Server Virtualization

What is Server Virtualization –

Server virtualization is nothing but a method of running multiple independent (virtual) operating systems on a single physical server. Server virtualization masks server resources including the number and identity of individual physical server, processors and operating systems from server users.
The server administrator uses a software application to divide one physical server into multiple isolated virtual environments

The most popular approach to achieve server virtualization is through the way of creating virtual machine on a physical server. Each guest runs on a virtual imitation of the hardware layer. This approach allows the guest operating system to run without modifications. It also allows the administrator to create guests that use different operating systems. The guest has no knowledge of the host's operating system because it is not aware that it's not running on real hardware. It does, however, require real computing resources from the host -- so it uses a hypervisor to coordinate instructions to the CPU. The hypervisor is called a virtual machine monitor (VMM). It validates all the guest-issued CPU instructions and manages any executed code that requires addition privileges. VMware and Microsoft Virtual Server both use the virtual machine model.

Hosted Vs Native Virtualization –

Native/Hypervisor : (e.g. VMware ESX Server) – ESX is server is installed on x86 hardware. Multiple VMs can be installed on the top of ESX server. VMware provides various tools and service console to manage and monitor VMs.

Hosted: (e.g. VMware Workstation, VMware Player, VMware Server, ACE) Workstation/GSX Server is installed on the Windows/Linux OS having x86 hardware underneath. Virtualization installs like an application rather than like an operating system. This can run alongside conventional applications.


Benefits of Server Virtualization –

You can deploy multiple operating system technologies on a single hardware platform (i.e. Windows Server 2003, Linux, Windows 2000, etc).

Lower number of physical servers - reduced hardware maintenance costs because of a lower number of physical servers.

Server consolidation strategy increases the space utilization efficiency in your data center.

By having each application within its own "virtual server" you can prevent one application from impacting another application when upgrades or changes are made.

You can develop a standard virtual server build that can be easily duplicated which will speed up server deployment.


How to do Server Virtualization –

Physical to virtual server migration (e.g. VMware Converter)

This can be done with the help of P2V (Physical to Virtual) migration tools. The P2V tool will take an existing physical server and make a virtual hard drive image of that server with the necessary modifications to the driver stack so that the server will boot up and run as a virtual server. The benefit of this is that you don't need to rebuild your servers and manually reconfigure them as a virtual server—you simply suck them in with the entire server configuration intact!
So if you have a data center full of aging servers running on sub-GHz servers, these are the perfect candidates for P2V migration. You don't even need to worry about license acquisition costs because the licenses are already paid for. The annual hardware maintenance costs alone on the old server hardware would be enough to pay for all of the new hardware. Just imagine how clean your server room would look after such a migration. It would all fit inside of one rack and give you lots of room to grow.
As an added bonus of virtualization, you get a disaster recovery plan because the virtualized images can be used to instantly recover all your servers. With virtualization, you can recover the Active Directory and Exchange Server in less than an hour by rebuilding the virtual server from the P2V image.

