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Handbook
1DESIGNING A MISSION-CRITICAL INFRASTRUCTURE
2VIRTUAL APPLICATION PERFORMANCE TESTING: AN ART FORM
3THE PROS AND CONS OF VIRTUALIZING SQL SERVER ENVIRONMENTS
4EXCHANGE 2013 STORAGE CONSIDERATIONS WHEN VIRTUALIZING ON HYPER-V
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Virtualizing Mission- Critical ApplicationsMission-critical applications no longer have to be confined to physical hardware. But before you virtualize the applications that keep your business running, learn how to avoid performance and availability issues.
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
2 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
EDITOR’S NOTE
Getting to Know Your Enterprise Apps
Many companies have moved past the question of “Why should we virtualize
our enterprise applications?” to “How should we virtualize them?” Yes, security,
performance and availability are still major concerns for these important applica-
tions, but the advantages of virtualization often outweigh those issues—which
can generally be addressed with good testing, migration and management policies.
In this handbook, Mark Vaughn offers an overview of issues concerning virtu-
alizing enterprise applications, including tier-one and mission-critical applica-
tions. By detailing the various types of applications that can be safely virtualized,
he outlines how to design a virtual architecture that will sustain even perfor-
mance-intensive apps. The trick, he says, is understanding and preparing for the
particularities of each application before migrating.
Supporting that idea of getting better acquainted with your applications, Mike
Nelson’s article discusses the important of testing virtual apps. Nelson outlines
steps for evaluating how your application will perform in a virtual environment,
but his most important point is that there’s no one approach that will work every
time in the dynamic world of virtualizing a company’s critical resources—hence
why he defines testing as more of an art form than an exact science.
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
3 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
The final articles in this handbook provide guidance for virtualizing two of the
most critical and commonly used applications. Basit Farooq takes you through the
pros and cons of virtualizing SQL Server and Serdar Yegulalp gives valuable tips
concerning storage for IT pros looking to virtualize Exchange 2013 with Hyper-V.
With their advice, you’ll find out if your organization is ready to virtualize its
applications. n
Laura Aberle
Associate Features Editor
EDITOR’S NOTE
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
4 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
1MISSION- CRITICAL
INFRASTRUCTURE
Designing a Mission-Critical Infrastructure
In IT, many users have abandoned physical servers and traveled far down the
virtualization road. As virtualization has moved from the trendy minority to the
trusted majority, those who have resisted it are considered dinosaurs clinging to
yesterday’s practices. But one has to ask, “Are they resisting the inevitable or are
they simply protecting their business?”
When the ability to conduct business is on the line, IT departments exercise an
abundance of caution. For some, the prospect of virtualizing mission-critical appli-
cations has been considered off-limits because, frankly, why fix what isn’t broken?
But over the past few years, this “Why fix what isn’t broken?” mentality has shifted
concerning virtualizing critical applications.
WHAT IS A MISSION-CRITICAL APPLICATION?A mission-critical application is an essential component of core business func-
tions. A failure or interruption in a mission-critical application can have a severe
impact on an organization’s ability to conduct business. The term tier-one appli-
cation is often used synonymously, though it refers to the performance needs of
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
5 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
1MISSION- CRITICAL
INFRASTRUCTURE
an application. A tier-one application requires finely tuned resources and reliable
hardware to provide the desired performance metrics. While it cannot be said that
all mission-critical applications are also tier-one applications, it is highly likely
that any tier-one applications will be mission-critical.
So, first, it may be time to revisit the “Why fix
what isn’t broken?” philosophy of deploying mission-
critical applications. Five years ago, if a physical server
used only a third of the available processing power, or
just a fraction of the available memory resources, it
would be labeled as broken. That is exactly where we
find ourselves in today’s data center. A physical server
now holds more compute resources than the average
operating system or software platform can use. In a
physical server environment, efforts are being need-
lessly replicated, valuable resources are left untapped, and power consumption is
increasing. At the same time, the value of these mission-critical applications is
constant. What was once conservative and safe is now beginning to look broken.
