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<< Part 5 Virtuozzo Overview

1. 1. Microsoft’s Hyper-V
      1. Guest OS’s Supported
      2. Driver’s Support
      3. Speed of Guest OS
      4. Ease of Management
      5. Support
      6. Conclusion

Microsoft’s Hyper-V.

Microsoft is relatively new to the Hypervisor game, but their dominant position in the computing world gives them some distinct advantages over the competition. Two of these advantages are Driver Support and Bundling.

The Core of Hyper-V is available as a free download from the 2nd of October 2008 though the entire interface is text based. You can also buy various versions of Windows Server 2008 that have Hyper-V bundled in. These are not free of course, but have significantly more features mainly in the field of management of Hyper-V.

Guest OS’s Supported.

Microsoft’s Hyper-V architecture, like Xen, requires one guest OS to be the dominant OS. Microsoft calls this the Parent Partition. However unlike Xen, this Parent Partition must be Windows Server 2008.

In addition, Microsoft’s Hyper-V only runs on x64 based processors that have virtualization support. In other words, they must support the Intel-VT or the AMD-V technologies.

The guest OS’s must be enlightened, meaning that they must be aware of the underlying Hyper-V. Currently, Hyper-V supports only Windows Server (Right from Windows Server 2000 with SP4), Windows Vista SP1, Windows XP Professional, and SUSE Linux.

Driver’s Support.

This is a huge plus of using Microsoft Products. Since the Parent Partition has a version of Windows Server 2008 running already, and the guest OS’s are enlightened, it means that whatever guest OS’s are running will be able to leech of the driver support of Windows Server 2008 which will already support most of the hardware available.

The enlightened OS’s will communicate with the Parent Partition via a VMBus, that will facilitate all I/O requests to the hardware.

Speed of Guest OS.

Compared to other Hypervisor solutions like Xen and VMWare, Hyper-V is a bit slower. This is a direct consequence of having a slightly larger code base tying in to Windows Server 2008. However, given the fact that Hyper-V is still very new, and the difficulty of conducting tests in a full blown environment with say 300 Virtual machines, this result is debatable.

In addition, certain License agreements prevent the disclosure of performance parameters on open forums without the consent of the company in question, and this means that objective comparisons need the approval of all the major players. This isn’t likely to happen.

Ease of Management.

If you download the basic Hyper-V from Microsoft’s website, you’re not going to find it easy at all to manage the systems. Microsoft offers products that help you to remotely control the Hypervisors using MMC snap ins that point to the Hypervisor, but it’s still a pain.

However, if you buy Windows Server 2008 with Hyper-V bundled into it, then it’s a whole new ball game. You have a full blown GUI with all the tools you need to manage and control the guest OS’s. In short, as far as Microsoft goes, you get what you pay for.

This is unlike Xen of course where you can easily find high quality free tools.

Support.

If you buy Windows Server 2008, you get the standard support that Microsoft offers you. In addition, you can buy separate support packages tailored for your business, as well as training programs for your employees.

Conclusion.

Which solution you decide to implement will depend not only on your business needs, buy also your mentality. If you’re looking for a cheap powerful hypervisor with great management tools, and you’re also a hands on kind of a person, you should go with Xen.

If your needs are not so specific and varied, and you’re just looking for a quick way to virtualize your hardware, but still need good support and management services, you should go with Virtuozzo.

If you’re a Microsoft fan, then you realize that there are benefits in dealing with Microsoft. For example, all their products work together, and it’s much easier for Microsoft based software to talk to each other. Given this outlook, you would probably go with the Hyper-V.

I hope you enjoyed this discussion on Virtualization, and wish you success in your efforts!

<< Part 4 Xen Overview

1. 1. Virtuozzo.
      1. Guest OS’s Supported. |outline
      2. Driver’s Support. |outline
      3. Speed of Guest OS. |outline
      4. Ease of Management. |outline
      5. Support.
      6. Virtuozzo Summary. |outline

Virtuozzo.

