Linux Containers Authors: Yeshim Deniz, Pat Romanski, Elizabeth White, Liz McMillan, Vaibhaw Pandey

Related Topics: Linux Containers

Linux Containers: Article

The Other Virtualization Technology... OS Virtualization

There's more than one way to skin a cat

Server virtualization is rapidly becoming a common undertaking for IT departments. As a matter of fact, many organizations are now taking the next step: evaluating their virtualization investment to see whether it's helped them achieve the server consolidation goals they previously set. And along the way many IT departments have had some surprises such as a "performance tax," a reduction in server or application performance as a result of virtualizing applications using hardware virtualization technology. With the advent of operating system virtualization, this evaluation process is starting to reveal that some deployments and uses are perfectly suited to hardware virtualization, while others are more suited to OS virtualization.

Using Hardware Virtualization
Hardware emulation or virtualization is probably the best-known virtualization technology. VMware and Microsoft both have product offerings that fit this class of virtualization (although the products themselves are quite different in functionality and maturity). Hardware virtualization technology creates a full emulation of hardware at the host OS level. Full emulation typically runs some part of the guest OS code on the native CPU, but some privileged instructions are emulated and handled separately. Besides the CPU, the software has to emulate the BIOS, video adapters, network adapters, storage, and input/output devices to provide a normal environment for the guest OS's operation. The extent of the emulation allows almost any existing OS to run inside the virtual environment. Each virtual environment (a generic term used across all technologies for virtual machines, virtual servers, and virtual private servers) has an entire OS structure, keeping all the software and processes completely isolated. The primary use of this technology has been to provide multiple different OSes on the same physical piece of hardware. Multiple OSes are, in particular, a requirement in development and testing scenarios, where engineers are developing software simultaneously on different operating systems. Many organizations have deployed hardware virtualization in full production scenarios as well.

Experimenting with Paravirtualization
The Xen Open Source project and various paravirtualization approaches have been hot technology topics over the past year. Paravirtualization is built on the same concepts as hardware virtualization, emulating hardware, and creating a server infrastructure for multiple OSes on the same server. The most important difference is that Xen optimizes the operating system to make some important improvements in performance - although that requires altering the operating system. Paravirtualization solutions are still only available in Open Source form, so they haven't been fully adopted or tested yet by many organizations. Xen also has a very limited set of tools, so managing these technologies can be cumbersome.

Exploring OS Virtualization
OS virtualization is an established virtualization technology that's now gaining significant interest and momentum in the marketplace. Quoted as the virtualization technology with the best potential for server consolidation by Gartner at its Data Center conference in December 2005, OS virtualization is now being evaluated and examined by many organizations new to virtualization, and many that have already deployed other virtualization technologies. The two primary OS virtualization solutions are SWsoft's Virtuozzo and Zones in Sun's Solaris OS. There are also several Open Source OS virtualization projects like OpenVZ and Vserver.

OS virtualization technology leverages a single common OS and creates separate, isolated virtual environments on a single physical server to share hardware and software efficiently. The two available technologies differ in their maturity, but the optimal design includes an architecture that ensures that there's complete isolation and security between each virtualized server. The overall design intent of OS virtualization is to produce a more flexible, lower-overhead virtualization option that uses a single operating system and leverages the hardware support built into the OS. OS virtualization technology results in reduced server and application overhead, better density without redundant OSes, and lower total cost of ownership. The primary use of OS virtualization technology is to deploy production application and data on live servers, although in the correct circumstances it's also quite effective for development environments.

A Choice for Server Consolidation?
What are the primary reasons most IT organizations are considering server virtualization and consolidation projects?

The list is long, but the primary reasons include controlling server sprawl, reducing the total cost of ownership, and increasing manageability. The following are some of the key considerations when deciding between hardware and OS virtualization approaches.

Hardware Virtualization for Server Consolidation
Many organizations have deployed hardware virtualization projects and have seen some improvements in server sprawl, but in some cases not as much as originally hoped. This is due to the performance penalty; heavy I/O and production applications often don't perform well enough in a virtualized environment to be deployed.

The total cost of ownership varies tremendously between the different hardware virtualization options. Not all hardware virtualization solutions are the same; the better-performing solutions with more management tool capabilities have a much higher price-premium than the entry-level solutions. The higher-priced solutions will offer better performance and higher virtualized server density, while the lower-cost solutions enable a bare amount of virtualization capabilities with a more severe performance tax. Initially, some organizations thought they might yield some savings in software, but the hardware virtualization architecture only yields savings in hardware by better utilizing server resources.

Finally, hardware virtualization has increased some server infrastructure manageability with its toolsets. Provisioning and centralized server management are areas of obvious improvement. The areas that haven't seen much improvement are the day-to-day management tasks associated with servers: upgrades, updates, and backups. Because each virtualized server is a complete and isolated server, the administrator still must manage each virtualized server as though it were a separate physical server. While the management toolsets can be helpful, they can't overcome the architectural management limitations.

