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Server Virtualization on Microsoft Servers
Every enterprise can benefit from improving the
utilization of IT resources. Improved utilization not
only helps reduce costs but can also simplify IT
infrastructure, leading to reduced operations costs.
A virtual computing infrastructure can provide the
features that enable these benefits. At the same time,
a virtual infrastructure can heighten the availability of
mission-critical applications and improve IT agility to
respond to business needs. Virtuozzo* software provides
a high-performance, low-overhead environment for
virtual computing infrastructures; the low overhead on
Virtuozzo makes it ideal for I/O-intensive applications
such as databases. To maintain the reliability,
flexibility, and performance that a high I/O virtual
infrastructure provides, physical servers hosting
virtual machines need multiple, high-throughput
network connections. This is an ideal environment for
the use of connection-dense Intel® PRO/1000 multiport
gigabit and Intel® PRO/10GbE 10-gigabit Ethernet
network adapters.
White Paper
Virtualization Addresses Key Challenges
Facing IT Today
IT organizations everywhere face daily challenges: Do more
with less. Respond to new initiatives faster. Reduce downtime.
Sound familiar? A growing number of enterprises are finding
that server virtualization is a proven way to better utilize
equipment, keep management, administrative, and overhead
costs in check, improve availability of resources, and provide
a flexible infrastructure that accommodates rapid change to
business needs.
Increased server utilization improve s return on
investment
Due to a one-application-per-server deployment philosophy,
most distributed servers operate at low levels of utilization.
Virtualization enables the workload from multiple servers to
run on the same physical server node, taking advantage of
that unused processing power. Virtualization makes existing
server resources available for doing more work, which allows
you to get more done with what you already have. Each virtual
machine provides an isolated operating environment for use by
applications and users. A server virtualized in this way can be
60 to 80 percent utilized, which is expected to lower the server
investment required to handle a given amount of work.
Virtualization lowers tota l cost of ownership
In addition to reduced capital costs, the fewer physical servers
and reduced data center complexity required by virtualization
can also reduce administrative costs. Virtualized server
management tools can contribute to improved administrative
productivity. With a small set of server management tools that
are standardized across the enterprise, training costs can be
reduced. Also, fewer servers can reduce the IT infrastructure
footprint and associated utility costs for power and cooling.
A virtualized infrastructure improve s application
avai lability
Application availability is essential to ongoing missioncritical
operations. Server virtualization helps keep business
operations running smoothly by providing the tools to migrate
a virtual machine to a different physical host with a service
interruption of only a few seconds—eliminating hours of
downtime when planned maintenance needs to be performed.
In the case of an equipment or application failure, a virtual
machine on another physical host can be provisioned and
started in minutes. Backup data can be restored to the new
session quickly, minimizing downtime.
The result is increased application availability, as application
outages in a virtualized environment are reduced to minutes
or hours instead of days.
Virtualization ena bles busine ss agilit y
Virtualization initiatives enable a server infrastructure that
can be very quickly modified to meet changing business
needs or help address new opportunities. Virtualized servers
can be provisioned quickly—usually in minutes instead of
days—to handle peaks in demand. This ability is crucial when
workloads (such as Web-based applications) are unpredictable
and business operations need to respond in a rapid manner.
Introducing Virtuozzo*
Virtuozzo from SWsoft is server virtualization software that
makes very efficient use of hardware and operating system
(OS) resources. Virtuozzo employs a technology known as OS
virtualization to define, configure, and operate multiple virtual
private servers (VPSs) in a single hardware node, as shown in
Figure 1.
Virtuozzo is available for Microsoft Windows Server* 2003 and
multiple Linux* distributions, and runs on platforms based on
Intel® Pentium® processors, 64-bit Intel® Xeon® processors, and
Intel® Itanium® 2 processors. Virtuozzo supports multiprocessor
configurations with up to 32 processors and 64 GB of memory.
The virtualization technique employed by Virtuozzo (see sidebar
on page 3) uses a single, unmodified image of the OS to host all
VPS sessions. This approach offers several additional advantages
when compared to other approaches to virtualization, including:
• Extended platform compatibility. Virtuozzo has the same
platform compatibility as the host OS and can operate on any
hardware supported by the OS. No modifications are required
for applications deployed on Virtuozzo. Only one image of the
OS is needed for each node, regardless of the number of VPS
instances running on the node.
