Server Virtualization and Network Management


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Server Virtualization and Network Management

  1. 1. Server Virtualization and Network Management White Paper Author: Dirk Paessler Published: August 2008 the network monitoring company
  2. 2. CONTENTS EXECUTIVE SUMMARY 3 WHY SERVER VIRTUALIZATION 4 NETWORK MANAGEMENT IMPLICATIONS OF VIRTUALIZATION 6 HOW VIRTUALIZATION WORKS 6 VIRTUALIZATION AND PAESSLER 9 About Paessler AG Founded in 1997 and headquartered in Nuremberg, Germany, Paessler AG builds cost effective software that is both powerful and easy to use. The product range is specialized on Network Monitoring and Testing as well as Website Analysis. Its products are used by Network Administrators, Website Operators, Internet Service Providers and other IT-Professionals worldwide. Freeware and Free Trial versions of all products can be down- loaded from Server Virtualization and Network Management Page 2
  3. 3. EXECUTIVE SUMMARY Server virtualization is the latest server, but equally important, it al- major technology trend in the data lows one application to use resour- center. Gartner predicts that virtu- ces across the corporate network. alization will be the highest-impact One of the promises of virtualiza- trend in IT infrastructure and ope- tion is the ability to allow applica- rations through 2012. tions to dynamically move from one Despite its limits, where server physical server to another as the virtualization has been applied ri- demands and resource availabilities gorously, it has both enormous and change, without service interrupti- positive impacts on corporate power on. and cooling expenses as well as Virtualization also mandates the data center capacity. It can extend use of storage-area networks (SANs) the lives of aging data centers and and detached storage. This drives even allow some large organizations the network further into the center to shut down some of their data of the IT infrastructure and archi- centers. tecture. And, this is just the first generation From a security standpoint, cen- of virtualization‘s impact. A second tralizing multiple applications on a generation technology, which allows single box creates single points of multiple virtual servers to share a failure, both in the physical server Links single operating system license, itself, and in its network connec- Gartner predicts that virtualization promises to allow even further tion. will be the highest-impact trend: consolidation. This can get to the point where 50-100 virtual servers When a virtualized server crashes, jsp?id=638207 run on a single physical box which or its network connection slows or can manage high-compute load breaks, it impacts all the applica- applications that are considered tions on that box. poor candidates for first-generation The implication for network plan- virtualization. ning is that a great deal more traffic Virtualization works by freeing will be centralized on a few large applications from the constraints servers instead of spread out across of a single physical server. It allows a large number of smaller compu- multiple applications to run on one ters on the data center floor. Server Virtualization and Network Management Page 3
  4. 4. Also, virtualization works best with detached, rather than attached WHY SERVER storage. This requires very fast, dependable network connectivity VIRTUALIZATION between servers and the storage Server virtualization has come just devices on the storage area network in time for IT departments caught (SAN). Organizations moving from between the pressure to cut costs attached storage, as part of virtua- in the face of a developing world- lization, will create a large increase wide recession, steadily increasing in network traffic. energy costs and maxed-out data centers. All of this increases the need for strong network management. Virtualization attacks the problem of the low utilization of single-ap- A highly virtualized environment plication servers. These proliferate lives or dies on the efficiency and in data centers of medium to very dependability of its data network. large enterprises. Failure of a physical server, connec- tion, switch or router can be very The server populations of many costly when it disconnects know- non-virtualized environments ave- ledge workers, automated factory rage about 20% utilization. The re- floors or online retail operations sult is a huge waste of power, which from vital IT functionality. is doubled since every kilowatt used has to be balanced with an equal Network management can provide amount of cooling to maintain the vital information for planning and servers at optimal operating tempe- testing virtualized environments. rature. For instance, determining which applications are not good candi- This also has grave implications dates for virtualization is vital. The for the lifespan of data centers as amount and character of network increasing numbers of facilities traffic can provide important clues run short of power, cooling and, in towards identifying those applica- some cases, floor space despite the tions. move to blade servers over the last few years. Virtualization avoids this problem by automating the management issues of stacking multiple applica- Links tions on a single server and sharing Savings trhough virtulization at BT in the UK: resources among them. This allows IT shops to increase BT%E2%80%99s_award_winning_ shift_from_dark_to_light_green their server utilization up to 80%. The impact of this on a large organization is demonstrated by the experience of BT in the UK. It achieved a 15:1 consolidation of its 3,000 Wintel servers and saved ap- proximately 2 megawatts of power and $2.4 million in annual energy costs. This helped to reduce server Server Virtualization and Network Management Page 4