With the power of modern server hardware and hypervisors, you no longer
sacrifice high-end performance to gain the high-availability and resource con-
sumption benefits of virtualization. Given their ability to fully exploit the vast
amount of resources available in modern x86 servers, virtual platforms can often
A physical server now holds more compute resources than the average operating system or software plat-form can use.
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
6 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
1MISSION- CRITICAL
INFRASTRUCTURE
yield the same performance as physical servers, if not better.
A virtual server is also portable, no longer tied to a specific piece of hardware. In
terms of availability and disaster recovery, this is a significant advantage. Whereas
recovering a physical system often requires a second set of identical hardware, al-
most any x86 hardware can now be enlisted to recover a virtual server. And what
application could be more in need of a solid and efficient disaster recovery or
high-availability solution than a mission-critical application? In fact, even if an
application’s virtual performance may not match the performance in a physical
environment, availability gains could outweigh small dips in performance.
CONSIDERATIONS FOR VIRTUALIZING MISSION-CRITICAL APPSOnce the decision has been made to virtualize, you need to build appropriate
strategies for virtualizing mission-critical applications. You may need to develop
unique strategies for each. If one application has multiple components, evaluate
the benefits of affinity and anti-affinity rules, which control where virtual ma-
chines (VMs) can be located, to either keep components on the same physical host
or to force them to run from separate hosts. In some cases, you may want to run
from the same host to improve performance. Other applications may require the
resilience of spreading infrastructure components out on different hosts. You may
also need to organize hypervisor clusters or use affinity rules to adhere to licensing
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
7 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
1MISSION- CRITICAL
INFRASTRUCTURE
requirements. Though it is rare, you may also want to consider dedicating an entire
virtualization host to one VM. This is usually done for licensing or performance
reasons. Even though it does not aid in consolidation and reducing footprint, it
provides advantages in the areas of availability and recoverability.
Another critical decision is how to move the workload from a physical
server to a virtual one. While physical-to-virtual (P2V) conversion tools may be
adequate for other applications, be careful about using them with mission-critical
applications. The settings of the OS and subsequent applications were originally
customized for a physical server, and though conversion tools are designed to find
and adjust these settings during migration to a VM, a setting can be overlooked.
When every millisecond counts in the performance and availability of an applica-
tion, you don’t want to bring over artifacts from an install that was not intended
for the virtual server.
Treat this migration like a hardware refresh. The operating system and appli-
cations should be installed fresh. Where feasible, even configuration files should
be created anew. Recognizing that manually recreating configurations may also
introduce risk, use your knowledge of the application or contact the application
vendor for advice in deciding which configurations can be safely migrated without
carrying over legacy attributes.
Since each application may require a unique approach, below are some ex-
amples of the thought process behind a few popular mission-critical workloads.
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
8 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
n Web servers. Web servers are often inexpensive resources, almost a commodity
in many organizations. They have low resource demands and are often deployed
in groups. Few organizations would consider a Web server a mission-critical
application. But an Internet presence is essential to conducting business in today’s
environment. Targeting Web servers are a win-win for virtualization. They have
a small footprint that is easy to virtualize, and they benefit greatly from the high
availability and agility offered by virtualization. Demand for Web servers can also
be closely linked to seasonal trends and business cycles, allowing them to benefit
from virtualization’s ability to rapidly deploy and decommission VMs.
The best method is to first create a virtual Web server and migrate a website to
it, as that will result in a cleaner VM. However, Web servers are generally highly
tolerant of minor imperfections in OS configurations. Though not always rec-
ommended, Web servers can also be virtualized using physical-to-virtual (P2V)
migration tools.
n Application servers. Application servers cover a range of performance profiles.
