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Combine the information from the Excel spreadsheet named ServerVirtRecommendation that notes a recommended split of servers between the Hyper-V host systems being acquired, and you get a

3 Planning, Sizing, and Architecting a Hyper-V Environment

5 For the Model Host Network Adapter and Memory, enter the configuration of your

planned Hyper-V server network adapter configuration for speed of the adapters and

number of adapters Also enter the amount of RAM that will be in the server, such as

8GB or 16GB or 32GB Then click Next

6 If you leave Set Virtual Machines per Host unchecked, the Recommendation Wizard

tells you how many of the physical servers you assessed will fit on this model

config-uration you have created If you check the check box, you can note whether you

want two, three, four, or more virtual sessions on the system Typically, you’d just let

the wizard recommend how many sessions you want on the server, so you would

leave the check box blank Click Next to continue

7 Import the text file you used in step 4 in the section “Setting Up the Microsoft VSA

Tool to Capture Data for the First Time” that has the names of the servers you

assessed Then click Next

8 Review your settings, and then click Finish

9 The wizard will go through the worksheets that were created in the data gathering

process, as well as go through the data captured and stored in the SQL server for the

systems that were specified in the text file This takes a minute or two, and you will

then be prompted to click the Close button

From the Microsoft Assessment and Planning Solution Accelerator screen, choose the View

Saved Reports and Proposals option Doing so opens an Explorer window that shows the

Excel spreadsheets and Word documents generated by the assessment tool Open the

ServerVirtProposal Word document that summarizes the recommendation on how many

Hyper-V virtual servers would be needed, the expected CPU utilization of the servers, and

the disk and network throughput of the servers Combine the information from the Excel

spreadsheet named ServerVirtRecommendation that notes a recommended split of servers

between the Hyper-V host systems being acquired, and you get a good baseline

recom-mendation on how to split the virtual guest sessions and what the anticipated workload

will be on each of the host servers Figure 3.9 shows some of the information from the

reports

Analyzing the Workload Demands of Existing Servers

Another way to review the workload and configuration of the servers in your environment

other than using the Server Consolidation Recommendation Report is to open the Excel

spreadsheet that is generated from the collection process Excel spreadsheets are generated

and dropped into the folder Documents\MAP\{database name} Open the spreadsheet

generated, and note the statistics about the servers being monitored

For network utilization, the report, as shown in Figure 3.10, notes the hostname, make

and model of the network adapters in the system (if multiple network adapters are in the

server, each adapter is assessed separately), bytes sent and received, packets sent and

received, and packet errors

FIGURE 3.9 C Sample assessment metrics produced from the VSA tool

FIGURE 3.10 Sample network utilization report

3 Planning, Sizing, and Architecting a Hyper-V Environment

For physical disk utilization, the report notes the hostname, the type of disk configured,

total capacity of the disk, % disk read and write time, % idle time, average disk bytes/read

and bytes/write, average disks sec/read and sec/write, and average disk queue length

The logical disk utilization report notes the hostname, disk volume name, total capacity of

the drive, % disk read time, % disk write time, average disk sec/read and sec/write, and %

free space

The statistical information provided in the spreadsheet along with the Server

Consolidation recommendation report can provide valuable information about the server

demands of the systems being assessed for virtualization

Identify Servers That Are and Are Not Virtualization Candidates

With the recommendations from the Server Consolidation report and the data in the

Excel spreadsheet, you can validate certain servers as good candidates for virtualization

These servers are likely the utility servers (DHCP, DNS, domain controllers), an

assump-tion discussed earlier in the secassump-tion “Candidates for Immediate Virtualizaassump-tion to Guest

Sessions,” but are validated from the real-world statistical assessments

Other servers that might have been iffy as to whether they would be good candidates for

virtualization can be validated from the statistics You can confirm whether the workload,

disk I/O, network I/O, or other server performance metrics data indicate the server is or is

not a good candidate for virtualization

Combining Virtual Server Workloads to Create Optimized Host Servers

From the data generated, combining server workloads together to logical host server

configurations is the next step Balancing servers so that all the servers with high

proces-sor demands aren’t all put on the same host server but rather distributed across different

host servers is the goal

The Server Consolidation report generated from the VSA makes suggestions on appropriate

server balance By combining the required memory statistic with disk and network I/O,

the network administrator can now determine how many host servers are needed, how

much memory each server should have, how many processors are recommended, and

what type of disk and LAN configuration is recommended

Choosing the Hyper-V Host System Environment

With the statistical data acquired from the Microsoft VSA analyzed and grouped together

for optimum host configurations, the next task is choosing the host environment that

Hyper-V will be implemented on This is a decision whether the Hyper-V host will be

implemented on a physical server or whether the Hyper-V host will be implemented on a

blade server along with other physical servers or other Hyper-V host configurations

Hyper-V on a Dedicated Host Server

For organizations consolidating physical servers to virtual servers, usually an initial server

used for Hyper-V virtualization is an existing server in the environment (typically a four

or eight core system with a lot of memory, 16GB to 32GB) The system may have been

earmarked for a database server or messaging server, but instead has been allocated as the

host virtual server Or the organization might have purchased the server specifically with

host virtualization in mind

The dedicated physical server is like other servers on the network, with processors,

memory, internal disk, and a network adapter or two The system would be configured and

have Windows Server 2008 x64-bit installed on it and have the Hyper-V role installed via

the process covered in Chapter 4, “Installing Windows 2008 Server and the Hyper-V Role.”