Virtuozzo is a product developed by Parallels Inc., and is an OS virtualization software. This means that it differs from a product like Xen in two important ways:

1. It is proprietary, and therefore closed source and not free.

2. It is more like a Type II Virtualization software (though not quite) as opposed to Xen, which is a Type I.

The technical term to describe Virtuozzo’s technology is Operating System-level virtualization.

Guest OS’s Supported.

This is the biggest limitation of Virtuozzo. It is also it’s biggest strength. Due to it’s very nature as an Operating System-level Virtualization implementation, Virtuozzo runs on top of a standard OS instead of directly on top of the hardware. This means that it can only host guest OS’s that are the same as the OS on which it is running. Let us understand this a bit more.

Virtuozzo isn’t a “true” virtualization software at all. While it does allow various instances of a guest OS to run, in reality, they are other instances of the main OS. That is why you cannot have a Guest OS that is different from the Main OS.

How does this matter? Well, there are several implications, not the least of which is licensing issues. Till just a little while back, Microsoft’s license agreement was such, that if you were running 7 instances of Windows Server on Virtuozzo (Which in turn was running on a main Windows Server OS), you would need to buy just one license, whereas you would have to buy eight licenses if you were running a full virtualization solution like Xen.

Microsoft has since updated it’s licensing agreement, and you can now run upto four instances of a Windows Server with just one license. Still, it’s quite a cost saving over a Hypervisor.

Other implications are that it’s easier to manage. If you have to apply a security update, you just need to install it on the Main OS and not individually on all 7 guest OS’s.

Of course as mentioned earlier, unlike a hypervisor, you are limited to guest OS’s that are the same as that on which Virtuozzo runs. That currently includes Windows Server 2003 and most Linux Distributions.

Driver’s Support.

This isn’t at all an issue with Virtuozzo. If you have drivers for your hardware on the Main OS  (which you probably will) on which Virtuozzo runs, you will have no issues with drivers for your guest OS’s, since they are just instances of the main OS.

Speed of Guest OS.

There’s no doubt that Virtuozzo runs very fast. Much faster than a hypervisor would since there is only one instance of the kernel running. In fact, the overhead for the guest OS is usually just between 1-3%

Ease of Management.

Since Virtuozzo is an Operating System-level virtualization implementation, the management is inherently simpler. In addition, Virtuozzo comes with a suite of management tools that assist the administrator in carrying out all the important task associated with OS virtualization.

Support.

As Virtuozzo is a piece of commercial software, support is extensive. Various plans can be purchased from Parallels Inc. 30 days of installation support is provided with every purchase of Virtuozzo, as well as a software maintenance agreement for the first year. In addition, Virtuozzo provides training courses for your staff for their products.

Overall, if you want to go Enterprise with Virtuozzo, you will be able to get all the back up you need.

Virtuozzo Summary.

For all the benefits of Virtuozzo, the only price that you pay is the lack of flexibility of being able to run whatever OS’s you want. Also, if there is an issue like a kernel crash of the main OS, then the whole system goes down.

However, several users look on the ability to run multiple instances of an OS as an advantage. It makes management simpler, and can reduce licensing costs.

>> Next Part 6 Microsoft’s Hyper V

<< Part 2 - Types of Hypervisor Technology

1. Considerations when choosing a Virtualization Platform.
   1. Various types of Guest OS’s supported.
   2. Drivers Support.
   3. Speed of Guest OS.
   4. Ease of Management.
   5. Support.

Considerations when choosing a Virtualization Platform.

When you set about choosing a Hypervisor, you will need to look at the following parameters to reach a decision.

Various types of Guest OS’s supported.

Each hypervisor can support certain Operating Systems (OS’s). This makes sense, since each OS will work with the hardware under normal circumstances in different ways. The hypervisor needs to be built according to what OS’s are supposed to run on it.

However, other OS’s can work even on Hypervisors not specifically built for them. But predictably, if something goes wrong, you won’t get the answers and support from the Hypervisor support center that you normally will.

In addition, certain OS’s are aware of the hypervisor. These are said to have enlightened I/O. These OS’s run better on Hypervisors since they can interact with the Hypervisor in more efficient ways, essentially telling it - “Don’t worry. I know you exist as well as the problems you’re facing. I will do what’s easiest for you”.

