The Pervasive Data Center

At the end of July, Sun posted a screenshot from "Project Renaissance," an effort aimed at creating a new user interface (UI) for OpenOffice. The prototype includes a "ribbon" UI in the vein of the one that Microsoft introduced for Office 2007. Perhaps unsurprisingly, many of the user comments were critical and devolved into Microsoft bashing.

I never got the ribbon-hate myself. Well, OK, that's not really true. A lot of people don't like change and a lot of people like ragging on Microsoft for whatever reason.

However, I always found it more than a bit ironic that a lot of the same people who routinely claim that Microsoft doesn't innovate were, in this case, suggesting this was a good opportunity to get users moved to OpenOffice where they could avoid such a disruptive change.

For my part, I found the ribbon took some getting used to but now I like it for the most part. Like other Microsoft products, I find the design a bit garish but the mechanics generally work well enough for me.

So I don't see anything wrong, at least in principle, with OpenOffice introducing a ribbon interface. There are a lot of broader issues around OpenOffice and its future. These include Oracle's acquisition of Sun, fragmented development by a variety of companies, and the lack of a clear mission at the level of the project as a whole. Part of the problem is that while a free/cheap, "good enough" word processor may be something that a lot of end users want, that's not really a business for anyone. For its part, IBM has used OpenOffice to tie into document-related business processes. But that's about something fundamentally different from OpenOffice, the word processor.

Beyond the question of what OpenOffice wants to be when it grows up, though, there is something specific about the prototype that bothers me.

To understand why, it's important to understand what Microsoft was trying to accomplish by introducing the ribbon. For the full story, I highly recommend this video by Jensen Harris of the Office User Experience Team from MIX08. However, in a nutshell, the ribbon essentially ripped out years of accumulating menu items and other UI elements and replaced them with something designed from the ground up. It was a bold choice but the nature of the problem meant that it didn't lend itself to a piecemeal fix--indeed, piecemeal fixes were what caused the problem in the first place.

The OpenOffice prototype, on the other hand, appears to add a ribbon while leaving the menu system extant. This way lays user interface madness even if it does provide more choices. Good design is often (indeed is usually) about constraining choice rather than expanding it.

(For a different perspective, see the CNET piece by Dong Ngo.)

[Update: Additional commentary from Stephen Hemminger added.]

Microsoft set off a barrage of commentary earlier this week when it released three drivers under the GPL v2 to be part of Linux. The main purpose for doing so appeared to have been to make Windows Server and Hyper-V more effective as a virtualization foundation for Linux guest operating systems.

I was less shocked by the news than some. It struck me as a smart business move by Microsoft to further dispel both the reality and appearance of not playing well with other operating systems and tools. From a practical perspective, offering technology to Linux that lets it work better with Windows pretty much had to be done in the form of open-source code. At the same time, the Microsoft of today is far more accepting of the fact that like it or not, Linux is going to be a fixture at many of its customers and they're going to have to live with that.

Thus, releasing these drivers seemed to make a lot of sense and, while it was clearly a big step on the part of Microsoft, it certainly wasn't inconsistent with the company's recent posture toward open source, especially since Sam Ramji came onboard to be senior director of platform strategy.

However, it now turns out there's another layer to the story.

On Monday, Stephen Hemminger made a posting to his blog, Network Plumber's Journal. Stephen is a principal engineer with Vyatta, an open-source networking infrastructure vendor. Prior to Vyatta, he was with the Open Source Development Labs (and then the Linux Foundation) and was one of the largest contributors of Linux kernel code (PDF).

This saga started when one of the users on the Vyatta forum inquired about supporting Hyper-V network driver in the Vyatta kernel. A little googling found the necessary drivers, but on closer examination there was a problem. The driver had both open-source components which were under GPL, and statically linked to several binary parts.

The GPL does not permit mixing of closed- and open-source parts, so this was an obvious violation of the license. Rather than creating noise, my goal was to resolve the problem, so I turned to Greg Kroah-Hartman. Since Novell has a (too) close association with Microsoft, my expectation was that Greg could prod the right people to get the issue resolved.

