Server virtualization currently is a trending topic in the IT world. Its popularity and adoption keeps growing, especially in enterprise environments.
What makes virtualization possible are hypervisors.
Mac OS X was the tenth version of the Mac series of operating systems which has many updated features as compared to its previous ones. Similarly, Max OS X has many updated versions and Apple has. Examples of Network Operating System are: Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX, Linux, Mac OS X, Novell NetWare, and BSD, etc. Real-Time Operating System – These types of OSs serve real-time systems. The time interval required to process and respond to inputs is very small. This time interval is called. Generally, we use the term particle for three major sizes; macroscopic, microscopic and subatomic particles. Macroscopic particles are larger than atoms and molecules and are visible to the naked eye. Examples include powder and dust particles. Microscopic particles are invisible to the naked eye but visible through microscopes.
Make some space: If you want to carve your Mac up so that you can run two versions of the OS you will need space. So before you start get deleting. So before you start get deleting.
Server virtualization allows different operating systems running separate applications on one server while still using the same physical resources. These virtual machines make it possible for a system and network administrators to have a dedicated machine for every service they need to run.
Not only does this reduce the number of physical servers required, but it also saves time when trying to pinpoint issues.
In this article, we will discuss what hypervisors are, how they work, and the different types that exist.
A hypervisor is a crucial piece of software that makes virtualization possible. It abstracts guest machines and the operating system they run on, from the actual hardware.
Hypervisors create a virtualization layer that separates CPU / Processors, RAM and other physical resources from the virtual machines you create.
The machine we install a hypervisor on is called a host machine, versus guest virtual machines that run on top of them.
Hypervisors emulate available resources so that guest machines can use them. No matter what operating system you boot up with a virtual machine, it will think that actual physical hardware is at its disposal.
From a VM’s standpoint, there is no difference between the physical and virtualized environment. Guest machines do not know that the hypervisor created them in a virtual environment. Or that they are sharing available computing power. VMs run simultaneously with the hardware that powers them, and so they are entirely dependent on its stable operation.
A bare-metal hypervisor (Type 1) is a layer of software we install directly on top of a physical server and its underlying hardware.
There is no software or any operating system in between, hence the name bare-metal hypervisor. A Type 1 hypervisor is proven in providing excellent performance and stability since it does not run inside Windows or any other operating system.
Type 1 hypervisors are an OS themselves, a very basic one on top of which you can run virtual machines. The physical machine the hypervisor is running on serves virtualization purposes only. You cannot use it for anything else.
Type 1 hypervisors are mainly found in enterprise environments.
Given that type 1 hypervisors are relatively simple, they do not offer many functionalities.
Once you boot up a physical server with a bare-metal hypervisor installed, it displays a command prompt-like screen. If you connect a monitor to the server, what you get to see are some of the hardware and network details. This consists of the CPU type, the amount of memory, the IP address and the MAC address.
Below is an example of a VMware type 1 hypervisor’s screen after the server boots up.
Another type 1 hypervisor may look quite different but they also only allow for simple server configuration. This consists of changing the date and time, IP address, password, etc. In order to create virtual instances, you need a management console set up on another machine. Using the console, you can connect to the hypervisor on the server, and manage your virtual environment.
A management console can be web-based or a separate software package you install on the machine for which you want remote management. Depending on what functionalities you need, the license cost for management consoles varies substantially.
One action you can perform includes moving virtual machines between physical servers, manually or automatically. This move is based on resource needs of a VM at a given moment and happens without any impact to the end-users. It’s the same process if a piece of hardware or a whole server fails. Properly configured management software moves virtual machines to a working server as soon as an issue arises. The detection and restoration procedure takes place automatically and seamlessly.
One of the best features of type 1 hypervisors is that they allow for over-allocation of physical resources.
With type 1 hypervisors, you can assign more resources to your virtual machines than you have available. For example, if you have 128GB of RAM on your server and eight virtual machines, you can assign 24GB of RAM to each of them. This totals to 192GB of RAM, but VMs themselves will not actually consume all 24GB from the physical server. The VMs think they have 24GB when in reality they only use the amount of RAM they need to perform particular tasks.