Depending on the application they host, they can be anything from a small server
hosting a simple JSP or .NET application to a large server hosting a complex
Java application. Size and complexity of application servers often have a direct
correlation to the role an application plays within a business. With a complex
Java application, the application server is both mission-critical and a tier-one
1MISSION- CRITICAL
INFRASTRUCTURE
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
9 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
1MISSION- CRITICAL
INFRASTRUCTURE
resource—and the size and complexity of the application also make it difficult to
deploy. Regardless of whether it is physical or virtual, deploying an application
server requires precision tuning of the OS and the application.
Virtualization provides several advantages here. In many cases, the underlying
infrastructure is more easily tuned in a virtual environment: This includes net-
work devices, CPU resources, memory and other key resources. After the tedious
task of tuning infrastructure, the OS and the application to achieve the desired
performance, virtualization allows you to quickly
and easily create a clone of that VM. This makes
future deployments more efficient and accurate. By
decoupling the VM from the physical hardware, it
also insulates the application server administrators
from having to reproduce this effort every time a
new hardware platform is adopted.
As application performance can be closely linked
to underlying infrastructure, do not take the task of
virtualizing an application server lightly. Though
not difficult, it can be a time-consuming task of tuning resources, measuring
performance and then adjusting resources again. Under no circumstances should
you use a P2V migration tool to virtualize a mission-critical, tier-one application
server. This brings over too many legacy settings from one hardware platform to
Never use a phys-ical-to-virtual migration tool to virtualize a mis-sion-critical app-lication server.
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
1 0 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
1MISSION- CRITICAL
INFRASTRUCTURE
another, and overcomplicates the configuration tasks required to create a stable
environment.
n Database servers. Unlike Web servers and application servers, database servers
are rarely configured to spread production workloads across multiple resources.
More often, databases are deployed in an active/passive cluster as a single stand-
alone resource. Database servers can be even more complex and sensitive to OS
configurations than application servers, and significantly more resource-intensive.
All these attributes should indicate a flashing caution sign for any virtualiza-
tion administrator who wants to virtualize a database server workload. But even
the biggest and most complicated database servers
can benefit from virtualization. Granted, some da-
tabases may require 100% of a virtualization host’s
resources, but the high-availability and portability
features provided may justify the effort.
Many databases can exploit software cluster-
ing features to provide a rapid recovery of database
services in the event of a hardware failure. Unfor-
tunately, these features can also require expensive
licensing and result in a very complex configuration. The more complex a con-
figuration, the more likely it is to experience issues from human error. In contrast,
The more complex a con figuration, the more likely it is to experience issues from human error.
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
1 1 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
1MISSION- CRITICAL
INFRASTRUCTURE
most hypervisors provide high-availability features that can move a failed database
server to new hardware and reboot it almost as quickly as software clustering can
restore the same database services. High availability within the hypervisor does
not require additional database software licensing and will not require any com-
plicated configurations in the database environment. What may add only one to
two minutes to automated recovery tasks can save hours in maintenance tasks.
Like an application server, a database server must be tuned to the specific hard-
ware resources and operating system that make up the underlying infrastructure.
While this makes the use of P2V tools difficult, it also complicates the task of
restoring a reliable database service on disaster recovery hardware. However, when
the database server is built and tuned for virtual hardware, almost any x86 server
platform will make a suitable recovery host.
n Microsoft Exchange. Microsoft Exchange is an excellent example of a high-
performance environment that thrives on virtual hardware. At the same time,
Exchange 2010 introduces new features that illustrate why it is important to know
your application before you virtualize it.
Microsoft Exchange 2010 introduced Database Availability Groups (DAGs).
A DAG synchronizes data from multiple servers, allowing for almost immediate
failover of a workload with a purely software solution. A DAG will work between
any combination of virtual and physical hardware platforms. With this feature and
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
1 2 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
1MISSION- CRITICAL
INFRASTRUCTURE
the relative ease of deploying and maintaining it, why virtualize Exchange? Vir-
tualization still provides several advantages in an Exchange environment. While
software features may offer a rapid failover of services, a down server will still lead
to diminished capacity. While the environment runs on diminished resources, the
remaining servers are carrying additional workload, increasing the risk of a second
and more costly failure. This is where a hypervisor platform can quickly detect a
failure and reboot a VM on another server, thus restoring redundancy within the
environment.