It took longer than expected, but finally Microsoft decided to do the right thing and release the drivers.

By way of brief background, the GPL under which Linux is licensed considers static linking--the combination of software components by a developer--to create a "derivative work" of those components. There are a lot of complexities, nuances, and ambiguities, but for our purposes here, the bottom line is that if you statically link GPL libraries or other GPL'd code into your program, the entire program has to be released under the GPL.

Which Microsoft had not done.

I had a conversation with Stephen Hemminger, who initially reported the potential issue with Microsoft's driver, and he provided me with some additional technical specifics. According to Stephen, the issue revolves around a feature of the Linux kernel called EXPORT_SYMBOL_GPL that allows for interfaces to be marked as only available to modules with a GPL-compatible license. From Stephen's perspective, Microsoft's proprietary code had to use some of these interfaces that "the kernel did not want to offer to non-GPL [code]."

If that all seemed a bit geeky technical, well it is. Very possibly a violation of the GPL but hardly one that is simply flagrantly flouting the law. And, from Hemminger's perspective, "once Microsoft was aware of it, they were eager to resolve." He said that he first discovered this in March, so four months is actually fairly rapid resolution as such things go in large companies.

Greg Kroah-Hartman, who is a fellow at Novell and was very involved in the open-sourcing of the Hyper-V drivers, certainly seems to believe the licensing problem played a role in Microsoft's decision. In an e-mail exchange with ZDNet's Mary-Jo Foley, he writes:

MJF [Mary-Jo Foley]: Hemminger is claiming Microsoft put the LIC code under the GPL because it was in violation of the GPL. Is this true? Did you have to suggest to (Microsoft Platform Strategy Chief Sam) Ramji & Co. that they were in violation in order to get them to agree to release the code under GPLv2?

GKH [Greg Kroah-Hartman]: I didn't have to "suggest" anything, I only had to merely point out the obviousness of the situation  :)

MJF: If this isn't accurate, could you let me know how to interpret (Hemminger's) comments on his blog.

GKH: No, that sounds accurate.

Microsoft itself hasn't commented on the matter.

Based on what we know at this point, I draw a couple of conclusions. The first is that if Microsoft were the Microsoft of five years ago, it would have found some way to mitigate the problem that did not involve releasing code for Linux under the GPL.

At some level, it is now philosophically attuned to working with Linux in a way that it wasn't when one of Sam Ramji's predecessors, Martin Taylor, could be described as "Microsoft's Top Anti-Linux General."

But that said, it seems more than likely that their little license problem provided, at the very least, a forcing function to make their GPL contribution happen.

We've been hearing a lot about thinner client devices of late. Netbooks are a hot topic, whether or not they're really a distinct category of device. I've wondered if there might not be a role for a sort of ebook-on-steroids. And Google's Chrome OS, pitched for a browser-centric world, had the digerati all in a flutter a few weeks back.

A lot of this activity reflects a general move away from software that is locally installed and run on a traditional PC to software and services housed on servers out on the network--in the cloud, to use the lingo du jour. It's enabled in no small part by increasingly pervasive networks including wireless ones of various kinds.

However, although cloud computing tracks improvements in networks, it doesn't necessarily sync up so cleanly with the parallel improvements going on in computers themselves. As a commenter put it in a recent post of mine: "The thing that I don't understand about the move to "cloud-based services" is that it seems at odds with Moore's Law. Specifically, devices are going to have more & more processing power, disk space & memory - why would you want to offload processing to the cloud?"

This is a deceptively deep comment and one that touches a lot of basic architectural questions about how we will run software and where we will run it.

One thought is that we're not really running counter to Moore's Law. Rather, we're moving the increased number of transistors that Moore's Law gives us from the client to the server. We're making clients thinner (and therefore more portable, cooler, and so forth) and the servers fatter.

There's some truth in that with mobile phones perhaps offering the clearest illustration.

But, for more notebook-like clients there's a lot of processor and graphics horsepower on the local computer that's going to waste much of the time. And, in any case, telecommunications infrastructure places hard limits on bandwidth for a given time of place, but we can dial up and down our local compute horsepower by selecting devices with different characteristics. So it makes more sense to favor local processing much of the time.