Some OS’s that do not have enlightened I/O can be made to be enlightened with a patch from the company.

Drivers Support.

Since the Hypervisor is going to run directly on the Server Hardware and must then present a consolidated view to the guest OS’s, it must have all the necessary software to be aware of the latest underlying hardware.

Most Hypervisors support a limited set of hardware that will be exposed to the Guest OS’s, and this can be a deal breaker if your particular hardware set isn’t represented properly. Various Hypervisors take different approaches to the problem as will see in the later sections.

Interestingly, Type II Virtualizations will suffer less from this problem as they already take the hardware snapshot from the Main OS.

Speed of Guest OS.

This is a question of efficiency. How fast do guest OS’s run on the given Hypervisor? In the case of Type II Virtualizations, this will be the speed relative to the Main OS.

Ease of Management.

This aspect is already being tagged as the main differentiating factor between hypervisors. There are a plethora of issue to be managed including security, resource allocation, and Guest OS installation.

It also addresses whether or not the Hypervisor has a GUI interface, making it easy for even non-technical persons to set it up.

Another aspect of management unrelated to the above, is a technical issue as to how the Hypervisor manages the various OS’s and keeps them in separated memory spaces. That issue will be covered in in the individual review of the Hypervisors.

Support.

If you’re a business for whom downtime is costly, you will most definitely want to get a product that has commercial support. You can’t afford to play around and test what’s right and what’s not. In these cases, paying extra for professional support is a must.

On the other hand, if you want to give virtualization a whirl in a small test scenario first, you might have a lot of time to find out the details of how it works for yourself. In this case, support becomes secondary and you can focus on features that make more sense to you, like price.

>> Part 4 Xen Overview

<< Part 3 - Considerations while choosing a virtualization Platform

1. 1. Xen.
      1. Guest OS’s Supported. |outline
      2. Driver’s Support. |outline
      3. Speed of Guest OS. |outline
      4. Ease of Mangement. |outline
      5. Support.

Comparisons of Virtualization Software.

Based on the parameters in the article on considerations for choosing a virtualization platform, it’s time to move into a little more detailed explorations of the various Hypervisor based Virtualization Software. We’re going to look at three Hypervisors, namely Xen, Virtuozzo, and Microsoft’s Hyper-V.

Xen.

Xen is an Open Source Virtualization Software. It was originally developed by the University of Cambridge Computer Laboratory and is now released under the GPL license.

Since Xen is open source, it is widely used and has a large support community. Major chip makers like Intel and AMD have contributed to source code for Xen in order to enable it to utilize certain CPU architectures.

Guest OS’s Supported.

Xen requires the Guest Operating Systems to be enlightened. This means that if you want to run certain OS’s using Xen as the Virtualization platform, they have to be modified to make them aware that they are running on a hypervisor and not real hardware. This isn’t usually a problem since more and more OS’s are now offering packages that make them enlightened.

Even open source OS’s like Ubuntu now have packages that enable it to be enlightened. In fact, they have had it for quite some time now.

However, there are restrictions on which versions of Windows can run. All Windows Products after Windows Vista SP1 can be enlightened and even Windows XP SP3 can have this patch applied.

However, Intel and AMD have brought out special CPU’s namely Intel VT and AMD V respectively that allow guest OS’s to run on them unmodified. This means that if the CPU supports any of the above technologies, the guest OS’s need not be enlightened can can be run “as is”.

Driver’s Support.

Xen takes an interesting approach to the Device Driver problem. In order to run Xen, one of the guest OS’s must be special. It means that one guest OS must be Prima Inter Pares, or the First among equals. This special guest OS is called, in Xen terminology, dom0.

Xen puts all the headache of device driver management on the dom0 guest OS. This is a good thing, because most OS’s already have native support of the most common hardware, and the dom0 is no exception. For the record, the dom0 is usually Linux. The dom0 then interfaces with all the other guest OS’s and provides them with the illusion of their device drivers accessing the hardware directly.

If the guest OS’s are enlightened, then the drivers will know that they are not dealing with real hardware and will generate appropriate instructions.