Since Microsoft Exchange supports the live migration of mailboxes, using P2V
tools to move a physical Exchange deployment to a virtual environment is not
necessary.
MEASURE TWICE, MIGRATE ONCENever forget that you are dealing with critical infrastructure. These environments
should already have monitoring tools in place to measure response times, perfor-
mance metrics and availability. Before making changes, have solid data to provide
a baseline of how the environment behaved prior to those changes.
Also ensure that you have at least 45 days of data, to include any weekly and/
or monthly business cycles that may generate fluctuations in usage and perfor-
mance. If an application slows down the week after it is virtualized, no one will
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
1 3 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
acknowledge that the performance is normal during month-end processing. All
that users will know is that you virtualized the application and now it is slow. Have
before-and-after snapshots to defend against these attacks or to troubleshoot the
valid issues that may emerge. The more granular the reporting, the better. Some
issues will be real, most will be imagined, but all must be given the attention that
mission-critical applications deserve.
There is a difference between what can be virtualized and what should be vir-
tualized. However, in the end, the arguments against virtualizing mission-critical
applications are simply losing their validity. The advantages to virtualizing these
applications are too great to overlook. With a well-designed virtual solution, it
is very difficult for an organization to argue against virtualizing. —Mark Vaughn
1MISSION- CRITICAL
INFRASTRUCTURE
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
14 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
2PERFORMANCE TESTING
Virtual Application Performance Testing: An Art Form
Once you prioritize which applications to virtualize, it’s important to test their
performance. Application performance testing is the best way to learn how virtual
applications will fare in a virtual infrastructure and what the end-user experience
will be like.
Virtual application performance testing is exactly that—testing. Some people
consider it a science, but I think of it as an art form. You can get creative with
testing to generate the best performance, but it won’t replicate how your virtual
applications will perform in production.
PRE-TESTING FACTORS: SOFTWARE AND THE USERSApplication performance testing is an essential part of any solid virtual application
plan—particularly for tier-one and mission-critical applications. By performing
some quick load tests—with some willing users enlisted as guinea pigs—you can
experiment with the hypervisor and the apps themselves to achieve the desired
performance results.
But as you tinker with virtual applications, don’t neglect user experience. If a
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
1 5 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
2PERFORMANCE TESTING
virtualized application runs as well as it did on physical hardware (or better), you
shouldn’t worry too much about users’ expectations.
In some cases, though, you might think twice about virtualizing an applica-
tion if, as a result, it would no longer look the same
on the user’s end. For example, if an application is
visually intensive and is not a true client/server
app, but rather a simple Remote Desktop Protocol
(RDP) session-accessed application, a user’s daily
interactions with the application are most impor-
tant. Virtualizing applications saves resources and
space—which is great for admins—but it won’t
always benefit the user.
Finally, remember that not everyone has the
luxury of a full-blown testing lab or the available users for application perfor-
mance testing. Thankfully, some software manufacturers produce load-testing
software from application vendors themselves to third-party providers.
VIRTUAL APPLICATION PERFORMANCE TESTING CONSIDERATIONSThe following are some important factors to consider before you begin virtual
application performance testing.
Virtualizing applica-tions saves resources and space—which is great for admins— but it won’t always benefit the user.