Hyper-V on a Blade Among Other Physical Servers

Some organization may choose to purchase a blade server that is a physical server system

with several server processor boards in the system So instead of having a physical server

with three or four virtual guest sessions running on it, the blade server has four or eight

blades in the server, with one or more of the blades running as a Hyper-V host with three

or four virtual guests running on the blade Therefore, a blade server with 8 blades can run

8 different instances of Hyper-V host, and each Hyper-V host can be running 3 or 4 virtual

guest sessions, thus allowing a single chassis to run 32 simultaneous server sessions

Blade servers can definitely consolidate servers down to a small footprint, where 32

physi-cal servers can end up in a single-rack chassis just 6 to 10 inches high

Sizing a Hyper-V Host System Without Existing

Guest Data

Although the exercise to assess the current workload of existing physical servers using the

Microsoft VSA provides great metrics to size a Hyper-V host system for existing systems,

the process of sizing the Hyper-V host system is not as precise for many organizations

bringing up brand-new guest sessions without historical data

To take an educated guess at the sizing of the host system, since most servers in a data

center are running less than 10% server utilization, there is typically plenty of excess

server capacity available, and an administrator can take a pretty good guesstimates on

server load

Because each virtual guest session is a completely running operating system, the

installa-tion of as few as three or four high-performance guest sessions could quickly bring a server

to 50% or 60% of the server performance limits So, putting together a good educated

guess is important in the process

3 Planning, Sizing, and Architecting a Hyper-V Environment

Sizing Your Windows Server 2008 Server to Support Virtualization

The host Windows 2008 server needs to run Windows Server 2008 x64-bit edition

Although the minimum requirements for server compatibility for Windows 2008 applies,

because server virtualization is the focus of this server system, the minimum Windows

2008 server requirements will not suffice to run Windows 2008 virtualization

In addition, although Windows 2008 theoretically has maximum processor and memory

capabilities that reach into a dozen or more core processors and hundreds of gigabytes of

RAM, the reality on the scaling of Windows virtualization comes down to the raw

capabil-ities of network I/O that can be driven from a single host server In many environments

where a virtualized guest system has a relatively low system utilization and network traffic

demand, a single host system can easily support a dozen, two dozen, or more guest

sessions In other environments where a virtualized guest session has an extremely high

system utilization, lots of disk I/O, and significant server communications traffic I/O, the

organization might find a single host server maximizes its capacity with as few as seven or

eight guest sessions

RAM for the Host Server

With the lack of any other historical information, the rule of thumb for memory of a

Windows 2008 server running Hyper-V is to have 2GB of RAM for the host server plus

enough memory for each guest session Therefore, if a guest session needs to have 2GB of

RAM and there are three such guest sessions running on the host system, the host system

should be configured with at least 8GB of RAM If a guest session requires 8GB of memory

and three of those systems are running on the system, the server should be configured

with 24GB of memory to support the three guest sessions, plus at least 2GB of memory for

the host system itself

Processors for the Host Server

The host server itself in Windows 2008 virtualization has very little processor I/O

require-ments In the virtualized environment, the processor demands of each guest session

dictate how much processing capacity is needed for the server If a guest session requires 2

cores to support the processing requirements of the application, and 7 guest sessions are

running on the system, the server should have at least 15 cores available in the system

With quad-core processors, the system needs four processors With dual-core processors,

the system needs at least eight processors

With Windows 2008 virtualization, each guest session can have up to four cores dedicated

to the session, or processing capacity can be distributed, either equally or as necessary to

meet the performance demands of the organization By sharing cores among several

virtual machines that have low processing needs, an organization can more fully utilize

their investment in hardware systems

Disk Storage for the Host Server

A host server will typically have the base Windows 2008 operating system running on the

host system itself, with additional guest sessions either sharing the same disk as the host

session or the guest sessions being linked to a SAN or some form of external storage for

the virtualized guest session images

Each guest session takes up at least 4GB of disk space For guest sessions running databases

or other storage-intensive configurations, the guest image can exceed 10GB, 20GB, or

more When planning disk storage for the virtual server system, plan to have enough disk

space to support the host operating system files (typically about 2GB of actual files plus

space for the Pagefile) and then disk space available to support the guest sessions

