FAQ: Virtualization - What is it?

[sabregen]

For those of you new to virtualization, or just new to this subforum (I guess that includes everyone, since it’s brand new), I’m going to ask for suggestions on what to include on this FAQ, but I’ll kick in some of my own information, as I am recently a VMWare whore, having just achieved VCP certification, myself. To start off, for those that are utterly new to all of this, I’ll give some background information on what virtualization is, and why you’ll be interested. However, as the majority of my knowledge is confined to VMWare solutions, I will stick to that. Anyone more familiar with Xen, Virtual PC, Virtual Server, and Windows 2008 Hyper-V should chime in with their information.

Virtualization – I’ve heard about it, but what is it, and what does it mean for me?

Simply put, virtualization is way of running an operating system on a set of “virtual hardware.” Many here will be familiar with Daemon Tools, and how it creates a virtual optical drive that you can then mount image files to, and the computer thinks it’s running from an actual optical drive. Virtual machine hardware is the same thing, essentially. It is a set of virtual devices that are presented to a virtual machine, which then is running an operating system. Currently, we can virtualize four things: CPU, RAM, HDDs, and NICs.

The reason virtualization is interesting to most people is that it allows you to specify a set of virtual hardware for a designated virtual machine. I can explain this over and over, and get increasingly more complicated in those descriptions, but sometimes, a picture and a caption is really the best way to do it. Without further adieu, I present my streaming media virtual machine's hardware, courtesy of VMWare Workstation:

I've obviously given this VM 2GB of RAM, an 8GB hard drive, an optical drive, a floppy drive, a NIC, USB, a sound card, a display adapter, and 2 CPUs. I've done this all for many reasons, but the important thing for you to know is that this is the hardware that the virtual machine thinks it has when you're installing your OS. It would be just like if you had a dual core machine with 2GB of RAM, an 8GB hard drive, a NIC, a floppy, a video card, sound, USB, and a DVD drive...this is no different. The OS has no idea it's being virtualized (some do, but Windows doesn't), and acts just as it would if it were a physical machine with the same hardware. You update it the same, you install programs the same, etc.

The real interesting part is, say you have a system like mine (not going to list them all), specs are:

2x Socket 1207 AMD Opteron HE8346 (quad 1.8's) = 8 cores
4x2 DDR2 ECC Registered RAM = 8GB
2x 10k 2.5" SAS drives for Vista Ultimate x64 boot
6x320GB 320gb WD AAKS in RAID-5

If I give a VM 2GB of RAM and 2 CPUs, then my physical machine that's running Vista Ultimate x64 pages out 2GB of RAM, and the CPU cores (just like anything else mutli-threaded) will get scheduled to the VM when it needs them. The VMs "hard drive" is actually a flat file on any storage medium I decide to use (that can hold the file). In my case, my VM hard drives are just VMDK files in a "Virtual Machines" directory on my RAID-5 array. The virtual machine has no idea what's going on, that it's hardware is not real, or that it's running in a virtual environment.

If it hasn't clicked yet, the biggest reason behind virtualizing is that it allows you to do more with less. I can run 3 dual core, 2GB VMs on my machine without issue, and taking no performance hit in day to day tasks as I use the machine. You can also do what's called "over subscription" on your physical resources. I have 8GB of RAM, but I could easily create 5 virtual machines that had 2GB of RAM. What happens when I do that? Vista Ultimate x64 (my host OS) does what it would do for any other application when it's requesting access to more RAM than I physically have...it uses the page file. People are using virtualization for everything from doing test setups to development work, to server consolidation, or just goofing around. The time has come where it's no longer a technology that's in the hands of companies that can afford to spend a half of a million on a new server.

I will give you a for example on the consolidation possbilities. This is not a "best case scenario" like a vendor would tell you is capable of achieving, either. We have a financial institution that in the past year has moved almost whole hog to virtualized infrastructure. They have their main datacenter inside of their main offices. The datacenter used to contain 11 racks of equipment...disk, networking, UPS's, etc. They had over 100physical servers. Today, they have less than half of that number. They are running over 50 virtual machines on two physical servers. Now, the servers are definately heavy metal boxes, but in comparison to the previous setup they had, they no longer have to think all that much about downtime for maintenance and upgrades on their machines, and they only have 2 physical servers to maintain and upgrade (for now). Their consolidation rate? 26 physical servers into 1 new physical server, using virtualization. They told me flat out that their savings in heating and cooling alone, for 2008, paid for the new servers. THIS is why companies are interested.

So when did all of this happen, what lead up to now, and why is it something I keep hearing about? What changed?

IBM started the virtualization thing back in the 1960’s using mainframes. If you’re my age or older (I’ll be 30 in a year and half) and you’ve worked in IT as much as I have, you no doubt worked for a company at one time or another that had (whether operational or not) a mainframe of some size and capacity, with users banging away at “dumb terminals.” The idea behind this model is that all of the “dumb terminals” were essentially just input and display devices to a remote session that was actually running on the mainframe, or other backend server.

About 10 years ago, IT saw the proliferation of cheap “commodity servers.” Most people in the industry call them “pizza boxes,” because whether it’s Dell, HP, IBM, or whomever, a 1U server from any vendor is likely:

1) Not very powerful
2) Not expensive to maintain
3) Not very expensive in overall cost to own

So what we saw was everyone saying to their bosses “we can get a server for X, and one for Y, and one for Z.” The prices had come down so much that what was previously a hardware purchase that came under intense scrutiny was now a pittance in comparison. This is what a lot of people at the time called the “holy grail” of computing. 1 task: 1 server. However, as it has already been said, none of these machines were very powerful, nor very expensive. Companies bought 1U servers like they were going out of style in the pre-dot-com bust years, and this was really apparent when the companies tanked, and had a crap load of machines to sell as they were liquidating.