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
1 6 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
2PERFORMANCE TESTING
n Host affinity. What are the application vendor requirements, if any? Can you
run one application on the same host—or even in the same Distributed Resource
Scheduler (DRS) or high-availability cluster—as another application? Host affinity
is a requirement in some infrastructures, and in others it just makes good sense.
n Resource affinity. Again, is this a vendor requirement? It may be necessary
to dedicate quantities of the core five resources—CPU, RAM, disk, network in-
terface cards and USB—to ensure the best performance and support for virtual
applications.
n Shares and resource pools. In my experience, these resources don’t enter into the
equation until the end of the process, but you should consider resource quantities
up front. Determine the amount of resources your guest machine and its virtual
applications will use. Don’t leave the hypervisor’s resource allocation at the de-
fault amount. You can fine-tune shares throughout the application performance
testing process to see what’s best for each virtualized application.
n Dedicated clusters. To improve performance and management, create a cluster
with an isolated set of servers that host common or interacting applications.
n Application stacking. With the ultrafast and capacity-heavy hosts that exist
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
1 7 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
2PERFORMANCE TESTING
today, it’s possible to stack two or three applications on one virtual server. But
it’s not advisable with bigger applications. Stacking can be a great thing, but it
can also be problematic if virtual applications don’t cooperate with one another.
n Inter-application cooperation. From the physical server world, we know all too
well that some applications just don’t play well with others in the sandbox. Some
virtualized applications won’t interact well with others on the same guest, host
or cluster. And some just cannot be virtualized at all.
As you begin virtual application performance testing, create a baseline of serv-
ers and a load that’s as similar as possible to what’s on the physical server. It’s not
always possible to test virtual applications with 100% accuracy, but you should be
able to get close. Also, keep in mind that some problems might emerge only after
testing is done and you compare the data. If you think of application performance
testing as an art, you’ll find some creative ways to boost performance.
—Mike Nelson
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
1 8 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
3SQL SERVER
The Pros and Cons of Virtualizing SQL Server Environments
Virtualization is a hot trend in the computing world, offering businesses
substantial cost and performance benefits that include server consolidation, re-
duced power consumption and the effortless creation of virtual development and
test environments. As a result of this trend, many organizations are interested in
virtualizing SQL Server, and for a good reason. The benefits of virtualized environ-
ments increase business continuity and allow database administrators (DBAs) and
IT professionals to build an agile IT infrastructure. But many DBAs are unsure if
the benefits of virtualizing SQL Server are worth the risks.
ADVANTAGES OF VIRTUALIZING SQL SERVERn Reduced data center footprint with database server consolidation. Production
SQL Server environments can benefit from server consolidation with virtualiza-
tion because it can drastically reduce the number of physical servers and minimize
the administrative workloads through centralized management. With Hyper-V
technology, we can host multiple virtual database servers on the same physical
machine while maintaining complete isolation at the operating system level. This
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
19 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
3SQL SERVER
allows us to manage performance, security, manageability and business continuity
for each virtual application server independently. It also gives us the flexibility
to run multiple operating systems on the same hardware, as required by specific
applications.
This means we can virtualize multiple underutilized physical SQL servers on a
single powerful physical server. As a result of this approach, we end up managing
a small number of physical servers, which simplifies the administration, reduces
operational, maintenance and hardware costs, and saves data center space.
n Reduced licensing and operational costs. As mentioned, reducing the number
of physical database servers also reduces data center operational costs because of
reduced power and cooling requirements.
Furthermore, by virtualizing SQL Server environments, we can make signifi-
cant license cost savings, because the number of licenses required is reduced. For
example, each physical server requires licenses for the operating system and utility
software. By reducing the number of physical servers, we ensure we do not need
these additional licenses.
License costs are also dependent on the software and technology used for vir-
tualization. For example, with Windows Server 2008 R2 Hyper-V, we can eliminate
the need to purchase separate virtualization software. We can reduce the license
cost even further by taking advantage of premium edition licensing. For instance,
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
2 0 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
3SQL SERVER
we can purchase licenses for our physical servers, and then use those physical
servers to run as many instances of SQL Server within virtual machines (VMs).