OS Virtualization for Server Consolidation
The first consideration for server consolidation is addressing server sprawl. OS virtualization can potentially use a single operating system per server, while some technologies allow for multiple variations of operating systems. OS virtualization provides the leanest software overhead. Due to the efficient architecture, it has the best potential for virtualized server density and therefore the fewest total physical servers. OS virtualization installations can support virtualized servers a magnitude greater than a typical hardware virtualization deployment.

Due to both the single operating system structure and the lack of hardware emulation overhead, the performance of OS virtualization also outstrips the performance of hardware virtualization. The low overhead enables all applications, from databases to DNS servers, to be loaded and have near-native performance in a virtual server. More applications and servers are suited to OS virtualization and therefore more servers with various purposes and levels of applications can be consolidated safely.

Total cost of ownership is the main driver of the architecture and intent of OS virtualization. The sheer hardware savings achieved with the highly virtualized server density is just one component. The physical server itself requires just a single copy of the operating system, dramatically reducing the total cost of ownership through reduced software licensing costs. There is a perception that the single OS is a limitation, but certain OS virtualization technologies have taken great pains to ensure that these concerns are alleviated. Some technologies have built-in layers for isolation, security, and resource control that make the single OS approach very safe and controlled. Also, because the OS can be identified as a single point of failure, all virtualization approaches have a single point of failure, whether created by the vendor or in this case by an operating system vendor. Again, some OSes are perceived to have more security issues than a proprietary hypervisor, but some OS virtualization technologies have taken this into consideration too and use security layers to mediate kernel access and ensure that it's safe. In taking these precautions, OS virtualization can reap incredible benefits by using a standard OS, such as supporting any hardware that the OS supports, while minimizing risks and ensuring that virtualized servers are isolated and secure from one another.

Lastly, OS virtualization has the best potential for manageability improvements. The available technologies have varying levels of toolsets, but the most established toolset is very comprehensive. As with hardware virtualization, management improvements can be gained from fast provisioning and centralized server management. OS virtualization provisioning is even faster. As images or copies of operating systems aren't required, a very thin virtualized server structure is created in a matter of seconds. In addition, OS virtualization can be configured to have a single OS version loaded for the entire server. The single version enables an entire server to be updated and patched with a single action. Administrators can now manage several virtualized servers just as easily as managing a single physical server. Some of the technologies have additional capabilities such as cloning, zero-downtime migration, and backup, allowing virtualized servers to be tested on a new patch level if necessary, and then deployed in seconds. Some see the single patch level as a limitation of the OS virtualization technology, but this has also been addressed in some of the available technologies. Some technologies enable different distributions to be loaded on a single server in the case of Linux, and different patch levels on a Windows server. Loading different patch levels takes away from the lean intent and design, but it provides the real-world flexibility many organizations require.

Moving Forward
Many IT departments have already had very successful server virtualization deployments and are now looking for opportunities to gain even more benefits from this important technology. As options such as OS virtualization become more prevalent, more and more organizations will consider the architectures and approaches and deploy the appropriate technologies with the appropriate applications and virtualized servers. In some cases, virtualization technologies will replace each other, but more commonly, virtualization and consolidation strategies will become more finely tuned and matched with the appropriate technology.

More Stories By Carla Safigan

Carla Safigan is director of product management at Parallels Inc.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.

