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VIRTUALIZATION
May 2007 |
Virtualized
versus traditional blade platforms Server consolidation has become a key strategy for reducing data center costs. by Blaine Kohl Maximizing the
efficiency of data centers and providing high-availability computing
services to organizations means increasing performance while minimizing
costs and reducing power budgets. Various mechanisms can help IT departments
accomplish these goals, but one that is rapidly increasing in popularity is
virtualization. Virtualization lowers operating expenses by reducing IT
labor costs through simpler configuration setups, decreases electrical
expenses, and frees up costly floor space. In addition, virtualization can
be employed via the operating system and/or hardware implementations.
Typical server
deployments average $10,000 per server. Server network utilization averages
between 10 percent and 15 percent, and CPU utilization rarely exceeds 10
percent. In addition, more servers frequently result in the need for a
larger IT staff and increased network complexity.
If an IT professional’s
pay averages $40 per hour and each server deployment requires up to 30 staff
hours to complete, approximately $1,200 in labor costs alone can be reduced
for each server that is eliminated via consolidation. This savings is in
addition to the savings seen in reduced physical hardware expenses.
Many enterprises
experience high hardware costs due to running one software application per
server. For example, an entire server may be used for a print-server
application or a file-sharing server application. Application multitasking
on a single, traditional dedicated server, however, is risky, because if the
print server crashes it could also cause the file-sharing server to crash,
as well. On the other hand, dedicating one server per application
contributes to poor CPU and network utilization rates.
A virtualized
deployment can consolidate those dedicated servers into one physical server.
Server virtualization is the masking of server resources, including the
number and identity of individual physical servers, processors, and
operating systems, from server users. The server administrator uses either a
software application or dedicated hardware to divide one physical server
into multiple isolated virtual environments. Virtual environments are
sometimes referred to as virtual private servers, virtual machines (VM) or
operating system domains (OSD).
A significant cost
savings stems from a virtualized deployment requiring far fewer physical
servers than a traditional enterprise deployment by moving physical
application servers onto a virtual machine running on a host or virtualized
blade. In real world cases, the consolidation ratio typically averages 10
virtual servers per physical machine.
The reduction in the
number of physical servers saves real estate space, lowers electrical bills
and saves on cooling expenses. Additionally, management tasks can be
automated and controlled from a single console. Maintenance also becomes
easier as virtual machines have the ability to be shut down, transferred
across the network to a new physical server and brought up within seconds.
By reducing the number
of servers, the number of hardware configurations is also reduced;
therefore, software patches and upgrades become easier to manage. Server
load balancing can be automated from a single point rather than by
monitoring each server independently, allowing for better utilization of the
corporate assets. Additionally, network bandwidth often improves in a
virtualized environment as hardware can now fully utilize 10-Gigabit
Ethernet (10GbE). While in a traditional deployment, each application server
would not likely utilize 10GbE bandwidth, the aggregation of the virtualized
servers can fully utilize the available network speed, leaving room for peak
scenarios.
There are incremental
costs associated with a consolidation of servers in the data center,
including the virtualization machine software, network interface cards (NIC)
and cabling. This is a fraction of traditional implementations, however,
when compared to the potential savings of 10 servers for every one
consolidated.
VM software inserts a
thin layer of software between the operating system (OS) and the underlying
server hardware. This layer, known as a virtual machine monitor (VMM) or
hypervisor, is responsible for allowing multiple OS images and their running
applications to share the resources of a single host server and allows
multiple operating systems to run at the same time. Each OS appears to have
the resources of the entire machine under its control, but beneath it, the
hypervisor transparently ensures that resources are properly and securely
shared between different OS images and their applications.
Virtualization allows
each virtual machine to be isolated from the physical system by creating
virtual processors, interrupts and devices. By doing so, no single virtual
machine can cause a system fatal error; at worst, it can compromise only the
individual virtual machine. Therefore, if the print server should crash,
there will be no impact to the Web server or the file-sharing server running
on the same physical hardware server. This allows mission-critical
applications to be shared on a single physical server with no compromise to
availability.
In addition to software
virtualization, hardware virtualization is possible. One of the newer
implementations gaining a lot of interest is the work being done by the PCI
Express special interest group regarding IO virtualization and multiroot
shared I/O.
The shared I/O approach
maximizes I/O utilization in a blade chassis. In traditional blade
configurations, a network interface card is
required for each blade unit to drive network traffic. When IT
administrators consolidate server blades, they are reducing the number of
touch points to the network, which also reduces the blade platforms’ overall
network throughput.
An alternative approach
allows a single shared 10GbE network controller to be shared by several
blades simultaneously in a 10GbE environment, yet retains its simplicity as
well as advantages such as independent operating systems on each blade.
Incremental blades added to a platform can be significantly less expensive,
as there is no need to purchase additional blade network adapters.
Additionally, performance is able to reach near line-rate speeds, while the
complete blade configuration can be up to $10,000 less expensive to deploy.
Blaine Kohl is vice president of marketing for Tehuti Networks, Austin,
Texas.
For more information from
Tehuti Networks: |