  5. 5. maintenance costs by 90%, and BT their servers. One large server is disposed 225 tons of equipment less expensive to buy, operate and (in an ecologically friendly manner) maintain than even a small popula- and closed several data centers tion of small servers. The applica- across the UK. tion management automation that virtualization provides can save a This saving is even more remarka- smaller organization one, or more ble because it involved only Wintel full time equivalent IT employees. servers – BT also has a large popu- lation of Unix servers that were not These savings are being achieved factored into the savings. mostly through hypervisor virtu- alization as supplied by EMC‘s Not only did BT achieve huge ope- VMWare and other vendors. rating savings, partly by avoiding the need to build a new data center This technology requires each virtu- at an estimated cost of $120 al server to run its own copy of the million, it also received three top operating system. This is the prefer- European ecology awards for the red solution when applications run- reductions of its carbon footprint ning different OSs – for instance a from the program. mixed population of Windows, Unix and Linux or several different Unix During this process, BT continued flavors – are being virtualized onto a to grow its business steadily, which single physical server. However, this puts the lie to the common argu- has efficiency implications when a ment that companies and nations large number of applications on the have the choice of only expanding same OS are virtualized. their economies or cutting their environmental impacts. An emerging new approach, “ap- plication virtualization,” offers a Far from hurting business, BT’s more efficient solution in these project added credibility to the cases, allowing multiple virtualized green business consulting practice applications to share a single copy it launched earlier this decade in of an OS. Not only can this allow both in the European Union and more applications to run on a given United States. physical server, its proponents This is not an extreme example of claim that it also will allow efficient what can be accomplished. operation of high compute-load applications which are not good Clearly BT is a very large enterpri- candidates for hypervisor virtuali- se. Smaller companies will achieve zation. proportionately smaller savings in absolute numbers, but the percen- tages will hold up for organizations with server populations of 50 or more. This will allow them to ex- tend the effective lives of their data centers as well as saving on energy costs. Even smaller organizations may find benefits to virtualization, particular- ly when facing the need to upgrade Server Virtualization and Network Management Page 5
  6. 6. NETWORK The failure of a network switch or router in a highly virtualized MANAGEMENT environment could have a similar impact by shutting off access to as IMPLICATIONS OF many as 50-100 vital applications. VIRTUALIZATION A network management tool such as Paessler‘s PRTG Network Moni- At first glance it might seem that tor can provide instant notification virtualization by itself would have of the failure of either a Windows little impact on network manage- server or its network connection, ment. The same applications are allowing IT to take immediate ac- running in the same data center, tion to minimize the impact of the just on a different piece of hard- crash. ware. Second, part of the promise of However, a closer look shows that server virtualization is the ability to it does have network management share and shift resources, including implications. The extent of those disk space, from one application to implications varies, depending on another dynamically. the pre-virtualization architecture. In a multi-server environment, Overall virtualization is one of this mandates the migration from several forces combining to drive direct, attached storage (in which the network into the center of the the disk drives are attached directly IT infrastructure and displacing the to the server much as they are on mainframe. desktop and laptop computers) to This increases the importance of separate storage systems running network operations and the poten- on a storage area network (SAN), tial impact of interruptions, making which becomes part of the overall strong network management vital to network infrastructure. today‘s business. This migration has been ongoing since the late 1990s and has seve- HOW ral advantages in terms of flexibility VIRTUALIZATION and data protection. It will accelerate as server virtuali- WORKS zation works its way into shops still running applications with direct First, virtualization centralizes attached storage. applications on one or compara- tively few physical servers, making The disadvantage is that all access those, and their “last mile” network between applications and data now connections, single-points-of-failure must run over the network, and that can have a major impact on even small delays can create issues business operations when they fail. with many applications. Thus virtu- alized environments cannot tolerate Those who remember the green- network overloads or switch failu- screen operations of the 1980s res. This requires strong network know that when the central compu- management. ter failed, all work stopped in the office. A strong network monitoring tool Server Virtualization and Network Management Page 6