Remember, though, we can host only three VMs on a Windows Server 2008
Standard Edition licensed physical server and an unlimited number of VMs with
a Windows Server 2008 Enterprise Edition licensed physical server.
n Better manageability through centralized administration. The virtualization
of SQL Server environments simplifies administration because we can manage
these VMs from a single location using such tools as Remote Desktop Services
(RDS) or System Center Virtual Machine Manager, which help DBAs and IT
professionals manage their physical and virtual infrastructure from a central
location.
n Improved high-availability and disaster recovery solutions. A virtualized SQL
Server environment provides improved high-availability and disaster recovery
features. For example, we can cluster our physical hosts running Hyper-V, back
up our Virtual Hard Disk (VHD) or implement guest OS clustering using the SQL
Server AlwaysOn feature. This will ensure that our environment is protected
against virtualized infrastructure failures such as SQL Server instance failure. We
may also use database mirroring to protect our critical SQL Server environment
from a shared-drive failure.
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
2 1 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
3SQL SERVER
DISADVANTAGES OF VIRTUALIZING SQL SERVERn Scalability and performance. Although virtualization is suitable for most situ-
ations, it is not always the right solution. For example, it is not ideal to virtualize
CPU- or memory-intensive SQL Servers. Also, virtualization requires additional
hardware resources, but the problem is that it’s almost impossible to estimate in
advance how many additional resources will be needed. In addition, some SQL
servers can experience performance degradation after they are virtualized. Prop-
erly benchmark the performance of SQL Server in the virtual environment and
test the solution carefully before implementing it in the production environment.
n Single-point failure. Fault tolerance is another issue with virtualizing SQL
Server environments, since hardware failure on the host will also bring down all
guests running on that host. This problem can be eliminated by clustering hosts.
n Security. Security is also a concern in virtualized SQL Server environments. If
the security of your host is compromised, the security of all guests running on
that host will also be compromised.
n Software support. Many software vendors still do not support their applications
if you are hosting their application databases in a virtualized environment. When
you consider going virtual, keep all these concerns in mind. —Basit Farooq
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
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Exchange 2013 Storage Considerations When Virtualizing on Hyper-V
The Exchange Server virtualization scenarios available today are much
broader than those of a few years ago. Restrictions remain, but they are far less
obtrusive. This year, many companies will examine virtualizing Exchange 2013 on
Microsoft Hyper-V. The most glaring restrictions here are the storage require-
ments, which are critical to Exchange virtual machine (VM) mailbox databases
and transport queues.
If you’re migrating to the newest version of Exchange and preparing for a virtual
setup, you should know exactly how virtualized Exchange 2013 storage will work.
Here are the five most important aspects to keep in mind:
1.Virtual disk size for all Exchange instances must be fixed. Like many hyper-
visor and VM products, Microsoft Hyper-V lets you create virtual disks that
will dynamically expand up to a predetermined size. For example, if you desig-
nate a virtual disk with a 250 GB maximum size, but you’re only using 100 GB,
the corresponding dynamically expanding virtual disk file will be only 100 GB.
Fixed-size virtual disks, however, use a virtual disk file. Virtual disk files
pre-allocate all the space required for the virtual disk. In other words, a 250
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
2 3 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
4EXCHANGE SERVER
GB virtual disk will use a 250 GB file. Fixed disks will help eliminate the per-
formance issues you may see with dynamically expanding disks.
2.Block-level storage is required for all direct-attached devices. Hyper-V al-
lows for direct-attached storage (DAS), which in turn lets a VM directly write
to a storage device instead of to a virtual-disk file on said device. This increases
performance. However, any such direct-attached devices must use block-level
storage; they can’t be network-attached storage (NAS) devices. However, they
can be iSCSI, Fibre Channel over Ethernet or another storage area network
(SAN)-type device.
The reason for this is simple. For Exchange 2013 storage to function properly,
Exchange needs low-level access to the device because of how it works with its
databases; NAS doesn’t expose enough low-level functionality for Exchange.
Additionally, exposing a NAS to the hypervisor, and then sharing it out to Ex-
change 2013 as a storage medium doesn’t work.
3.Avoid using differencing storage mechanisms. This is especially true for
snapshotting and differencing Virtual Hard Disks (VHDs) in Microsoft Hyper-
V. The problem with snapshots and differencing VHDs is that they never com-
pletely capture the entire state of a given Exchange installation, which is often
spread out across multiple storage devices at once.