The hypervisor allocates only the amount of necessary resources for an instance to be fully functional. This is one of the reasons all modern enterprise data centers, such as phoenixNAP, use type 1 hypervisors.
There are many different hypervisor vendors available. Most provide trial periods to test out their services before you buy them.
The licensing costs can be high if you want all the bells and whistles they have on offer.
These are the most common type 1 hypervisors:
VMware vSphere with ESX/ESXi
VMware is an industry-leading vendor of virtualization technology, and many large data centers run on their products. It may not be the most cost-effective solution for smaller IT environments. If you do not need all the advanced features VMware vSphere offers, there is a free version of this hypervisor and multiple commercial editions.
KVM (Kernel-Based Virtual Machine)
KVM is built into Linux as an added functionality. It lets you convert the Linux kernel into a hypervisor. It is sometimes confused with a type 2 hypervisor (see definition below). It has direct access to hardware along with virtual machines it hosts. KVM is an open-source hypervisor that contains all the features of Linux with the addition of many other functionalities. This makes it one of the top choices for enterprise environments. Some of the highlights include live migration, scheduling and resource control, alongside higher prioritization.
To learn more about working with KVM, visit our tutorials How To Install KVM On Ubuntu and How To Install KVM On CentOS.
Microsoft Hyper-V
Despite VMware’s hypervisor being higher on the ladder with its numerous advanced features, Microsoft’s Hyper-V has become a worthy opponent. Microsoft also offers a free edition of their hypervisor, but if you want a GUI and additional functionalities, you will have to go for one of the commercial versions. Hyper-V may not offer as many features as VMware vSphere package, but you still get live migration, replication of virtual machines, dynamic memory and many other features.
Oracle VM
This hypervisor has open-source Xen at its core and is free. Advanced features are only available in paid versions. Even though Oracle VM is essentially a stable product, it is not as robust as vSphere, KVM or Hyper-V.
Citrix Hypervisor (formerly known as Xen Server)
This Server virtualization platform by Citrix is best suited for enterprise environments. It can handle all types of workloads and provides features for the most demanding tasks. Citrix is proud of its proprietary features, such as Intel and NVIDIA enhanced virtualized graphics and workload security with Direct Inspect APIs.
This type of hypervisor runs inside of an operating system of a physical host machine.
This is why we call type 2 hypervisors – hosted hypervisors. As opposed to type 1 hypervisors that run directly on the hardware, hosted hypervisors have one software layer underneath. In this case we have:
Type 2 hypervisors are typically found in environments with a small number of servers.
What makes them convenient is that you do not need a management console on another machine to set up and manage virtual machines. You can do all of this on the server where you install the hypervisor. They are not any different from the other applications you have in your operating system.
When you launch a virtual machine, you get another window to perform all tasks.
Hosted hypervisors essentially also act as management consoles for virtual machines, you can perform any task using the built-in functionalities.
There is no need to install separate software on another machine to create and maintain your virtual environment. You simply install and run a type 2 hypervisor as you would any other application within your OS. With it, you can create snapshots or clone your virtual machines, import or export appliances, etc.
Here is one example of a type 2 hypervisor interface (VirtualBox by Oracle):
You do need to be careful when allocating actual resources with this type of hypervisor.
Bare-metal hypervisors can dynamically allocate available resources depending on the current needs of a particular VM. A type 2 hypervisor occupies whatever you allocate to a virtual machine.
When you assign 8GB of RAM to a VM, that amount will be taken up even if the VM is using only a fraction of it. If the host machine has 32GB of RAM and you create three VMs with 8GB each, you are left with 8GB of RAM to keep the physical machine running. Creating another VM with 8GB of ram would bring down your system. This is critical to keep in mind, so as to avoid over-allocating resources and crashing the host machine.
Type 2 hypervisors are convenient for testing new software and research projects.
It is possible to use one physical machine to run multiple instances with different operating systems to test how an application behaves in each environment or to create a specific network environment. You only need to make sure that there are enough physical resources to keep both the host and the virtual machines running.