  7. 7. such as Paessler‘s PRTG Network However, identifying which applica- Monitor can provide real-time tions should remain on dedicated graphic monitoring of traffic at servers, is not always easy. critical points in the network and The volume and character of trans- can provide long-term usage projec- missions to and from these appli- tions. This helps network managers cations provides major clues toward anticipate traffic increases before identifying the applications, and a they impact service levels. strong network management tool, Third, applications with heavy com- such as PRTG Network Monitor, is pute or data read/write loads have the best source for that vital infor- not proven to be good candidates mation. for hypervisor virtualization. As a Fourth, server virtualization pro- result, wholesale virtualization can mises dynamic reassignment of create serious service level issues. underlying compute and storage Distributed environment PRTG PRTG Each application resides on a seperate physical server with attached storage. Consolidated through virtualization PRTG PRTG Three applications run in a virtual environments sharing the ressources of the virtualization server. Server Virtualization and Network Management Page 7
  8. 8. resources to meet spikes in demand large monthly and quarterly use on individual applications. cycles, but many others exist. This is the real key to increasing Again, in the un-virtualized envi- efficiency in resource allocation. ronment, each application has to have enough computing resources One major reason that the un-virtu- to deliver promised service levels alized environment is characterized under the maximum annual load. by such low utilization is that each For some applications, this means application needs sufficient com- a heavy investment in computing puter power, memory and storage resources that will remain idle to meet its maximum load plus an much of the time. overhead to accommodate future growth. Virtualization removes this problem by providing dynamic reallocation It is often difficult to predict the of computer resources. speed of growth, which tends to follow a “hockey stick” graph rather Demand on the separate applica- than a smooth curve – usage is low tions running in a data center can while users learn a new application operate on different cycles. An and then may jump quickly as they application experiencing a surge in become comfortable with it and demand at a given time can “bor- realize its potential for improving row” resources from another that is their work. in a low period of its demand cycle. Often many applications experience In the extreme case, virtualization major cyclical variations in demand vendors are promising the capabi- that may be weekly, monthly or lity to dynamically move an entire annual. Financials are the obvious application across the network from example of applications with very one server to another in order to Load Balancing load tx 80% A t load 80% B t With increasing user acceptance a new application (red) may require more ressources. This can easily be achieved at tx by moving one application (blue) to another virtual machine. Server Virtualization and Network Management Page 8
  9. 9. respond to such variations. detection of network and website problems easy and affordable. It Ultimately, this implies that all the helps organizations monitor criti- servers and storage devices running cal network resources and detect virtualized environments can, for systems failures or performance planning purposes, be treated as problems immediately, minimi- one large machine. Their resour- zing downtime and its economic ces be lumped together to meet impact. SNMP Helper enables the total demand of all virtualized PRTG Network Monitor to collect software running on them. detailed performance information As a practical matter, this may on Windows servers and work- only work inside a single data stations. Up to several thousand PRTG Network Monitor center since transmission delays parameters and performance Network availability and usage between centers could introduce counters on a PC can be monito- monitoring: red with just a few mouse clicks. performance issues. And, it will not work at all unless the network ■■ Webserver Stress Tool is a po- SNMP Helper connecting these physical servers werful HTTP-client/server test Windows performance monitoring: is fast and highly fault tolerant. application designed to pinpoint This requires high levels of network critical performance issues on management to guarantee perfor- a Web site or Web server that Webstress Server Tool mance. may obstruct delivery of an Load and Stress testing of websites: optimal user experience. By simulating simultaneous access VIRTUALIZATION by hundreds or thousands of simultaneous users, it tests Web AND PAESSLER server performance under normal and extreme loads to ensure that Paessler offers three applications critical information and service that form a complete network mo- are available at response times nitoring suite for small-to-medium that users expect. businesses and is used by large and All of these tools come in various very large enterprises to provide editions, and include a free edi- more detailed visibility into critical tion to allow users to try out their parts of their networks. main features before making the Paessler has re-architected all its purchase decision. tools recently, putting them on the optimal technological base and improving their overall functionality, efficiency and usability. Its tool suite consists of: ■■ PRTG Network Monitor is an easy-to-use Windows application for monitoring and classifying bandwidth usage and for moni- toring network uptime/downtime. the network monitoring company It provides live readings and Paessler AG • Burgschmietstrasse 10 long-term usage trends for net- 90419 Nuremberg • Germany work devices. PRTG makes early • Server Virtualization and Network Management Page 9