In fact, the fundamental thing that thinner clients and cloud computing tackle isn't really the movement of computing off the client but rather the movement of "state" off the client--which is to say data, applications, and customizations specific to a given user.

As a practical matter, most clients still store some amount of state. In the days of  old, terminals didn't store anything locally. Sun's Sun Ray line comes closest to replicating this experience in modern thin clients. However, even browsers store cookies and can be configured with extensions and plug-ins that will vary from one installation to the next.

And, for most purposes, this is probably a reasonable enough state of affairs. Our personal devices are personal anyway; we just want to get away from having to load and manage custom software for each individual task that we want to do. Shared, public clients are a different matter, of course. However, in this case, a lowest-common-denominator software load (such as a browser) is typically sufficient.

There is clearly a lot  of work left to do and battles, both technical and political, left to fight to arrive at the best architectural models and programming practices for this new generation of client-server computing. For example, do "rich Internet applications" live in the browser a la Microsoft's Silverlight or is a separate framework such as  Adobe's AIR a better approach? Where do .NET and Java fit in?

These (and many others) are not small questions. Application writers need to understand at a very granular level the environment for which they're writing. And there is very much a tension between richness of the client experience and the degree to which we can standardize and simplify that client.

Microsoft's Server and Tools Business did the virtual conference thing for industry analysts last week. Fellow analyst Judith Hurwitz ably describes the limitations of this format. I concur with much of what she writes.

That said, I give Microsoft props for trying. A lot of companies have canceled or decided not to hold in-person events this year without making any real effort to put together an alternative. Limited interactivity and engagement aside, some of the pre-recorded videos were informative, STB President Bob Muglia was in typical energetic form, and I had good telephone discussions on a variety of topics.

Here are some of my take-aways and observations.

"Costs less" was a big part of Microsoft's pitch. This is consistent with the theme of its consumer advertising. It's also consistent in that Microsoft chooses targets for comparison with some care. For example, Microsoft isn't so much emphasizing low cost in the context of general scale-out infrastructure (where Linux and other open-source software is most widely deployed and popular today). Rather, Bob Muglia emphasized being able to put together solutions with partners at a fraction of the cost of proprietary software; he especially emphasized business intelligence, which has been the focus of a great deal of SQL Server development over the past few years.

Hyper-V. Muglia said that the "first year of Hyper-V being out has been significantly better than I expected." He also noted that it has been "gaining share every day." Of course, Microsoft would have to gain a lot of share to seriously dent VMware's dominance. That said, Microsoft's virtualization solutions (together with those of competitor/partner Citrix) will often be the low-effort path for Microsoft shops. Hyper-V gets a big boost this fall when it gets Live Migration as part of the Windows Server 2008 R2 release. This is Microsoft's counterpart to VMware's VMotion (which allows running VMs to be moved to another physical server without interruption). Even Microsoft will now pretty much admit that this technology is table stakes for a serious virtualization deployment.

Cloud computing was, of course, much discussed in the course of the day. There are a number of aspects to this but I'll focus here on Azure, which I discussed with Steven Martin, the senior director of developer platform product management. Microsoft describes the Azure Services Platform, to use its full name, as a "cloud operating system" that provides a set of services such as SQL database access. A few points from our conversation:

• I hear a lot of concerns about security and privacy in off-premise cloud deployments. Martin notes that payroll was one of the first widely outsourced enterprise applications and Salesforce.com customer relationship management is the poster child for software as a service. Your employee and your customer data--few things are more confidential. This is a great point. It's not that we shouldn't be concerned about cloud security but the reality is that we've been letting third parties access much of our data for years.
• What additional types of services might we see for Azure? Martin highlighted commerce services such as a shopping cart and B2C (business-to-consumer) as something "we talk a lot about." Reporting and compliance was another area he mentioned. "Potentially" but more in the vein of "if customers demand them" is database models other than the existing SQL Data Services. In general, Microsoft sees Azure as bridging internal .NET development and an external cloud so they're probably hesitant to head in directions that don't fit as well with an internally hosted environment.
• One final interesting angle is the intersection between an abstracted cloud computing platform like Azure and multi-core/parallel programming. As I've previously written in a different context, it seems that one of the ways that we'll make it possible for application programmers to deal with the inherent difficulty of writing parallelized code is to provide them with abstractions that handle a lot of the low-level rocket science. Azure and other systems in a similar vein could well turn out to be appropriate abstractions for this purpose.

