Virtual Appliances — Refining Virtualization

We all know that virtualization is the biggest wave in computing ever occurred. Many organizations are adopting virtualization as a preferred choice for computing and infrastructural environments. Virtualization itself is emerging with new trends everyday.

In this post we will walk through one of the interesting virtualization technique called as Virtual Appliance.

What Wikipedia Says of Virtual Appliance:

A virtual appliance is a minimalist virtual machine image designed to run under some sort of virtualization technology (like VMware Workstation, Citrix XenServer, VirtualBox or many others).

Virtual appliances are a subset of the broader class of software appliances. Like software appliances, virtual appliances are aimed to eliminate the installation, configuration and maintenance costs associated with running complex stacks of software.

A key concept that differentiates a virtual appliance from a virtual machine is that a virtual appliance is a fully pre-installed and pre-configured application and operating system environment whereas a virtual machine is, by itself, without application software.

Typically a virtual appliance will have a web interface to configure the inner workings of the appliance. A virtual appliance is usually built to host a single application, and so represents a new way of deploying network applications.

As an example, the MediaWiki software that powers Wikipedia is available as a virtual appliance. This appliance contains all the necessary software, including operating system, database and MediaWiki, to run a wiki installation as a “black box”.

Here are some useful links which can be useful to you:

• Wikipedia Page.
• VmWare’s repository of Virtual Appliances
• Linux.com :: A virtual appliance primer
• Virtual Appliances Home

Virtual Appliances – Next generation applications

del.icio.us Tags: Virtualization,Xen,VMware,Linux

A virtual appliance is a minimalist virtual machine image designed to run under any virtualization technology.

A key concept that differentiates a virtual appliance from a virtual machine is that a virtual appliance is a fully pre-installed and pre-configured application and operating system environment whereas a virtual machine is, by itself, without application software.

Typically a virtual appliance will have a web interface to configure the inner workings of the appliance. A virtual appliance is usually built to host a single application, and so represents a new way of deploying network applications.

JeOS — Just Enough Operating System

We have seen significant growth in size and complexity of general purpose OS over a last decade.  This expansion has come from its need to support a growing number of applications and devices.  To support the increasingly complex needs of this myriad of applications, OS vendors have added more interfaces, libraries, and functions with each release.  As a result, operating systems have grown like balloon, becoming bloated, complex, and far less secure.  Most operating systems now require at least 1 GB of RAM just to run because of the various necessary and unnecessary services that are loaded into memory, as well as a few GB of disk space.  Because the foot print is huge, keeping the OS and your data center secure requires that it be patched more often than ever before.

Most servers today run just a single application – one web server or one print server or one Exchange server – but never multiple applications all at once on the same OS instance.  The question then is, if you run just one app per server, wouldn’t it make more sense to have only the OS components needed for that app rather than a general purpose OS that is slow, less secure and hard to manage?  Do you really need a Graphics Driver on your Exchange server?  Do you really need all those services that are running in memory?

Xen Live Migration

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Virtual machine migration can be thought of as a special form of suspend/resume, in which the state file is immediately transferred and resumed on a different target machine. Migration is particularly attractive in the data center, where it allows the current workload to be balanced dynamically across available rack space.

However, although Xen’s suspend/resume mechanism is very efficient, it may not be suitable for migrating latency-sensitive or high-availability applications. This is because the virtual machine cannot resume execution until its state file has been transferred to the target system, and this delay is largely determined by its memory size: a complex VM with a large memory allocation takes a correspondingly long time to transfer.

Xen for you and for me.

Xen, a relatively new open source project that turns one piece of hardware into many, virtually. If you’re looking to cut costs or maximize usage or both, follow the path to Xen.

Up until now, there have been no open source solutions for efficient, low-level virtualization of operating systems. But now there’s Xen, a virtual machine manager (VMM) developed at the University of Cambridge.

Xen uses a technique called paravirtualization, where the operating system that is to be virtualized is modified, but the applications run unmodified. Paravirtualization achieves unparalleled performance, while still supporting existing application binaries.

The Second Generation Virtualization with Xen

What is Virtualization?

The concept of virtualization has existed in one form or another in computing since the early 1960s. In virtualization, the characteristics of a resource are abstracted, so that it may be accessed in some way that is different from its actual physical form.

What are Virtual Machines?

System virtualization (often “server virtualization” or “desktop virtualization,” depending on the role of the virtualized system) is the ability to present the resources of a single computer as if it is a collection of separate computers (“virtual machines”), each with its own virtual CPUs, network interfaces, storage, and operating system.

Virtualization – Thinking beyond multitasking.

Virtualization is the term which is widely used across many areas but in this post we are going to look into Virtualization from computing perspective.

Virtualization means creating virtual instances of something. From the computing perspective it refers to the process of creating virtual instances of computer based system.

Though there are many faces of virtualization in computing also, we will mainly focus on Operating System Virtualization.