Server Virtualization with VMware Information Technology Server Virtualization with VMWare A look at server virtualization, what it is and why it should be considered. By Alex Dewar, Head of IT & IM Solutions, Excitech Ltd. Whether it is in the server room enabling servers to be deployed more efficiently and managed more flexibly, or on the desktop enabling Apple Mac computers to run both MacOS and Windows at the same time, Virtualization is clearly a technology whose time has come and it is rapidly moving out of the Enterprise market and into the SME (Small to Medium Sized Enterprise) mainstream by offering compelling benefits to all but the smallest of companies. Virtualization is a tried and tested technology which is transforming the way that organisations deploy and manage their IT. Although today s common x86 computer architecture was originally designed to run just one operating system and one application at a time, Virtualization breaks those limitations, making it possible to run multiple and potentially different operating systems concurrently on the same system, each with their own settings and installed programs. This can improve the utilisation of expensive hardware resources; allowing them to be deployed and managed much more flexibly. Figure 2: Virtualized Server Architecture This article focuses primarily on server Virtualization using VMware Virtual Infrastructure, but will also serve to explain Virtualization concepts in general. How It Works In the field of computing the word virtual is synonymous with quasi, pseudo or seems to be. So Virtual Memory seems to be and behaves like real RAM (Random Access Memory). A virtual machine therefore seems to be and behaves like a real computer. Virtualization allows a physical computer to emulate multiple computers (virtual machines) concurrently. Then, so far as the virtual machines operating systems are concerned, they are completely unaware that they are running on a virtual rather than a physical computer. Figure 1: Traditional Server Architecture www.excitech.co.uk/dpj Excitech Ltd 2008 Design Productivity Journal Volume 4, Issue 5 51
Information Technology Server Virtualization with VMware Different Approaches to Virtualization Virtualization is delivered by a computer program whose task it is to create, run and monitor virtual machines. This program is often named a Hypervisor and there are fundamentally two types, Bare Metal and Hosted Hypervisors. The term Bare Metal Hypervisor refers to a Virtualization Hypervisor that exists as a thin layer of software running directly on the computer hardware. Whereas a Hosted Hypervisor runs as a program on top of a host operating system such as Windows or Linux. 80s and 90s Hiatus With the rise to ascendancy of personal computing and PC based client-server computing based on servers running first Novell Netware and later Windows NT Server and Linux, there was a hiatus for Virtualization during the 1980s and 1990s. This is because rather than sharing a central expensive mainframe computer resource, computing power and storage capacity was distributed among relatively inexpensive server and desktop islands which could each be upgraded or replaced individually, so more performance could be plugged in where it was needed. x86 Virtualization But during the 1990s desktop PCs became ubiquitous and the number of servers performing individual business functions exploded. This created the need for a new wave of Virtualization, this time in the x86 environment. The main drivers were: Figure 3: Bare Metal Hypervisor Low server utilisation with many servers only using 10% to 15% of their performance or capacity. Increasing operating costs for space to store servers, power and cooling. Need to enhance disaster recovery and high availability capabilities. Need to provision new servers quickly and easily. Demand to dynamically allocate server performance according to peaks and troughs in server workloads. These demands led to VMware creating their first x86 server Virtualization solutions in the late 1990s. Since then they have continued to grow, develop and innovate, and remain the clear market leaders in this field. Figure 4: Hosted Hypervisor Whilst the Hosted Hypervisor model of Virtualization is fine for testing, software development, technical support and experimentation; for serious Virtualization projects a Bare Metal Hypervisor will provide greater scalability and reliability and is therefore recommended. In the table below I have listed some mainstream Virtualization products and indicated which category they fall into. Server Bare Metal Hypervisor VMware ESX and ESXi Microsoft Windows 2008 Server Hyper-V Hosted Hypervisor VMware Server MS Virtual Server The Benefits of Virtualization There are many significant business benefits offered by Virtualization and whilst they may not all apply to every organisation, most, apart from the very smallest, will find the arguments for Virtualization compelling. Better Server Utilisation In