Those are just the highlights. Other topics we covered included client virtualization (Microsoft seemed more open to possibilities than in the past), Silverlight ("barely nine months in... and will continue to see a gloves off nasty fight with Adobe"), and Microsoft's continued focus on management as its big differentiator around virtualization in general.

What strikes me most about the admittedly somewhat selective set of  things that I have highlighted is that it's generally forward-looking. Yes, Windows Server is still at the core of much that STB does, but there's also substantial focus on virtualization, cloud computing, and Web-centric approaches in general. That's a substantial change from a few years ago.

LAS VEGAS--The Day One keynotes at Citrix Synergy 2009 were about users and desktops. Today was nominally about data centers and clouds--of which there were a variety of announcements. However, Citrix's XenClient ("Project Independence") loomed large as well.

Of the products discussed on stage, XenClient is perhaps furthest from being a fully realized product. But is also offers an intriguing window into how the PC as we know it is likely to fundamentally change over the coming years.

XenClient is a "Type 1" native hypervisor that sits on a PC and hosts one or more guest operating systems. This approach contrasts with the "Type 2" hosted hypervisors that are far more common on PCs today.

There are good reasons why we tend to see native hypervisors on servers and hosted hypervisors on desktops. Native hypervisors are higher performance, especially when it comes to interacting with networks and disks. As a result, it wasn't until native hypervisors like VMware ESX Server and Xen came to market that x86 virtualization started to seriously move beyond useful but relatively narrow uses such as in test and development labs.

The downside of native hypervisors is that, because they sit directly on top of a system's hardware, they have to take over a variety of the functions that an operating system usually performs. For example, a native hypervisor has to deal with things like power management and needs to know how to talk to graphics cards and chips, network and storage adapters, and other system hardware.

(Depending upon the virtualization architecture in question, some device interactions can be passed through to the guest operating systems, but the point remains that a native hypervisor is exposed to hardware details and idiosyncrasies that are masked if the hypervisor is hosted on an operating system.)

The great diversity of client hardware relative to server hardware therefore makes running native hypervisors on a PC tricky business.

It's also been the case that vendors haven't exactly pushed client-side virtualization--in contrast to using application virtualization to deliver software to clients--in a broad way. Hosted virtualization products handle specific use cases such as security (VMware ACE), running Windows applications on Macs (Parallels Desktop for Mac, VMware Fusion), and software development (VirtualBox, VMware Workstation). Start-ups are also tackling the security angle with alternative approaches. RingCube uses containers. Neocleus uses a Xen-based native hypervisor.

But no large vendor has seriously pushed a broad-based Type 1 hypervisor for the client. Microsoft, for its part, has been publicly skeptical about the idea. (Not especially surprising given that Microsoft has only reluctantly embraced virtualization--in part because native virtualization takes over some of the traditional tasks of the operating system.)

That changes with XenClient, a project that Citrix has collaborated on closely with Intel.

Here's how Citrix describes XenClient and its vision for desktop computing:

XenClient is a strategic product initiative with partners like Intel, focused on local virtual desktops. We are working together to deliver on our combined vision for the future of desktop computing.

This new virtualization solution will extend the benefits of hosted desktop virtualization to millions of mobile workers with the introduction of a new client-side bare metal hypervisor that runs directly on each end user's laptop or PC. This together with an innovative back-end desktop management solution for creating, delivering, and updating corporate desktop computing environments will transform the way corporate desktops are delivered and managed, giving IT all the security, simplicity and cost savings of centralized management, with an unprecedented level of performance, personalization and freedom for end users.

To net it out, Citrix is pushing for a future in which a hypervisor is a standard abstraction layer for every cleint and server--just the way that x86 architectures of all stripes are architected and built. Think of it as a BIOS on steroids if you will.