Rapid provisioning. Virtuozzo instantiates a VPS session
in several seconds because the underlying OS is already
running. This enables rapid provisioning of underutilized
server infrastructure.
Virtuozzo Adds to the Benefits of
Virtualization
When used in a data center virtualization initiative,
Virtuozzo provides additional benefits in the areas of
processor efficiency, operational cost reductions, application
availability, and dynamic administration features.
Virtuozzo is highly eficient
The lightweight virtualization architecture that Virtuozzo
is built upon incurs little overhead. An application running
within a Virtuozzo VPS typically exhibits between 1 to 3
percent performance overhead when compared to a native,
nonvirtualized application. The low performance overhead
enables I/O-intensive applications such as databases to
perform well in virtualized instances. This very low overhead
(in essence, processor cycles spent to provide a virtualized
environment) means that compute resources are devoted to
application workloads, users, or additional VPS instances—
not the process of virtualization.
Virtuozzo can reduce virtualized server
ownership costs
Virtuozzo can reduce costs in several ways. Since OS
virtualization uses a single operating system image, software
licensing costs are minimized. Virtuozzo also offers a
complete set of management capabilities that enable singleconsole
control of all virtual servers on all nodes by an
administrator, eliminating the need to visit every virtual
server to perform administrative tasks. This ability can
reduce the amount of time spent (and thus, costs incurred)
by IT staff on routine system management activities.
Zero-Downtime Migration increases avai lability
Situations such as routine hardware or software maintenance
often necessitate moving a virtualized application from
one physical server to another. Typically these types of
maintenance activities or migrations are scheduled for nonwork
hours, but Virtuozzo provides the capability to move
an available VPS to another physical server without any
interruption in service or availability. The Virtuozzo Zero-
Downtime Migration is unique among virtualization products
because it does not require any storage area network (SAN)
investment—this capability can be used on any Virtuozzo
server, associated VPSs, and applications at any time.
Compact data model reduces resto re time, provi ding
a cost-efective disaster recove ry solution
Should an unanticipated event occur and render the host
node unavailable, an online backup can quickly provide
the source data for restoration to a functioning VPS on
a different node. A Virtuozzo VPS backup contains the
applications running on the VPS, application data, any files
that are required by the applications, and user data. There
is no need to restore the OS itself, since a functioning OS
is present on the target VPS. This reduces the amount of
data that needs to be transferred, and thus the time needed
to perform the restoration of a VPS. A shorter recovery
period means that application downtime is minimized. The
use of shared storage architecture (such as a storage area
network or network-attached storage devices) can be used
to replicate servers and provide an always-available disaster
recovery solution, although Virtuozzo does not require the
use of shared storage.
Management to ls provi de comprehensive dynamic
control
Virtuozzo includes a full set of management tools that
provide real-time creation and control of any VPS on any
node running any operating system supported by Virtuozzo,
all from a single console. Thus, an administrator can manage
both Microsoft Windows* and Linux environments using a
single tool. Provisioned VPSs can be started very quickly in a
Virtuozzo environment—usually in seconds because the OS is
already running.
Once a VPS is operating, the Virtuozzo Management Console (see
Figure 2) allows administrators to dynamically allocate individual
VPS resources (amount of VPS server memory, disk space,
processor time, and so forth) without service interruption. This
capability gives system managers granular, real-time resource
control, resulting in increased infrastructure agility without
requiring a shutdown of the VPS or the entire hardware node.
A VPS can also be copied, or cloned, in real time via the
management console. Cloning a VPS can be useful in a
development or a production testing environment to observe
the effects of a software upgrade or update on regular server
operation.
A Virtualized Environment Requires a
Reliable, High-Capacity Network
To successfully consolidate server workloads onto a virtualized
environment, it is essential that all server subsystems
(processor, memory, disk, and I/O) can accommodate the
additional workload. While Virtuozzo requires a single network
connection to operate, careful attention to and planning of
the networking infrastructure of a Virtuozzo environment can
ensure both optimal performance and high availability.