all but the smallest of organisations, servers tend to perform single roles such as domain controller, file server, print server, SQL server, email server, etc. This segregation keeps individual server configurations simple and ensures that a problem on one server or in one application does not impact on other network services. But often, according to market research firm IDC, servers tick over at 10% to 15% memory and processor utilisation. So a company with a number of servers is paying Desktop VMware Workstation MS Virtual PC Parallels Desktop Some History Mainframe origins Virtualization is not a new technology. It was first developed by IBM in late 1960s as a means of enabling their mainframe computers to run multiple applications at the same time and to flexibly manage these expensive resources. Figure 5: Server Consolidation 52 Excitech Ltd 2008 Design Productivity Journal Volume 4, Issue 5 www.excitech.co.uk/dpj
Server Virtualization with VMware Information Technology for a lot of unused performance. Virtualization offers a means to consolidate servers, to run multiple servers in virtual machines on a single physical system, thus improving utilisation while still retaining the reliability benefits of segregating roles across multiple servers. Less Space, Power and Cooling Even when a server is ticking over at 10% utilisation it is still taking up space, consuming electricity, and creating heat which in turn creates a cooling demand. In larger organisations the space, power and cooling of servers is a significant cost. Virtualization helps by reducing the number of physical servers which are needed, which can result in significant savings. Precautionary Management Well managed IT departments take very seriously the need to provide high levels of up-time for critical network services. Hence they must minimise the risk that installing new software, or applying a patch update, will inadvertently lead to downtime, performance degradation or unreliability. With Virtualization it is possible to clone a virtual machine in order to test updates prior to installing them on live systems, and to create snapshots prior to updates so that if anything goes wrong the system can be quickly rolled back to its previous state. Disaster Recovery and High Availability Because IT is now business critical, organisations are taking Disaster Recovery and High Availability much more seriously. High Availability is about ensuring that if a server fails then the business service (such as file or email) that it is providing can be brought back online with minimal data loss in the shortest possible time. Disaster Recovery is about ensuring that in the case of a site-wide disaster such as a fire, that the business can be brought back online in a new location, again with minimal data loss in the shortest possible time. Cloning and snapshot capabilities, alongside tight integration with industry standard backup and replication applications ensure that Virtualization can support an organisation s DR and HA targets. Simplicity of Provisioning New Servers Because a virtual machine is stored as a group of files, Virtualization creates myriad opportunities for simplifying the provisioning and management of servers. I have already mentioned cloning and snapshots. With Virtualization we can also create Server Templates from which a new Windows Server or Linux virtual machine can be created in minutes. A dramatic improvement over the time it takes to procure, and build, and install a traditional server. In fact Virtualization is transforming the way some software vendors are making their products available to trial or purchase. Many software products are now available as ready-made virtual machines called Virtual Appliances which you can download, install and run on your virtual server. Ease of Tuning Server Performance and Storage Once an organisation has more than one virtual server a whole new set of opportunities for more flexibly managing server performance and capacity arise. Tools are available to adjust the share of the virtual server s processor and RAM resources available to each virtual machine, and even to dynamically load balance so that virtual machines are moved seamlessly between servers with no downtime. This last capability might sound alarming but is completely safe and after thorough testing has been adopted by significant numbers organisations who have adopted Virtualization. It is even possible with a pool of virtual servers to migrate all the virtual machines off one server so that it can be shut down for a repair or hardware upgrade, with no loss of network services. Then once the virtual server is back up and running, the load can be balanced across all virtual servers again. Extending the Life of Legacy Applications Some organisations continue to run discontinued or bespoke legacy applications on old servers and old server operating systems such as NT 4 Server because these applications are essential to the operation of the organisation. Often