3. Data Center Overview
3.7. Virtualization
Traditionally all applications are run separately on individual servers; servers are loaded differently and in most cases, for reasons of performance, more servers are in operation that are required. However, developments in operating systems allow more than one application to be provided per server. As a result, operating resources are better loaded to capacity through this “virtualization” of services, and the actual number of physical servers is drastically reduced.
A distinction is made between two different types of virtualization:
• Virtualization by means of virtualization software (e.g. VMware)
• Virtualization at the hardware level (e.g. AMD64 with Pacifica)
The virtualization of servers and storage systems continues to make great strides, as we already mentioned in sections 1.8 and 1.10. The advantages of this development are obvious.
• Less server hardware is required.
• Energy requirements can be reduced.
• Resource management is simplified.
• The patching between components is clearer.
• Security management can be improved.
• Recovery is simplified.
• Application flexibility is increased.
• Acquisition and operating costs can be reduced.
The advance of virtualization can include the following effects on data center cabling:
• Connections that are higher performance, so-called “fat pipes”, are required because of increased network traffic (data volumes).
• More connections are required for each server and between switches because of aggregation (trunking).
• An increased number of additional redundant connections are created as a result of increased demands on data center failure safety.
3.7.1. Implementing Server / Storage / Client Virtualization
The primary goal of virtualization is to provide the user a layer of abstraction that isolates him or her from the actual hardware – i.e. computing power and disk space. A logical layer is implemented between users and resources so as to hide the physical hardware environment. In the process, every user is led to believe (as best as possible) that he or she is the sole user of a resource. Multiple heterogeneous hardware resources are combined into one homogeneous environment. It is generally the operating system’s job in this process to manage in a way that is invisible and transparent to users.
The level of capacity utilization for all infrastructure components increases in data centers as a result of the increased use of virtual systems like blade servers and Enterprise Cloud Storage. For example, where servers were previously loaded to only 15 to 25 percent, this value increases to 70 or 80 percent in a virtualized environment. As a result, systems consume significantly more power and in turn generate many times more waste heat.
The adjacent graphic shows the development of server compaction.
Client Virtualization,or so-called desktopvirtualization,is a result of the ongoing development of Server and Storage Virtualization. In this process, a complete PC desktop is virtualized in the data center instead of just an individual component or application. This is a process that allows multiple users to execute application programs on a remote computer simultaneously and independent of one another.
The virtualization of workstations involves individually configured operating system instances that are provided for individual users through a host. Each user therefore works in his or her own virtual system environment that in principle behaves like one complete local computer. This is a different process from providing a terminal server in which multiple users share resources in a specially configured operating system.
The advantages of a virtual client lie in its individuality and its ability to run hosts at a central location. Resources are optimized through the common use of hardware.
Disadvantages arise as a result of operating systems which are provided redundantly (and the associated demand for resources), as well as the necessity of providing network communication to operate these systems.
Classic Structure
Theadjacent graphicshows anexam- ple of a classic server and storage structure in a data center with separate networks.
Each server is connected physically to two networks, the LAN for commu- nication and the SAN for storage media.
This leads to an inefficient use of all available storage capacities, since each storage of an application is handled separately and its reserved resources must be made available.
Servers are typically networked to- gether via copper cables in the LAN/access area in the data center. Glass fibers are the future-proof cable of choice in the area of aggregation and cores.
Fibre Channel is the typical appli- cation for data center storage.
SAN Structure
A network with SAN switches can greatly increase the efficiency of storage space in the network.
Data can be brought together into fewer systems, which perform better and are better utilized.
This behavior in the LAN, or more precisely SAN, is like that of the Internet, where storage space exists in a “cloud” whose actual locality is un- important.
Storage consolidation and storage virtualization are often terms that come up in this context.
The advantage of Fibre Channel is that it optimizes the transfer of mass data, i.e. a block-oriented data transfer. This advantage over the Ethernet has led to Fibre Channel being the most commonly used transmission protocol in SANs.
Server
LAN aggregation & core switch
LAN access switch Ethernet FC
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Storage…..
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FO Copper Server FC SAN switch LAN aggregation & core switchLAN access switch Ethernet FC
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Virtual Storage FO Copper3.7.2. Converged Networks, Effect on Cabling Classic LANs and SANs use different transmission pro- tocols, typically Ethernet for LAN and Fibre Channel for SAN.
However, LANs, as communication networks and SANs as storage networks are merging (converging) more and more.
Current transmission protocols under continuous deve- lopment support this standardization and are paving the way for a structure with FCoE, Fibre Channel over Ethernet.