As is the case with bare-metal hypervisors, you can choose between numerous vendors and products. Conveniently, many type 2 hypervisors are free in their basic versions and provide sufficient functionalities.
Some even provide advanced features and performance boosts when you install add-on packages, free of charge. We will mention a few of the most used hosted hypervisors:
Oracle VM VirtualBox
A free but stable product with enough features for personal use and most use cases for smaller businesses. VirtualBox is not resource demanding, and it has proven to be a good solution for both desktop and server virtualization. It provides support for guest multiprocessing with up to 32 vCPUs per virtual machine, PXE Network boot, snapshot trees, and much more.
VMware Workstation Pro/VMware Fusion
VMware Workstation Pro is a type 2 hypervisor for Windows OS. It is full of advanced features and has seamless integration with vSphere. This allows you to move your apps between desktop and cloud environments.
It does come with a price tag, as there is no free version. If you want to take a glimpse into VMware hosted hypervisors free of charge, you can try VMware Workstation Player. This is the basic version of the hypervisor suitable for small sandbox environments.
For MacOS users, VMware has developed Fusion that is similar to their Workstation product. It comes with somewhat fewer features, but also carries a smaller price tag.
Windows Virtual PC
It only supports Windows 7 as a host machine and Windows OS on guest machines. This includes multiple versions of Windows 7 and Vista, as well as XP SP3. Virtual PC is completely free.
Parallels Desktop
A competitor to VMware Fusion. It is primarily intended for MacOS users and offers plenty of features depending on the version you purchase. Some of the features are network conditioning, integration with Chef/Ohai/Docker/Vagrant, support for up to 128GB per VM, etc.
Choosing the right type of hypervisor strictly depends on your individual needs.
The first thing you need to keep in mind is the size of the virtual environment you intend to run.
For personal use and smaller deployments, you can go for one of the type 2 hypervisors. If budget is not an issue, VMware will provide every feature you need. Otherwise, Oracle VM VirtualBox is a hypervisor that will provide most of the functionalities generally needed.
Enterprise Environments
Even though type 1 hypervisors are the way to go, you do need to take into consideration many factors before making a decision.
The critical factor is usually the licensing cost. This is where you need to pay extra attention since licensing may be per server, per CPU or sometimes even per core. In the current market, there is a battle going on between VMware vSphere and Microsoft Hyper-V. While Hyper-V was falling behind a few years ago, it has now become a valid choice, even for larger deployments. The same argument can be made for KVM.
Many vendors offer multiple products and layers of licenses to accommodate any organization. You may want to create a list of the requirements. Such as, how many VMs you need, maximum allowed resources per VM, nodes per cluster, specific functionalities, and then check which of these products best fits your needs. Note: trial periods can be very useful when testing for which hypervisor to choose.
In Closing
This article has explained what a hypervisor is and the types of hypervisors (type 1 and type 2) you can use.
Hypervisor vendors offer packages that contain multiple products with different licensing agreements. You will need to research the options thoroughly before making a final decision. Even though you can migrate between the hypervisors, this can be a tedious and expensive process. It’s best to get this decision right from the get go.