these servers are out of warranty so the organisation is left running a critical application on old and unsupported hardware. Then because the application may have been written for an old operating system it may not be possible to purchase new, compatible server hardware. Virtualization can offer these legacy applications a new lease of life because the physical server environment can be converted (migrated) into a virtual machine and therefore run on new supported hardware, potentially with more performance and more storage space. VMware or Microsoft Excitech s philosophy when it comes to recommending IT Solutions to customers is to select products which combine the attributes of being market leaders, well established, having an excellent support infrastructure, being competitively priced, and being a good fit for the size and requirements of our customers. When it comes to server Virtualization the products which fulfil all of these criteria are VMware s ESX, ESXi and Virtual Infrastructure. VMware are the clear market leaders with a sophisticated, comprehensive, and tried and tested product range. In the server market nobody else comes close. Many of you will be aware of Microsoft s product announcements about Windows 2008 server with their Hyper-V Bare Metal Hypervisor (previously codenamed Viridian). Clearly Microsoft is taking the Virtualization market very seriously and is gearing up to win significant market share, but at the moment its solution is still a Release 1 product. In terms of track record, completeness and availability, VMware are the clear choice and are likely to remain so for the next couple of years at least. VMware Infrastructure and VMware ESXi VMware s Bare Metal Server Virtualization products are available in a number of flavours which I will outline here. VMware s flagship server Virtualization product is VMware Infrastructure which includes the VMware ESX Server platform plus a suite of complementary utilities. VMware also offer a free Virtualization platform called VMware ESXi which is available as a free download and also a purchase-time option on servers from certain manufacturers such as HP. www.excitech.co.uk/dpj Excitech Ltd 2008 Design Productivity Journal Volume 4, Issue 5 53
Information Technology Server Virtualization with VMware VMFS VMFS is VMware s file system which is used to format the disk area where the virtual machines are stored, whether they are stored on the virtual server in very small installations, or more usually on a Fibre Channel or iscsi SAN shared storage. VMFS has been specifically designed by VMware to allow multiple VMware servers to access the same logical disk on a SAN. Virtual SMP Virtual Symmetric Multi-Processing enables a single virtual machine to use up to four physical processors. Figure 6: VMware Infrastructure Consolidated Backup VMware Consolidated backup is an underlying technology framework which allows backup software from market leading vendors such as Symantec to back up the logical disks where virtual machines are The following table outlines the key differences between these products, the next section details what the additional products in the suite do. Elements of the VMware Virtual Infrastructure Suite VMware ESX VMware ESX is the core component of VMware Infrastructure. It includes the Bare Metal Hypervisor allowing the creation, running and monitoring of multiple virtual machines. VMware ESX is a 64-bit operating system which can support multiple processors or processor cores, up to 256GB of physical RAM and up to 32 logical CPUs making it scalable up to very large servers. Figure 7: VMware Consolidated Backup Product VMware ESXi VMware Infrastructure Foundation VMware Infrastructure Standard VMware Infrastructure Enterprise Single Server Partitioning (previously Starter) Virtualization for Small Businesses or Branch Office High Availability Infrastructure Virtualization Suite for Any Workload Enterprise-class Infrastructure Virtualization Sute for the SDynamic Data Centre VMware ESX or ESXi VMFS Virtual SMP VirtualCentre Agent Consolidated Backup Update Manager VMware HA VMotion Storage VMotion Virtual DRS VirtualCentre Server Available as a separately licensed product. Licensed on a per-server basis separate from VMware Infrastructure 3 editions. 54 Excitech Ltd 2008 Design Productivity Journal Volume 4, Issue 5 www.excitech.co.uk/dpj