The following 3-Stage Migration Path per the Fibre ChannelIndustryAssociation(FCIA:www.fibrechannel.org) is presented below. This process is based on hardware reusability and the life cycles of the individual components.
Stage 1
The introduction of a new switch, a so-called Converged Network Switch, allows existing hard- ware to be reused.
It is recommended in smaller data centers that storage systems be directly connected via this Converged Switch. A dedicated SAN switch would be required in larger structures so as to avoid bottlenecks. Converged Adapters are required for the server connection.
FCIA recommends SFP+ as its transceiver inter- face of choice (fiber optic & copper). Since a copper solution is possible only over 10 meters using Twinax cables, fiber optic cables must replace copper ones in these “converging” net- works.
Stage 2 Stage 3
The Converged Switch is upgraded with an FCoE uplink in a second migration stage and connected to FCoE in the backbone.
The final FCoE solution is connected directly to the core network. FC as an independent protocol has dis- appeared from the network.
Server LAN aggregation & core switch
FC SAN switch LAN access switch Ethernet Ethernet FC Storage FC FC FO Copper Server LAN aggregation & core switch
10G converged network switch FC SAN switch Ethernet FCoE FC Storage FC FC FC FO SFP+: Twinax or FO Server LAN aggregation & core switch
10G LAN access switch FCoE SAN switch FCoE FCoE FC Storage FC FO Copper FCoE Server LAN aggregation & core switch
10G LAN access switch FCoE FCoE FCoE Storage FO Copper FCoE
3.7.3. Trends
More than half (54 percent) of the IT infra- structure components in the SME segment in Germany have already been moved into the “cloud”. According to one study, this translates to somewhere in the middle range of this sector when compared with all of Europe. Number one is Russia with 79 per- cent, followed closely by Spain with 77 per- cent and France with 63 percent. The Dutch are currently still the most reluctant in this area, with 40 percent.
Over 1,600 decision makers throughout Europe from businesses with up to 250 em- ployees were asked about their use of vir- tualization and cloud computing for a study
by the market research institute Dynamic Markets, commissioned by VMware. In addition to 204 mid-sized com- panies from Germany, companies from France, Great Britain, Italy, the Netherlands, Poland, Russia and Spain also participated in the survey carried out from the end of January to the middle of February of 2011.
The cloud service used most often by mid- sized companies in Germany is memory outsourcing (68 percent). Applications used in the cloud include e-mail services (55 percent) and office applications for pro- cessing files, tables and spreadsheets (53 percent).
According to the study, the company management in over a third of the companies surveyed supports the cloud strategy. This is a sign that German mid- sized companies do not judge cloud computing to be a topic that is purely IT- related.
The management of those companies surveyed see cloud computing’s greatest advantages in not only lower costs for IT maintenance (42 percent), hardware equipment (38 percent), as well as in reduced power costs (31 percent), but also in improved productivity and cooperation from IT personnel themselves. All in all, 76 percent of German SMEs stated they achieved lasting benefits through cloud computing. Accordingly, about a third of the companies surveyed are also planning to extend their cloud activities in the next twelve months.
Virtualization as a Prerequisite for Cloud Computing
A key technical prerequisite for providing IT services quickly and flexibly is virtualization. This was the opinion of 82 percent of the SMEs in Germany. Already 75 percent of the German mid-sized companies that were surveyed have virtualized.This number is thus greater than the average for all of Europe (73 percent).Russia is again a step ahead in this area with 96 percent.
"The technological basis for setting up a cloud environment is a high level of virtualization, ideally 100 percent", according to Martin Drissner of the systems and consulting company Fritz & Macziol. “That’s the only way you can guarantee that resources can be distributed and used flexibly.” According to Drissner, the cloud is not a revolution, but the next logical step in IT development. Cloud Computing would simplify and speed up processes and also lower costs. It is recommended that a private cloud, i.e. a solution internal to the company, be set up as a first step to entering the world of Cloud Computing.
Reasons for Virtualization
Cost-related arguments for virtualization are moving into the background more and more. Where previously points like reduction in costs for hardware (35 percent), maintenance (36 percent) and power (28 percent) were often the main drivers for virtualization in the data center, criteria like higher application availability (31 percent), greater agility (30 percent) and better disaster recovery (28 percent) are becoming more and more important, according to the survey. In addition, the aspect of gaining more time and resources is becoming an increasingly higher priority for those surveyed (27 percent), showing a desire to devote more time to projects that are more innovative than just focusing attention on purely IT operations.