Running Other Services on the Hyper-V System

On a system running Hyper-V, an organization would usually not run other services on

the host system, such as making the virtual server also a file and print server, or making

the host server a SharePoint server, or so on Typically, a server running virtualization is

already going to be a system that will maximize the memory, processor, and disk storage

capabilities of the system So, instead of impacting the performance of all the guest

sessions by having a system-intensive application such as SharePoint running on the host

system, organizations choose to make servers running virtualization dedicated solely to

the operation of virtualized guest sessions

Of course, exceptions apply to this general recommendation If a system will be used for

demonstration purposes, frequently the host system is set up to run Active Directory

Domain Services, DNS, DHCP, and other domain utility services So, effectively, the host

server is the Active Directory system Then, the guest sessions are created to run things

like Microsoft Exchange 2007, SharePoint 2007, or other applications in the guest sessions

that connect back to the host for directory services

Planning for the Use of Snapshots on the Hyper-V System

A technology built in to Hyper-V is the concept of a snapshot A snapshot uses the

Microsoft Volume Shadow Copy Service (VSS) to make a duplicate copy of a file; however,

in the case of virtualization, the file is the entire virtual server guest image The first time

a snapshot is taken, the snapshot contains a compressed copy of the contents of RAM on

the system along with a bitmap of the virtual disk image of the guest session If the

origi-nal guest image is 8GB in size, the snapshot will be significantly smaller in size; however,

the server storage system still needs to have additional disk space to support both the

orig-inal disk image plus the amount of disk space needed for the contents of the snapshot

image

Subsequent snapshots can be taken of the same guest session; however, the way VSS

works, each additional snapshot just identifies the bits that differ from the original

snap-shot, thus limiting the required disk space for those additional snapshots to be just the

same as needed for the incremental difference from the original snapshot to the current

snapshot This difference might be just megabytes in size

Taking into account whether snapshots will be used and how they will be used is

impor-tant in sizing the Hyper-V host server because this will require more disk storage for the

host system as more snapshots are taken and stored

3 Planning, Sizing, and Architecting a Hyper-V Environment

Summary

Microsoft Hyper-V is not necessarily difficult to install Neither is it difficult to load up

guest images to the system To properly balance applications across multiple Hyper-V host

systems, however, an administrator must do some simple performance assessment and

planning

Common server images can be virtualized, such as domain controller services, DNS

services, DHCP services, web services, and the like And then there are server applications

that aren’t as clear-cut as to whether they are good candidates for virtualization, such as

database servers and clustered application servers

This chapter provided guidance that identifies servers that are commonly virtualized, and

then provided information about the Microsoft VSA tool, which enables you to assess the

performance demands of existing servers to calculate key server statistics that can be used

to determine the workload of existing servers With statistical information in hand, an

administrator can analyze the information and determine how to best place virtual guest

sessions across Hyper-V host systems

Best Practices

The following are best practices from this chapter:

Distribute virtual guest sessions across host servers so that a host server isn’t

over-loaded with too many guest sessions demanding processing speed, disk I/O

demands, or network I/O demands, but instead is balanced in a logical manner

Make sure to keep cluster pairs and redundant system services on separate host systems

so that a host server failure doesn’t bring down both the primary and the backup

image of a system You should balance the services across separate host systems

Consider keeping links server services such as frontend and backend servers on the

same host system to improve the communication link speed between the two server

sessions within the same host server

Make sure to not centralize virtual guest sessions and cause remote users to have to

traverse slow or unreliable WAN links to access their information To maintain the

quality of the user experience in the process, user access to information should be

equal if not better than before servers were virtualized

Plan for the number of virtual guest sessions you expect to have on a server to

prop-erly size the host system with respect to memory, processor, and disk requirements

Virtualize utility servers like DHCP servers, DNS servers, policy servers, and such that

typically have low utilization and are redundant throughout an enterprise

Evaluate whether certain servers such as file servers, print servers, global catalog

servers, servers in a DMZ or edge, and media servers are good candidates for

virtual-ization based on the organvirtual-ization’s workload of the systems

Use the Microsoft VSA tool to gather server statistics on running servers during normal

production hours to determine the overall usage of systems in the environment

Assess the information that comes out of the Microsoft VSA to determine which

servers are good candidates for virtualization and which servers are not as good of

candidates for virtualization

Combine statistical information of servers to determine the amount of memory,

processor requirements, disk I/O, and network I/O of guest sessions to determine the

proper size for each host system that’ll be added to the network

Allocate enough disk space to perform snapshots of images so that the disk

subsys-tem can handle both the required guest image and the associated snapshots of the

guest session

Consider keeping primary servers on physical server systems, and having secondary

or redundant servers virtualized so that the organization can get the fastest

perfor-mance on day-to-day queries against a physical server However, the organization

can have secondary servers as virtual server systems to minimize costs and

consoli-date backup systems

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Windows 2008 Hyper-V

Host and Guest

Installation

IN THIS PART