Server Virtualization with VMware Information Technology stored instead of backing up the virtual machines themselves. This reduces LAN traffic, reduces backup times, and reduces the performance load on virtual machines while they are being backed up. on, this is a tried and tested technology, and allows larger VMware installations to maximise server performance continuously without manual intervention. Update Manager VMware Update Manager is a patch management solution from VMware which can patch both ESX Server and the operating systems and applications running on the individual virtual machines. VMware HA VMware HA protects against the failure of a physical server by automatically restarting its virtual machines on another VMware ESX server. Figure 10: VMware DRS VirtualCentre Management Server VMware VirtualCentre provides centralised management for multiple VMware virtual servers and is strongly recommended in all but the smallest of installations. It brings the management of multiple servers together in one interface. Figure 8: VMware HA VMotion VMotion is a utility to migrate a live virtual machine from one ESX Server to another, securely and with no downtime or client disruption. Storage VMotion Storage VMotion is a utility to migrate the files which comprise a virtual machine from one SAN to another, or from one logical disk in a SAN to another with no downtime or disruption. Figure11: Virtual Centre VMware Converter VMware Converter migrates from various source servers to create a new virtual machine. Apart from physical source servers, other sources can include: Figure 9: VMotion VMware DRS VMware Distributed Resource Scheduler (DRS) allows virtual machines to be grouped together and managed as a load balancing cluster. Once this is done, virtual machines are moved around automatically and seamlessly using VMotion according to user defined criteria to ensure that the business s performance and redundancy criteria are met. Whilst it might seem alarming to think that you do not know without checking what virtual server your virtual machine is running Other VMware virtual machines. Microsoft Virtual PC Virtual Machines. Microsoft Virtual Server Virtual Machines. VMware Converter is available as a free Starter version, or a more advanced Enterprise version which integrates with VirtualCentre Management Server. Who Should Consider Server Virtualization? The majority of medium to large organisations and many smaller www.excitech.co.uk/dpj Excitech Ltd 2008 Design Productivity Journal Volume 4, Issue 5 55
Information Technology Server Virtualization with VMware organisations should seriously consider Virtualization. Consider Virtualization if you: Have multiple servers; the more servers you run the more compelling the arguments for Virtualization. Wish to enhance your Disaster Recovery or High Availability readiness. Wish to minimise the risk of downtime. Wish to provision new servers quickly or frequently. Wish to flexibly balance the load so that your servers make the cost effective use of your hardware investment. For further information about Virtualization, please visit www.excitech.co.uk/dpj4506 Glossary General Terms: Virtualization Hypervisor Virtual server Virtual machine Trade Names: Microsoft Virtual Server Microsoft Virtual PC VMware Server VMware Workstation VMware Infrastructure VMware ESX VMware ESXi Product A generic term for running multiple simulated computers (including their operating systems and programs) concurrently on a single physical computer. The central software component of Virtualization which runs the virtual machines. There are two forms of hypervisor, a Bare Metal Hypervisor which is installed directly on the server with no underlying operating system, and a Hosted Hypervisor which runs on top of Windows, Linux or some other operating system. A physical server running a Virtualization Hypervisor in order to host virtual machines. A computer system emulated in software. Microsoft s Hosted Hypervisor Virtualization software for servers. Microsoft s Hosted Hypervisor Virtualization software for desktops. VMware s Hosted Hypervisor Virtualization software for servers. VMware s Hosted Hypervisor Virtualization software for desktops. VMware s Bare Metal Hypervisor Virtualization suite comprising VMware ESX and various utilities. VMware s commercial Bare Metal Hypervisor. VMware s free Bare Metal Hypervisor. Is Your IT Infrastructure in Good Health? Businesses are often affected by the reliability and suitability of their IT infrastructure. At worst, this can be disastrous. At best, this can lead to system inefficiency, frustration and increased costs. If IT systems are to support business process rather than restrict them they require ongoing maintenance and periodic review. Excitech can provide a comprehensive review of your company s IT systems and deliver qualified advice on effectiveness, ongoing suitability and vulnerabilities. The IT Health Check Fully qualified consultants review five key areas of your company s IT infrastructure and provide a professional report that offers a strategic review of the suitability, scalability, security of the system and its ongoing management requirements. Network Topology & Structure Network Devices Network Performance Network Security Systems Management For further information on Excitech s IT Healthcheck service visit www.excitech.co.uk/aps29 or call 0845 370 1500. For more information, see inside back cover 4514 or to ask a question, email: alex.dewar@excitech.co.uk 56 Excitech Ltd 2008 Design Productivity Journal Volume 4, Issue 5 www.excitech.co.uk/dpj