Multiple VPSs increase network trafic
With multiple workloads, the network capacity needs
to scale to match the requirements of the combined
workloads expected on the node. In general, as long as
the node’s processor is not fully utilized, the consolidated
network traffic will be the sum of the traffic generated
by each application. For example, if five physical servers
using an average of 30 Mbps of bandwidth and running at
15 percent utilization are consolidated, then the Virtuozzo
host machine running the five VPSs requires roughly 150
Mbps of bandwidth. Therefore, a network connection
running at 100 Mbps will not adequately service such a
configuration, and a higher-capacity network interface
is necessary.
Very high bandwidth is desirable during migration s
and resto ration s
While a VPS can be created and started in minutes, any
migration or restoration operation requires time to transfer
all of the data from the source to the target. Network
throughput is directly related to the time it takes to copy
the data to a new VPS on a different hardware node. VPSs
can have gigabytes of data to transfer, and the faster this
data can be copied over the network, the more rapidly the
operation can be completed—especially in the case of a
migration or a restoration.
Host node reliability is critical
With multiple virtual machines running on a single node,
the reliability of that node becomes much more important.
Likewise, redundancy and fault tolerance are critically
important for network infrastructure. The failure of a
connection supporting a node could affect every user of
every VPS running on the node—a costly interruption that is
time-consuming to fix. Providing an alternate network path
through a meshed switch fabric and using multiport adapters
that support failover can mitigate that risk and improve
overall reliability and availability.
All of these considerations point to designing a virtualized
infrastructure’s networking subsystems with the capacity
and availability features delivered by multiple high-capacity
network connections. This can be challenging if servers are
peripheral component interconnect (PCI) slot-constrained.
Small 1U servers acting as host nodes have limited expansion
capability. Incorporating multiple network interfaces helps
make such servers more reliable and available, as well as
better able to handle the increased traffic.
Intel® Network Adapters Offer
Performance, Flexibility, and Reliability
for VPS Deployments
The Intel® PRO/1000 family of network adapters and the
Intel® PRO/10GbE 10-gigabit adapters meet the performance,
flexibility, and reliability needs of host nodes in connectiondense
Virtuozzo environments. In particular, the dual- or quadport
Intel PRO/1000 multiport adapters provide the needed port
density for use in slot-constrained server platforms.
Performance
The Intel® PRO/10GbE SR and Intel® PRO/10GbE LR Server
Adapters offer exceptional throughput and some of the
fastest Ethernet connectivity available. Both adapters feature
jumbo frame support of up to 16 KB, which reduces packet
overhead for increased performance. To reduce processor
involvement with the processing of network traffic, each
adapter has mechanisms to delay and reduce transmit and
receive frame interrupts, as well as TCP/IP segmentation and
TCP checksum off-load. Intel PRO/10GbE network adapters
offer the throughput necessary for VPS restorations or
migrations—when time is of critical importance and very
high throughput is a requirement.
To meet the needs for multigigabit traffic, the Ethernet
ports on the Intel PRO/1000 family of multiport adapters
can be aggregated to deliver greater total bandwidth. Server
performance can also be enhanced by teaming connections
on adapters with connections on other Intel® PRO Server
Adapters or with LAN on Motherboard components to achieve
the desired scalability. Throughput counts during a VPS
restore operation; the faster data can be transferred to the
new VPS, the sooner the VPS can be placed in operation.
At very high data rates, network traffic can take a toll on
server processor cycles. All Intel PRO/1000 Server Adapters
feature interrupt moderation, which significantly reduces
processor utilization and makes more processor resources
available to applications.
To increase performance in a multiprocessor environment,
the Intel® PRO/1000 PT Server Adapter can balance network
loads across processor cores when used with Receive-
Side Scaling from Microsoft or Scalable I/O on Linux,
environments both supported by Virtuozzo.
Learn More about These Virtualization
Products
For more information about the products described in this
white paper, visit www.virtuozzo.com or www.intel.com/
network/connectivity.
About SWsoft
SWsoft is the recognized leader in OS server automation and
virtualization software. The SWsoft suite of products delivers
proven performance, reliability, manageability, and value.
Headquartered in Herndon, Va., with offices around the
world, SWsoft is a privately held, high-growth company.
For more information, visit www.virtuozzo.com or call
+1 (703) 815-5670.
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