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
2 4 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
4EXCHANGE SERVER
Snapshotting an Exchange installation and then attempting to roll it back
might create inconsistencies across the various databases, with a broken
Exchange installation as a potential end result. Until Hyper-V’s snapshotting
becomes application-aware—which I don’t foresee for a while—you should
avoid using differencing VHDs or snapshots in virtualized Exchange 2013.
4.Allocate enough space for each virtualized instance of Exchange. For each
instance of Exchange to be virtualized, Microsoft recommends allocating disk
space using the following formula: “15 GB plus the amount of virtual memory
allocated to the VM in question.”
Therefore, a VM with 32 GB of RAM would need at least 47 GB of disk space
for the OS, the paging file and Exchange 2013’s own files. If you can throw more
space at the problem, go for it, but this is the bare minimum.
This space does not include Exchange’s databases; it’s just the minimum
amount of space required for Exchange 2013 plus the OS. Databases should
always be on a separate volume anyway.
5.Your Exchange 2010 storage plans should still work. When prepping for Ex-
change 2013 storage, remember that Microsoft recommends roughly the same
planning requirements that were laid out for Exchange 2010. If you still have
the storage calculator numbers you used to plan your Exchange 2010 setup,
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
2 5 V I RTUA L I Z I N G M I S S I O N - C R I T I CA L A P P L I CAT I O N S
4EXCHANGE SERVER
they should still prove useful. That said, any plans devised under earlier edi-
tions of Exchange Server should be revamped, especially if you’re performing
a physical-to-virtual migration.
FINAL THOUGHTSThe points discussed above indicate a number of possible future changes for how
Exchange 2013 storage will be handled when virtualized on Hyper-V. The most
important takeaway here is how Hyper-V could be made application-aware to al-
low snapshotting of Exchange instances.
That said, the scenarios where this functionality would be useful don’t involve
Exchange itself but are experiments involving Exchange indirectly. For example,
think of multiple iterations of the same setup to gauge differences between them.
Right now, Hyper-V supports more than enough of the functionality you need
to create and maintain a solid instance of Exchange 2013, as long as you keep in
mind the rules for allocating storage for both the hypervisor and Exchange Server
itself. —Serdar Yegulalp
Home
Editor’s Note
Designing a Mission-Critical Infrastructure
Virtual Appli-cation Perfor-
mance Testing: An Art Form
The Pros and Cons of
Virtualizing SQL Server Environ-
ments
Exchange 2013 Storage Consid-erations When Virtualizing on
Hyper-V
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ABOUTTHE
AUTHORS MARK VAUGHN (MBA, VCP, BEA-CA) serves as an enterprise architect for a multinational corpo-ration. Vaughn has more than 14 years of experi-ence in IT as a Unix administrator, developer, Web hosting administrator, IT manager and enterprise architect. Vaughn is a recipient of the 2009 vExpert award and has delivered several presentations at VMworld and BEAWorld confer-ences in the U.S. and Europe. Read his blog at http://blog.mvaughn.us.
MIKE NELSON has been in IT for more than 20 years, with exposure to a diverse field of technolo-gies and solutions. He has devoted more than half a decade to virtualization and server-based com-puting. Currently, Nelson is a senior analyst at a Fortune 100 company in the U.S. Midwest.
BASIT FAROOQ is a lead database administrator, trainer and technical author. He has more than a decade of IT experience in development, technical training and database administration on Micro-soft SQL Server platforms. Farooq has authored numerous SQL Server technical articles. He has also developed and implemented many successful database infrastructure, data warehouse and busi-ness intelligence projects.
SERDAR YEGULALP has been writing about per-sonal computing and IT for more than 15 years for a variety of publications, including Windows Magazine, InformationWeek and the TechTar-get family of sites.
Virtualizing Mission-Critical Applications is a SearchServerVirtualization.com
e-publication.
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