@ThingsExpo Stories
DX World EXPO, LLC, a Lighthouse Point, Florida-based startup trade show producer and the creator of "DXWorldEXPO® - Digital Transformation Conference & Expo" has announced its executive management team. The team is headed by Levent Selamoglu, who has been named CEO. "Now is the time for a truly global DX event, to bring together the leading minds from the technology world in a conversation about Digital Transformation," he said in making the announcement.
"Space Monkey by Vivent Smart Home is a product that is a distributed cloud-based edge storage network. Vivent Smart Home, our parent company, is a smart home provider that places a lot of hard drives across homes in North America," explained JT Olds, Director of Engineering, and Brandon Crowfeather, Product Manager, at Vivint Smart Home, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that Conference Guru has been named “Media Sponsor” of the 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. A valuable conference experience generates new contacts, sales leads, potential strategic partners and potential investors; helps gather competitive intelligence and even provides inspiration for new products and services. Conference Guru works with conference organizers to pass great deals to gre...
The Internet of Things will challenge the status quo of how IT and development organizations operate. Or will it? Certainly the fog layer of IoT requires special insights about data ontology, security and transactional integrity. But the developmental challenges are the same: People, Process and Platform. In his session at @ThingsExpo, Craig Sproule, CEO of Metavine, demonstrated how to move beyond today's coding paradigm and shared the must-have mindsets for removing complexity from the develop...
In his Opening Keynote at 21st Cloud Expo, John Considine, General Manager of IBM Cloud Infrastructure, led attendees through the exciting evolution of the cloud. He looked at this major disruption from the perspective of technology, business models, and what this means for enterprises of all sizes. John Considine is General Manager of Cloud Infrastructure Services at IBM. In that role he is responsible for leading IBM’s public cloud infrastructure including strategy, development, and offering m...
"Evatronix provides design services to companies that need to integrate the IoT technology in their products but they don't necessarily have the expertise, knowledge and design team to do so," explained Adam Morawiec, VP of Business Development at Evatronix, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
To get the most out of their data, successful companies are not focusing on queries and data lakes, they are actively integrating analytics into their operations with a data-first application development approach. Real-time adjustments to improve revenues, reduce costs, or mitigate risk rely on applications that minimize latency on a variety of data sources. In his session at @BigDataExpo, Jack Norris, Senior Vice President, Data and Applications at MapR Technologies, reviewed best practices to ...
Widespread fragmentation is stalling the growth of the IIoT and making it difficult for partners to work together. The number of software platforms, apps, hardware and connectivity standards is creating paralysis among businesses that are afraid of being locked into a solution. EdgeX Foundry is unifying the community around a common IoT edge framework and an ecosystem of interoperable components.
Large industrial manufacturing organizations are adopting the agile principles of cloud software companies. The industrial manufacturing development process has not scaled over time. Now that design CAD teams are geographically distributed, centralizing their work is key. With large multi-gigabyte projects, outdated tools have stifled industrial team agility, time-to-market milestones, and impacted P&L stakeholders.
"Akvelon is a software development company and we also provide consultancy services to folks who are looking to scale or accelerate their engineering roadmaps," explained Jeremiah Mothersell, Marketing Manager at Akvelon, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"IBM is really all in on blockchain. We take a look at sort of the history of blockchain ledger technologies. It started out with bitcoin, Ethereum, and IBM evaluated these particular blockchain technologies and found they were anonymous and permissionless and that many companies were looking for permissioned blockchain," stated René Bostic, Technical VP of the IBM Cloud Unit in North America, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Conventi...
In his session at 21st Cloud Expo, Carl J. Levine, Senior Technical Evangelist for NS1, will objectively discuss how DNS is used to solve Digital Transformation challenges in large SaaS applications, CDNs, AdTech platforms, and other demanding use cases. Carl J. Levine is the Senior Technical Evangelist for NS1. A veteran of the Internet Infrastructure space, he has over a decade of experience with startups, networking protocols and Internet infrastructure, combined with the unique ability to it...
22nd International Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, and co-located with the 1st DXWorld Expo will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud ...
"Cloud Academy is an enterprise training platform for the cloud, specifically public clouds. We offer guided learning experiences on AWS, Azure, Google Cloud and all the surrounding methodologies and technologies that you need to know and your teams need to know in order to leverage the full benefits of the cloud," explained Alex Brower, VP of Marketing at Cloud Academy, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clar...
Gemini is Yahoo’s native and search advertising platform. To ensure the quality of a complex distributed system that spans multiple products and components and across various desktop websites and mobile app and web experiences – both Yahoo owned and operated and third-party syndication (supply), with complex interaction with more than a billion users and numerous advertisers globally (demand) – it becomes imperative to automate a set of end-to-end tests 24x7 to detect bugs and regression. In th...
"MobiDev is a software development company and we do complex, custom software development for everybody from entrepreneurs to large enterprises," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Coca-Cola’s Google powered digital signage system lays the groundwork for a more valuable connection between Coke and its customers. Digital signs pair software with high-resolution displays so that a message can be changed instantly based on what the operator wants to communicate or sell. In their Day 3 Keynote at 21st Cloud Expo, Greg Chambers, Global Group Director, Digital Innovation, Coca-Cola, and Vidya Nagarajan, a Senior Product Manager at Google, discussed how from store operations and ...
"There's plenty of bandwidth out there but it's never in the right place. So what Cedexis does is uses data to work out the best pathways to get data from the origin to the person who wants to get it," explained Simon Jones, Evangelist and Head of Marketing at Cedexis, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that CrowdReviews.com has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5–7, 2018, at the Javits Center in New York City, NY. CrowdReviews.com is a transparent online platform for determining which products and services are the best based on the opinion of the crowd. The crowd consists of Internet users that have experienced products and services first-hand and have an interest in letting other potential buye...
SYS-CON Events announced today that Telecom Reseller has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. Telecom Reseller reports on Unified Communications, UCaaS, BPaaS for enterprise and SMBs. They report extensively on both customer premises based solutions such as IP-PBX as well as cloud based and hosted platforms.