Overall, the driver support for Xen is fairly robust and there are many different solutions depending on the type of guest OS and whether they are enlightened or not.

Speed of Guest OS.

Compared to other Virtualization solutions like VMWare, Xen is noticably faster and can host more Guest OS’s. The speed of a guest OS running on Xen is almost the same as that of Linux running directly on the hardware.

Ease of Management

Xen has a large number of management tools. Since it is open source, several management tools are open source as well including Xen Tools, Ganeti. There are plenty of options here and you can pick and choose.

Support.

Even though Xen is open source, you can still get paid support via Citrix Sytems which distributes an Enterprise Version of Xen for Mission Critical Business. If you don’t want to go for paid support, there is a large community base which will readily answer your questions. Of course, you may not get the specific and speedy help that you’re looking for.

This is a great advantage in using Xen. You can use it either as a test deployment, or as an outright solution. If you go for the latter, you can opt for the paid Enterprise version.

>> Part 5 Virtuozzo Overview

<< Part 1 - Understanding Virtualization

1. Types of Hypervisor Technology.
   1. Type I Hypervisors.
   2. Type II Hypervisors. |outline
   3. Comparison of the two Types of Hypervisors

A Type II approach to Hypervisors

Once more, as in Type I, the three guest OS’s are unaware of the fact that they are running on anything but the hardware directly.

Comparison of the two Types of Hypervisors.

For speed and efficiency, the Type I Hypervisors are definitely better. Since they run directly on the hardware and manage it face to face, they are able to work without cutting through the various layers that hamper the speed of the Type II Hypervisors.

Type II Hypervisors run on client systems where considerations of speed are less important. They can be installed directly on the Operating system and are thus much easier to setup. In addition, Type II Hypervisors support a much broader range of hardware since the hardware resources are provided by the underlying Operating System on which it runs.

Examples of Type I Hypervisors are Microsoft’s Hyper-V and ESX Server. Examples of Type II Hypervisors are VMServer and Microsoft’s Virtual Server

1. Understanding Virtualization.
   1. Two types of Virtualization.
      1. Hardware Partitioning.
      2. Hypervisor Technology.
   2. Benefits of Virtualization.
      1. Reducing Costs of Hardware.
      2. Optimized Adjustment of System Resources.
      3. Easy overview of all IT resources at a glance.

Understanding Virtualization.

Virtualization is a concept that allows the abstraction of Hardware from the users or the Operation system. In simple terms it means allowing several operating systems to run on a single computer without the operating systems being aware of the fact.

Conversely, virtualization can also be used to pool dozens of computers and computer hardware together in such a way that they run as a single or multiple units.

Two types of Virtualization.

One can think of virtualization in two ways:

Hardware Partitioning.

This means that you physically dissect the server hardware in and run an operating system on each sector. This has the advantage of physically separating the resources used by various Operating systems.

However, several benefits are lost in this approach, one of which is using overpowered hardware to carry several operating systems. In fact, one might argue that Hardware Partitioning defeats the purpose of Virtualization.

Hypervisor Technology.

Hypervisor technology refers to placing a layer of software between the hardware and the multiple Operating systems (called guest operating systems) (or otherwise as we will see below) that will share the same hardware. The software layer called the hypervisor intercepts the requests from the guest operating systems and handles them in such a way that the operating systems have no idea that they are sharing resources.

Since the Hypervisor technology is one offering most of the benefits of virtualization, we are going to be focusing only on this technology for the rest of the article.

Benefits of Virtualization.

Virtualization offers the following Benefits.

Reducing Costs of Hardware.

Since you can have many users using the same hardware, you save on the cost of buying multiple computers for each person.

Optimized Adjustment of System Resources.

Different users require different resources at various points of time. Without virtualization, some hardware will be strained, and some hardware will be underused at any given point. Virtualization handles this problem by dynamically allocating resources amongst the various operating systems as and when the need arises.

Easy overview of all IT resources at a glance.

When you use virtualization, you find that you are able to take a bird’s eye view of all your IT resources. This is because you are not concerned with their physical location that may be scattered in many different places. Instead you view logical systems that are easy to understand and consolidate.

>> Part 2- Types of Hypervisor Technology