Citrix's interest here is obvious. After all, its strategy is to make money from managing virtualized environments. Thus, continuing with a theme from Synergy's first day, XenClient--like XenServer--will be free when made available later this year.

Intel's interest here is that XenClient is specifically targeted for systems with vPro technology. vPro includes:

• Intel Virtualization Technology (VT)--hardware assists for improved virtualization performance
• Intel Trusted Execution Technology (TXT)--formerly called LaGrande, provides hardware-based rooted security
• Intel Active Management Technology (AMT)--hardware management technology

Intel's Pat Gelsinger said in his keynote that vPro is ramping quickly--he claimed it was in 60 percent of the Fortune 100--but Intel is doubtless actively seeking more reasons to get businesses to upgrade to their latest and greatest client platforms.

The vision here seems a sound one. After all, IT vendors have essentially been adding layers of abstraction to mask complexity since the beginning. Even an operating system is an example of abstraction (actually many of them rolled into one software package). And use cases involving personal PCs used to access corporate networks or protected VMs that run security scanners seem far less esoteric than they did even just a couple of years back.

The question is more one of time frame. When do compelling uses get made available by software vendors in largely transparent ways for end users who are not developers or otherwise ready, willing, and able to explicitly manipulate multiple virtual machines on a single client? It isn't this year but there's a lot of reason to believe that this is the direction the client is headed.

I've been critical of past Microsoft advertising.

The low point may have been calling customers and potential customers dinosaurs for not upgrading to Office 2003.

But Microsoft advertising, in general, has been at best inconsistent, in that it has often spoken to the needs and desires of Microsoft--as opposed to the needs and desires of its customers. (In all fairness, this is hardly a problem unique to Microsoft's advertising or, indeed, to the advertising that comes out of the the tech industry overall.)

But the company's latest, from the Crispin Porter + Boguksy agency, nails it.

As Philip Elmer-DeWitt summarizes:

Her name is "Lauren," and she's making the Apple (AAPL) guys nuts...She's the young, hip, Volkswagen-driving redhead who stars in the latest Microsoft (MSFT) TV campaign. Told that if she can find a 17-inch laptop for under $1,000, she can keep it, Lauren ends up--to the Mac aficionados' dismay--with an HP (HPQ) running Windows Vista.

The message? Sure, Macs are fine. But who can afford one in these times?

The Apple fan club is up in arms. A lot of the reaction is pretty silly and dwells on the fact that the star of the spot is actually an actress and that the events shown are staged. Shocking and surprising, I know.

As for whether the comparison of the 17-inch Apple and HP laptop is completely fair and apples-to-apples? Well, of course it isn't. We're talking advertising here. There has to be a degree of credibility, yes, but absolute objectivity? Hardly.

Best line: the sighingly delivered, "I'm just not cool enough to be a Mac person."

From an advertising perspective, the commercial does have a weakness. It essentially sets the Mac up as the aspirational brand, the laptop that would apparently be Lauren's first choice, if it weren't for its cost. This ad wouldn't fit especially well with a more free-wheeling era.

But this is not that era. And a value message strikes me as a good one for Microsoft in this context, especially as delivered in a light, humorous, and gently hipster-mocking way.

LAS VEGAS--Just like its predecessor a year ago, Silverlight 3 is clearly one of the stars of the Microsoft Mix conference under way here this week.

Silverlight is a Web browser plug-in for Microsoft's Internet Explorer Web browser. (Silverlight also supports Firefox and Safari browsers and Mac OS X in addition to Microsoft Windows. A primarily Novell-developed plug-in, Moonlight, runs on Linux.) Its initial iteration was narrowly focused on media. However, Silverlight's direction is toward enabling a broad class of "rich Internet applications."

So, for example, Silverlight 3 will allow developers to create lightweight Web application experiences that exist outside the browser and offline. Although it retains a strong focus on media, Silverlight is thus starting to look more like a full-fledged rich Internet application.

