yes, COM Yes, WMI

Number of running VMs? 64 More than 64.As many as hardware will allow.

User interface Web Interface MMC 3.0 Interface

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Xen

• Open source hypervisor solution

• Installs on bare-metal• Linux VMs fully supported

− Red Hat− Debian− Suse

• Windows VMs require Intel VT or AMD-V processor− Microsoft Windows Server

2000− Microsoft Windows Server

2003 − Microsoft Windows XP SP2

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XenSource

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XenSource Products

User Profile Enterprise IT, system integrators

Windows IT professionals

Developers, testers, support, IT enthusiasts

Windows guest support

Windows Server 2003; Windows XP; Windows 2000 Server

Windows Server 2003; Windows XP; Windows 2000 Server

Windows Server 2003; Windows XP; Windows 2000 Server

Linux guest support Red Hat EL 3.6, 3.7, 3.8, 4.1, 4.2, 4.3, 4.4, 5.0; SUSE SLES 9.2, 9.3, 10.1; Debian Sarge

N/A (Windows guests support only)

Red Hat EL 3.6, 3.7, 3.8, 4.1, 4.2, 4.3, 4.4, 5.0; SUSE SLES 9.2, 9.3, 10.1; Debian Sarge

Live Migration Mid-2007 N/A N/A

Shared storage Mid-2007 N/A N/A

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Virtual Iron

• An enterprise ready native virtualisation platform

• Uses hardware-assisted virtualisation technologies of Intel VT and AMD-V processors

• Based on an open source hypervisor derived from the Xen open source project

• No software need be installed on physical hardware

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Virtual Iron Components

Component License Function

Hypervisor GPL First software loaded when physical server boots. Manages all hardware resources

Service Partition

GPL Second software loaded when physical server boots. Manages virtual server creation and configuration and all I/O.

Virtualisation Manager

Commercial Controls virtual servers through an agent in the service partition

Guest operating systems

Varies Operating systems that are fully virtualised on a physical server

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Virtualization Manager

• Java-based application

• Allows for central management of virtualized servers

• A physical server can have many virtualized servers, which are run as unmodified guest operating systems.

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Virtual Manager Policy-based Automation

• LiveMigration – moves a running virtual server from one physical server without pausing or impacting running applications

• LiveCapacity – monitors virtual server CPU utilisation or other application needs to determine when a workload needs additional capacity. When a user-defined threshold is met, the virtual server is LiveMigrated to a physical server that has the necessary resources

• LiveRecovery – monitors the status of physical resources and moves virtual servers to maintain uptime in the event of a hardware failure

• LiveMaintenance – moves virtual servers to alternative locations without downtime when a physical server is taken offline for maintenance

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Virtual Iron Architecture

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Supported Configurations

Feature Support

Operating systems 32 and 64-bit Red Hat Enterprise Linux 432 and 64-bit SUSE Linux Enterprise Server 932-bit Windows XP32-bit Windows 2003

Processors Intel Xeon with Intel VTAMD Opteron with AMD-V

Virtualised Nodes 100s per virtual data centre

Processors per virtual Server Up to 8

RAM per Physical Server Up to 96GB

Virtual servers per physical server CPU Up to 5

Virtual NIC adapters per virtual server Up to 5

Virtual disks per virtual server Up to 16

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Virtuozzo

− Operating System–Level Virtualisation

− Creates multiple, isolated virtual environments (VEs)

− Whereas VMs attempt to virtualize "a complete set of hardware," VEs represent a "lighter" abstraction, virtualizing instead "an operating system instance"

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Parallels Workstation

• Test/Development solution aimed at desktop market

• Uses hypervisor technology

• Wide guest OS support− Entire Windows family - 3.1,

3.11, 95, 98, Me, 2000, XP and 2003

− Linux distributions Red Hat, SuSE, Mandriva, Debian and Fedora Core

− FreeBSD − “Legacy” operating systems

e.g. OS/2, eComStation and MS-DOS.

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HP Virtual Server Environment

• Implemented on HP Integrity and HP 9000 systems

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Physical to Virtual (P2V)

• P2V is the term used to describe the process of converting physical servers into virtual machines

• Can be performed while server is live• Some operating systems require cold migration• Process:

− Analyse source− Create a target VM− Transfer data from physical source to virtual target− Transform VM

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VMware Converter

• Replaces P2V Assistant• Wizard based conversion

process• Can convert physical

machines, virtual machines or third party system images (e.g. Symantec Ghost, Backup Exec LiveState Recovery)

• Source physical machines:− 64-bit Windows XP/2003− WinNT SP4+− Windows 2000− Windows XP− Windows 2003

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Platespin PowerConvert

• “Anywhere to anywhere” conversion− Peer-to-Peer

• Physical to Virtual (P2V)• Virtual to Virtual (V2V)• Virtual to Physical (V2P)• Physical to Physical (P2P)

− Image Capture• Physical to Image (P2I)• Virtual to Image (V2I)

− Image Deployment• Image to Virtual (I2V)• Image to Physical (I2P)

− Disaster Recovery• Physical to Virtual (P2V)• Virtual to Virtual (V2V)

• Windows and Linux sources can be converted

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Platespin PowerConvert

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Portlock Storage Manager

• Third-party NetWare data management product

• Can be used for P2V conversions of NetWare servers

• Requires some manual reconfiguration of VM

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Capacity Planning

• Important first step in any server consolidation project

• Aims:− Understand server performance and utilization rates

of a group of servers− Identifying servers that are good candidates to be

migrated into virtual machines − Size virtual environment accurately

• Statistics are gathered and processed• What-if scenarios can be run to examine

different possible approaches

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VMware Capacity Planner

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Inventory AnalyseWorkload Data

Collection

Recommend

Platespin PowerRecon

• Onsite data collection and analysis• Scenario modelling (what-if)• Agentless operation

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Some additional products…

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VMware Lab Manager

• Create centralised pools of VMs, storage and network components

• Rapid setup and tear down of test/dev environments

• Maintain library of customer and production system environments

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VMware ACE

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VMware Virtual Desktop Infrastructure

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Dunes VS-0

http://www.dunes.ch/content/view/82/157/

Dunes VS-O

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− esxRanger Professional• LAN/WAN backups• Backup active servers• Database of backup activity

− esxReplicator• Replicate changes to remote

location – “chunked” by time or data change volumes

• Effective business continuity

Virtual Machine Backup and Replication

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Virtual Machine Backup and Replication

• esXpress− Virtual Backup Appliance

runs backup jobs within a VM

− Offloads CPU and memory utilisation from VMware ESX console

• Virtual Solution Box− Also implemented as a

virtual machine appliance

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esxCharter

A Windows based esxtop and more…

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esxMigrator

• Assists customers upgrading from VMware ESX 2.X to VMware ESX 3.0

• Uses data manipulation strategies that can copy virtual disks much faster than allowed by the VMware console

• Enables failback contingency

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Best Practice Recommendations

• Explore your options. • Evaluate your applications for potential

consolidation. • Understand the differences between various

virtualization solutions. • Look closely at the licensing and support

policies of your software vendors. • Start small.

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Best Practice Recommendations

• Manage expectations. • Beware of “virtual sprawl.” • Consider blades as a complementary

consolidation strategy. • Integrate server consolidation with a broader

consolidation strategy. • Develop a framework for continuous

consolidation.