Basics of Virtuallization

What is Virtualization?

Virtualization is a general and ambiguous term that typically means to run multiple instances of something inside something that was intended to only run a single instance.

Virtualization is the creation of a virtual operating system, a server, a storage device or network resources. (rather than actual) version of something, such an operating system, a server, a storage device or network resources.

Operating system virtualization is the use of software to allow a piece of hardware to run multiple operating system images at the same time. The technology got its start on mainframes decades ago, allowing administrators to avoid wasting expensive processing power.

• Network virtualization is a method of combining the available resources in a network by splitting up the available bandwidth into channels, each of which is independent from the others, and each of which can be assigned (or reassigned) to a particular server or device in real time. The idea is that virtualization disguises the true complexity of the network by separating it into manageable parts, much like your partitioned hard drive makes it easier to manage your files.
• Storage virtualization is the pooling of physical storage from multiple network storage devices into what appears to be a single storage device that is managed from a central console. Storage virtualization is commonly used in storage area networks (SANs).
• 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 intention is to spare the user from having to understand and manage complicated details of server resources while increasing resource sharing and utilization and maintaining the capacity to expand later.

How do we get virtualization?

Well there is no. of options available for this, but VMware, Citrix and Microsoft are front runners in domain. Here are the products from above for the same.

1. VMware ESX and VMware server
2. Citrix Xen
3. Microsoft Hyper-V

VMware Server:

VMware Server is a free virtualization product for Microsoft Windows and Linux servers. It enables you to quickly provision new server capacity or server consolidation by partitioning a Physical server into multiple virtual machines. It is meant for those businesses who want to optimize use of their technology assets using virtualization.

Technology behind VMware Server:

• Hypervisor – 2 (Hosted Architecture)

What is Hosted Architecture?

Hosted architecture is where your virtualization software is installed as an application onto the pre-existing host operating system. This means that your virtualization layer relies on your host operating system for device support and physical resource management. VMware Server is a good example of a hosted architecture.

Hardware and Software support:

1. Any standard x86 compatible or x-86-64compatible personal computer
2. A wide variety of Windows, Linux, Solaris, and other guest operating systems,

Including 64-bit operating systems

3. Two-way Virtual SMP
4. Intel Virtualization Technology (Intel VT)
5. AMD-Virtualization (AMT-V)

Where VMware Server does fits for your environment?

VMware server suits the requirements and demands of small and medium scale business with non-mission critical processes. It can provide following options to the business resources.

1. Virtual Machines for software development:
1. A common environment matching in both configuration and tools for your entire team
2. Quick rollout of new environments and tools
3. Archive of entire development environments for major projects

2. Virtual Machines for software testing:
1. Platform Testing with Snapshots
2. Platform Testing with Persistent and Non-persistent Disks

3. Virtual Machines for Post-release and Application-Maintenance.
1. It can create base image for you development environment
2. Archive of the development team’s virtual machines used during the development phase
3. Rapid platform availability for quick support tasks and bug investigation

4. Run Windows, Linux, and other operating systems and applications without

Software conflicts.

5. Move virtual machines from one physical host to another without having to

Reconfigure them.

Features of VMware Server:

1. Web-Based Interface

Use VMware Infrastructure Web Access (VI Web Access) to perform host and virtual machine configuration for VMware Server 2.0.

1. Create, configure, and delete virtual machines
2. Add and remove virtual machines from the inventory
3. Perform power operations (start, stop, reset, suspend, and resume) on virtual Machines
4. Monitor the operation of virtual machines
5. Generate a Web shortcut to customize the VI Web Access user interface for users, with the option to limit their view to the console or a single virtual machine
6. Generate a VMware Remote Console desktop shortcut that allows virtual machine users to interact directly with the guest operating system outside of a Web browser
7. Configure host-wide VMware Server settings

2. VMware Remote Console

VMware Remote Console enables you to interact with the guest operating system

running in a virtual machine. You can run VMware Remote Console on the host or a remote client system. After you install it as a Web browser add-on from VIWeb Access, VMware Remote Console can run independently from VIWeb Access.

VMware Remote Console also allows you to connect and disconnect client CD/DVD

and floppy devices.

3. Memory Support

The maximum amount of memory that can be allocated per virtual machine is

8GB. The amount of memory that can be used by all virtual machines combined is limited only by the amount of memory on the host computer.

4. Number of Network Adapters Supported

It can support total of 10 network adapters for a virtual machine.

5. Quiesced Backups of Virtual Machines on Windows

On Windows hosts, you can enable the VMware VSS Writer, which uses snapshots to

maintain the data integrity of applications running inside the virtual machine when

you take backups.

6. Support for High-Speed USB 2.0 Devices

If the guest operating system has the appropriate USB 2.0 device drivers, you can use peripherals that require high-speed performance, such as speakers, webcams,

next-generation printers and scanners, fast storage devices, MP3 players, DVD-RW

drives, and high-capacity CD-ROM jukeboxes.

Besides above there are few more such as

· Additional host operating system support

· Additional guest operating system support

· improved 64 bit guest support

· 64 bit sound driver

· Native 64 bit support on linux

· Improved VIX-API

· VMCI socket interface

Bottlenecks:

1. It puts more of your client's eggs in one basket. If the host machine breaks or needs to be taken offline, several virtual servers will go down.
2. Applications like databases that require a lot of disk activity. The prevailing wisdom is that databases should still run on dedicated physical servers.
3. Time-sensitive applications like Voice over IP (VoIP) may also be poor candidates for virtualization.
4. Virtual Machine overload: Application that are low I/O intensive and low utilization are best candidates for virtualization but need to put restriction on no. of virtual machines that can be handled with ease on physical server.

VMware Server at a glance:

Architecture	Hosted
OS Requirements	Windows or Linux
Typical Use Cases	Test & Dev, Production
Dedicated Server Required	No
Centralized Management Option	No
Ease of Use	High
Performance	Good