I'll discuss Silverlight generally in more detail in a future post. More immediately, I want to focus on one demo that I found to be particularly compelling because it addressed a problem that no one has yet cracked in the Web space yet.

The demo, given by David Anthony of Bondi Digital Publishing and Scott Stanfield of Vertigo, came during Wednesday's keynote speech (see video). Bondi has been working with various publishers to put the back issues of magazines online. Vertigo designs and codes software for Microsoft environments; it has been particularly emphasizing visually rich applications built with Silverlight.

Last year, Vertigo's Hard Rock Cafe memorabilia project was a big hit. It used Silverlight's Deep Zoom feature to allow users to dive into and around a digital display of photos, clothing, art, letters, and so forth connected to a variety of rock musicians. Give it a try; it's easier to experience than to explain.

This year's demo also featured Deep Zoom--combined with Silverlight 3's support for deep linking. That is, bookmarking a page within a rich Internet application. (Technically, deep linking is a server-side feature associated with .Net that Silverlight 3 simply exploits.) This demo may not have had quite the "ooh" factor of the Hard Rock one, but I think that it suggests more interesting and more generally useful possibilities.

This year, the project was putting back issues of Rolling Stone magazine online. The basic concept was to show an "entire issue as though pages had the staples torn out of them" with the addition of search and bookmarking features. Thus, you could "flip" through an issue, and dive in to look at detail, if something caught your eye. It's essentially an attempt to replicate the "zero boot time and random access" of a paper magazine as closely as possible.

That's all very nice, though I have to wonder what sort of business model there is around viewing back issues of magazines.

But this--or something like it--could have enormous potential for things like catalogs.

Think about it. What's the nice thing about the user experience associated with a paper catalog? Well, one big thing is that you can flip through it and dive in for a closer look, if a photo or a description catches your eye. Essentially, catalogs are great for browsing.

Contrast this with the typical online catalog. They're great for searching. If you know more or less what you want, search can quickly filter out the almost infinite things that you're not looking for. But casual paging, seeking serendipity? Not so good.

To give just one personal example, I like to flip through the many catalogs that Sierra Trading Post sends to my home, advertising the various overstocks and otherwise heavily discounted products that it sells. I find trying to do the same on Sierra's Web site a poor substitute, unless I'm actively seeking something in particular.

The sort of experience I saw on the stage with Deep Zoom would seem to combine some of the best of the browsing and searching experience. It improves on aspects of a paper catalog; it has search, and the amount of low-level detail isn't constrained by the limits of the printed page. At the same time, it brings browse ability of the digital domain.

It's sometimes a mistake to attempt to mirror the physical world in our computer software. But the way we interact with physical objects is often more than just ingrained. It can just plain work well too. And if we can augment that physical experience in the process of translation, all the better.

[UPDATE 3/19/09: Clarified Silverlight platflorm support.]

I noted last month that embedding the code for server virtualization directly into the hardware, something called an embedded hypervisor, hasn't taken off to any significant degree.

Rather, most IT shops continue to purchase virtualization as a third-party add-on (typically from VMware or Citrix), or they acquire it as part of Linux distribution or Microsoft Windows.

Many of the management and other services associated with virtualization are going to be added on, in any case. However, the thinking of a lot of people went, wouldn't it make sense to at least get the foundation in place as part of the server purchase, given that we're seeing more and more interoperability between the various hypervisors and the software that exploits them?

Since writing that piece, I've received a variety of interesting comments, and had some discussions with IT vendors and others I thought worth sharing.

Reader rcadona 2k commented:

Adopting a hypervisor is an active choice or, in most cases, a surrender of your hardware. Embedded hypervisors aren't just a BIOS; they require formatting your storage a particular way (VMware VMFS, Hyper-V NTFS, LVM/raw LUNs for Xen). The virtual BIOS features amongst hypervisors for the guests are not standardized, and the virtualized guest devices are not standardized. When you pick a Type-1 hypervisor, you lock yourself into another "platform."

Some good points here. We have a a bad habit in the IT industry of using the word "commodity" when we really mean things along the lines of "widely used with variants available from multiple sources" (and, therefore, relatively low-price). Hypervisors are an example of this. They all do roughly the same thing. There are a variety of suppliers. And the price for base-level hypervisors has been sliding toward zero.