MAIN INDEX of latest speed tests | |||
Originally posted October 12th 2004, by rob-ART morgan, mad scientist The NVIDIA GeForce 6800 Ultra DDL is the new top end 8X AGP graphics card for the G5 Power Mac. It's the only card that will drive the new 30' Apple Cinema Display. But you don't have to have that display to take advantage of the card's speed. You can use it with any display. Though our test unit hasn't arrived yet, with the help of a 'remote mad scientist,' we have some performance data for you. This page has results running on a 17' LCD display at 1280x1024. For results at 1920x1200, see our OTHER GeForce 6800 PAGE. The Unreal Tournament 2004 (UT2004) test was done using SantaDuck LCDBench for at Maximum Settings. We chose the FLYBY posted above because it's one of the best ways to measure the contribution of the GPU over the CPU. In the graph below, we show the BOTMATCH using the same tool and settings. It is a CPU 'bound' test, so it makes little or no difference what card you use. Halo tends to use a combination of CPU and GPU to do its thing. We either turned on or set 'high' every feature to stress the GPU. The exceptions were Lens Flare, Sound Quality, and Sound Variety which we set to low since those are CPU functions. In consultation with the Halo developers, we came up with these settings to stress the graphics cards: (* At the suggestion of the Halo developers, we made two kinds of runs with the GeForce 6800 -- one using NVIDIA NV and Vertex Shaders and one using ATI Pixel and Vertex Shaders. Note that ATI shaders produced the higher frame rate.) Quake 3 Arena fans will be happy to know that it ROCKS on the GeForce 6800: Motion is the newest test of graphic cards. As you can see below, how fast you can render a project for preview depends on your graphics card's speed as much as it does on your cpu speed. A G5/2.5GHz Power Mac with a GeForce 6800 renders the 300 frame 'Fire - Mortise 2' template 38% faster than the same computer with a Radeon 9800 XT and 86% faster than the same computer with the Radeon 9600 XT. That's almost like having a third CPU. GRAPH LEGEND CONCLUSIONS Being a 'madman' for speed, I am definitely lusting over this card. However, be aware of the fact that it 'eats' one of your PCI-X slots. The large heatsink/fan assembly encroaches on the PCI-X slot adjacent to the AGP slot. So if you are depending on having all three PCI-X slots available for use in your G5, this is not the card for you. Ditto for the Radeon 9800 XT. That might be why Apple is offering the Radeon 9800 Pro SE as a kit. If you are one of those who bought the RocketRAID 8 port SATA PCI-X adapter, you might still be able to route the data cables out through the back of slot 2 with the backplate off. Is the $599 aftermarket GeForce 6800 kit worth 50% more than the Radeon 9800 Pro Special Edition kit to get up to 115% more 3D game speed. Yeah. Is the Configure-To-Order (CTO) $450-$500 GeForce 6800 worth 41%-50% more than the CTO Radeon 9800 XT to get up to 102% more 3D game speed. Duh. It may seem cheaper if you buy the GeForce 6800 as a CTO option on your new G5 -- but remember, that $450-$500 addon price includes the 'credit' for the Radeon 9600 XT or GeForceFX 5200 it replaces. Hmmm. That gives me an idea: Why not sell your old card on eBay to help recover some of the cost of your 'smokin' GeForce 6800? FLASH: ATI showed off a Radeon X800 graphics card running on a G5 at the Digital Life Expo in New York this week. It only uses one slot and they are confident will match the performance of the GeForce 6800 Ultra. We hope to verify that soon. CAUTION: I've been informed that a bunch of guys who got their 6800's are reporting that the card causes OS X 10.3.5 or lower to crash if the driver is not installed. This means that the Apple Install DVD is useless with the card in the slot. It also means that you can't reinstall the OS or fix permissions while booting off the DVD. It's probably a good idea to install the driver before you install the card. Then I suggest using Carbon Copy Cloner to make a back up drive that can booted from with the card installed. You may also want to make a bootable Install DVD as suggested on Blargatron. RELATED ARTICLES WHERE TO BUY FAST GRAPHICS CARDS If you already own a G5 Power Mac and want to upgrade to the 9600 XT or 9800 XT, you can't. They aren't available as kits from Apple (yet). And they aren't in retail channels (yet). Apple's Online Store does, however, sell aftermarket kits for the Radeon 9800 Pro 'Mac Special Edition' ($399) and the GeForce 6800 Ultra DDL ($599). There are various resellers carrying the Radeon 9800 Pro Mac Special Edition. Buy.com has it and it qualifies for the $10 off coupon and free shipping. Check also with Other World Computing and Small Dog Electronics. If you own a G4 Power Mac with a 2X or 4X AGP slot, your best option is the Radeon 9800 Pro Retail Edition (128MB). I included it in the test graphs above so you can see that it is almost as fast as the other Radeon 9800 models. It is also at Buy.com and also qualifies for the $10 off coupon and free shipping. Check also with Other World Computing or Small Dog Electronics or the Apple Online Store. If you own a Power Mac with only PCI slots, you might want to upgrade to the Radeon 9200 Mac Edition. But read my report on that card first. Has Bare Feats helped you? How about helping Bare Feats? | |||
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