Create new virtulialized infrastructure -

Using VMware products like ESX Server, VMware Virtual Center


Licensing And Support Considerations –

Software licensing models are being derailed by virtualization and multicore processors. Alternative licensing schemes range from the familiar, like open source and SaaS, to untested models like pricing based on memory or virtual cores. Most server software is still licensed per socket or per CPU, which essentially mean the same thing. The reasoning is simple: Chips are easy to count and unlikely to change during the life of a server, and these licenses give IT a strong incentive to use the most powerful multicore chips available. But then, getting the most out of software has always required high-performance hardware. The only difference is that Intel and Advanced Micro Devices are now more likely to boost performance by increasing cores than increasing megahertz.
Per-chip licensing makes sense for software that runs on clearly defined hardware. This used to mean every OS and most apps, but virtualization changes all that by adding a hypervisor that shields the OS from the underlying hardware. VMware has also adopted per-socket licensing, as has Virtual Iron. Following its acquisition by Citrix Systems, open source hypervisor vendor XenSource has moved to a per server licensing model. [1]
Microsoft treats each VM as a physical server with the same number of sockets as the underlying hardware. On its own, this would be a powerful deterrent to virtualization. Higher-end versions of Windows Server 2003 include licenses for extra virtual instances of the software on the same CPU--one on the Standard Edition, four on the Enterprise Edition, unlimited on the Datacenter Edition. The same will apply to Windows Server 2008. All Microsoft server licenses also include downgrade rights, meaning a virtual instance can be replaced by Windows 2000 or Windows NT.
Although Microsoft announced that it would unbundle the Hyper-V technology from Windows Server, a change from its previous claims that Viridian is an integral part of Windows Server 2008, the two are still designed to work together, and customers who choose to buy the server without it save only $28. Hyper-V represents a challenge to VMware; Microsoft already competes with hypervisors through Microsoft Virtual Server 2005, a free tool that can run other operating systems on top of Windows Server 2003, rather than alongside it. At present, however, Virtual Server supports only Windows as guest OSes, though Microsoft has said it will support SUSE Linux.
BEA Systems is thus far the only vendor to abandon per-socket licensing, albeit only for LiquidVM, a virtualized Java platform that cuts out the OS and runs directly on VMware. LiquidVM is licensed per instance, regardless of whether a VM runs in a few spare CPU cycles or consumes all the resources in a cluster. This model looks relatively easy to game and likely will be attractive to very large customers. IBM and Oracle Corporation have moved in the opposite direction from BEA, counting individual CPU cores.
Subcapacity licensing can result in savings, but only if VMs are tightly constrained to a limited number of cores. Problem is, the greatest selling point of virtualization is its flexibility, enabling capacity to be moved around between VMs as loads demand. To take advantage of this attribute, every application needs to be licensed for every core that it might run on, something IBM admits will entail higher costs for most customers.
Oracle's licensing is simpler than IBM's, based on counting cores as fractions of a processor, but it's less virtualization-friendly. An Oracle database running on VMware must be licensed for every core on the underlying hardware--regardless of how many cores the VM actually runs on. At present, the only way to save on Oracle licensing through virtualization is to limit the processor cores available to a database through Solaris Containers, which Oracle sees as placing tighter limits than VMware when it comes to restricting the number of cores available to an application.
With virtualization and multiple cores making per-server pricing obsolete, vendors are taking a look at several alternative schemes. The most well-known is metered pricing, which isn't new at all--IBM has offered it on mainframes for more than 40 years, and it still accounts for 10% of all IBM's software revenue. The model is generally more akin to a cell phone plan than strict metering: A fixed fee includes a certain amount of computing power, with customers paying extra when this cap is exceeded. It also isn't limited to software, as the bill is for the underlying hardware, too.
Before it was acquired by Oracle, PeopleSoft had the most egalitarian system, a proprietary equation that accounts for a customer's industry, head count, and revenue.
Most Linux distributions now include a Xen hypervisor, but vendors are split on how they handle licensing for instances that run on top of it. Novell lets customers run any number of instances inside VMs, with payment based on the underlying number of CPUs. Red Hat follows the same model as Sun, requiring a separate license for each installation unless customers use its built-in virtualization technology.


References –
http://vmware.com
http://en.wikipedia.org/
http://articles.techrepublic.com

Virtualization - Basics of CLOUD

Let's follow the top to bottom approach to understand basics in virtualization.Currently as on date, latest buzz in this domain is 'CLOUD’. Talked by most of the key players i.e. VMware,IBM,Google, Amazon let's see what is this all about.

I am sure it this topic will explain the topic with fun just like 5 year school going child.

Thanks to the existing source at you tube.

Top 10 Techies

10 tech people you should know.

http://www.networkworld.com/supp/2009/outlook/010509-tech-people-to-know.html?page=1