But they're not commodities. For all the interoperability work that has been taking place at the management and services layer, there remain significant product differences that affect things as substantial as an IT shop's storage architecture. Some of these will go away--or at least be abstracted away--over time, but not all necessarily will.

Given that the choice of hypervisor still matters in such important ways, it's understandable that people continue to buy them primarily as an explicit component of the broader virtualization software ecosystem that depends on them.

Another feedback theme was just that we're still in the early days of virtualization. Perhaps most notably, when VMware rearchitected ESX Server to create the embedded ESXi version, not all the capabilities and features carried over. (Without going into all the details, the full ESX uses a Linux-based service console to manage the hypervisor; ESXi does away with this and is much thinner as a result. However, the current iteration of ESXi doesn't fully replicate all the capabilities provided by that console.)

However, the VMware partners that I've spoken with fully expect that upcoming ESXi versions will soon reach parity with the older ESX architecture and that this will therefore cease to be a reason to shy away from the embedded approach.

I remain skeptical that embedded, just-built-in hypervisors are going to become the norm that it once seemed they would be. If nothing else, Microsoft's Hyper-V--most likely predominantly installed as part of Windows--will tend to hold sway in Microsoft-centric environments, of which there are many.

At the same time, it's too early to write off the idea of embedding hypervisors just because the idea hasn't gained a lot of initial momentum.

Here's the basic question: where does the hypervisor--the software layer that underpins server virtualization--live and who owns it? Is it just part of the server or is it just part of the operating system?

For now, to be sure, it's often something that IT shops purchase from a third-party--we're mostly talking from VMware here. However, pretty much everyone expects that over time this foundational component will be increasingly built-in--even if the higher-level value-add management and virtualization services that make use of it are explicitly purchased from a variety of sources.

Virtualization vendors have often considered this an important question.

A few years back, I had written a piece about how Novell and Red Hat were adding the Xen hypervisor to their Linux distributions. And that Microsoft had made clear its intention to add virtualization to Windows--technology now known as Hyper-V. In short, virtualization was starting to move into the operating systems of a number of vendors.

Well, that notion didn't sit well with Diane Greene--then CEO of VMware--as she made clear to me by coming over and grabbing me by the lapels(only somewhat figuratively) at an Intel Developers Forum event. From Diane's, admittedly biased, perspective the hypervisor should be independent of any single operating system. I hadn't said otherwise. But I apparently didn't make the opposing case enthusiastically enough.

At the time, VMware ESX Server (its native hypervisor) had to be installed as with any other third-party software product. However, over time, VMware and other virtualization vendors came out with versions of their products that could be installed from a USB memory stick or other form of flash memory. It was called ESXi in VMware's case.

Thus the embedded, or at least embeddable, hypervisor was born with rumors throughout 2007 becoming product announcements in September of that year.

There's actually a lot to be said for the embedded hypervisor. Lots of IT environments--especially enterprise ones--do indeed have a mix of operating systems and operating system versions. Given that, there is indeed a lot to be said for the idea that hypervisors just come with the server as a sort of superset to the firmaware, like BIOS, already loaded on every system. Then IT administrators could just configure any guest OSs they want on top.

It's logical. But it's not really playing out that way--at least so far.

After all the initial excitement in late 2007, embedded hypervisors didn't really go anywhere in 2008. Instead, Microsoft's Hyper-V rolled out and KVM found its way into the main Linux kernel as an alternative style of Linux virtualization backed by Red Hat.

Whether or not it makes "sense," in some theoretical, architectural sense, it's no longer clear to me that embedded hypervisors are going to be the path that the industry predominantly follows.

Rather, at the moment, homogeneous environments are tending towards whatever is built into the OS. And enterprises are going to their ISV of choice--sometimes Citrix for XenServer--but far more often VMware for ESX.

At the very least, it now looks as if--for the foreseeable future--IT shops will acquire virtualization, including hypervisors, in a variety of ways that vary as a function of their individual requirements, circumstances, and vendor alignments.