Well, without rambling on too much, computing has essentially gone from those cheap single or SMP chip based 1U’s to having a much more dense and powerful backbone. The advent of multiple core CPUs has really driven a paradigm shift from what was mainframe computing, to pizza boxes, and now back to a more monolithic approach. There’s many reasons for going back to the old model, and virtualization plays off of almost all of them, increasing a company’s ROI on the hardware they just bought.

The top reasons I see from client for heading towards virtualization are these:

1) With more powerful servers, and fewer of them, hardware maintenance costs have decreased
2) Annual maintenance renewal is decreased because of fewer boxes to support
3) Heating and cooling loads in the datacenter have been reduced by decommissioning the many smaller servers in favor of fewer larger ones
4) Power bills for the datacenter have gone down. If there are less boxes drawing power and converting it into heat that must be dealt with, many clients see as much as a 60% drop in their power bills
5) Companies are able to more effectively utilize their hardware in the datacenter, literally pushing the servers to a point that would otherwise not be achievable
6) Companies are released from their reliance on specific sets of hardware for production servers.
7) Allows better usage of servers. Typical datacenters are filled with machines that usually are running under 20% utilization. Consolidating many into one has many advantages.

Datacenter virtualization contrasts with desktop virtualization by quite a lot. In the desktop space, you only need to have a functional host OS to run virtual machines. In the datacenter, and more specifically, in bare metal hypervisor implementations, there’s strict hardware platforms, devices, and drivers that are certified by the company providing the bare metal hypervisor. Although your server may run *Nix or Windows just fine, it may not be a candidate for a virtualization host.

Okay, but that was all datacenter stuff, what about me at home and desktop solutions?

Here’s where the rubber really is meeting the road, and all of the previous information regarding the application to companies and datacenters really comes into play. As I said before, the advent of commodity pricing on hardware, and the release of multi-core CPU solutions into the mainstream market mean that no longer are datacenters the ones with decent computing power. The desktops of today have more power in, say an Intel Q6600, than clusters of dozens of machines from 10 years ago. This has unleashed the capability of the datacenter (to an extent) on the home market.

The desktop solutions that are available today are largely free, with a few exceptions, which has really only served to further penetrate the market. Virtualization is probably the single biggest buzzword I hear now at work. Those that don’t know what it is want to know, and those that know are either already doing it, or are budgeting for it. At home, you can play with it for free (and I’ll go over those options in a bit), and probably on the hardware that you’ve already got.

Desktop virtualization does differ from the datacenter virtualization in a few key areas, and it’s important to understand the terms and what the differences are, so I’ll attempt a quick overview (which will likely get filled in with more data later on). Desktop virtualization is a “hosted” virtualization environment. When you run something like VirtualPC or VMWare Workstation, you’re running an application inside of your host OS. You’d fire up your OS, as usual, and your virtualization application would be installed like any other application on that system. When you fire up the application of your choice, you’d then be presented with the ability to run virtual machines that you had created. In desktop virtualization, there are no stringent hardware requirements to get the virtualization wheel moving. The application uses the “host OS” underlying drivers to know what it’s running on. If your underlying OS is working fine, you’re all set. In the datacenter, it’s a whole different ballgame. The virtual machines that you create in this scenario make driver calls to the host OS, which then handles them appropriately.

Emulation versus Virtualization...what's the difference?

This is another good question, and I'm strong these days with my Google-Fu. I'm not going to re-create the wheel, so I'm stealing again (with credit, of course): http://blog.1530technologies.com/2006/08/virtual_machine.html

Emulation - involves emulating the virtual machines hardware and architecture. Microsoft's VirtualPC is an example of an emulation based virtual machine. It emulates the x86 architecture, and adds a layer of indirection and translation at the guest level, which means VirtualPC can run on different chipsets, like the PowerPC, in addition to the x86 architecture. However, that layer of indirection slows down the virtual machine significantly.

Virtualization - on the other hand, involves simply isolating the virtual machine within memory. The host instance simply passes the execution of the guest virtual machine directly to the native hardware. Without the translation layer, the performance of a virtualization virtual machine is much faster and approaches native speeds. However, since the native hardware is used, the chipset of the virtual machine must match. Usually, this means the Intel x86 architecture. VMWare is an example of this type of application for Windows.

 

[sabregen]

I hear a lot of terms being thrown around in all of this virtualization discussion, and I don’t know what a lot of them are.

Understandable, and I’ll hopefully be able to fill in some of the gaps. I am also open to recommendations, information, suggestions, etc. We’ll try to keep this on virtualization and its associated technologies. I’m not trying to cover all of IT here

VMWare – a company that is now owned by EMC. They have been producing virtualization technologies for the datacenter for about 10 years now. They make several products of varying capabilities, some for the datacenter, and some for the desktop. If you hear virtualization, it’s almost guaranteed that you will also hear this company’s name mentioned. They currently hold the largest of the market share.

ESX – One of VMWare’s products for the datacenter. ESX is a bare metal hypervisor. This means that instead of installing Windows or *Nix on the server, you’d install ESX instead. ESX has a lot of features (which I could expand on greatly, and can if requested) for the datacenter admin. This product contains a service console, so it can be administered through the CLI. It runs on an x64 Linux 2.4 kernel that is believed to be a modified RedHat kernel, although VMWare denies this, claiming they built it from the ground up. The basic version of ESX runs about $1500 to start. ESX can give a virtual machine up to 4 CPUs and 16GB of RAM.

ESXi – This is similar to ESX (and is also for the datacenter), but does not contain a service console. Administration is a little less complex, due to the lack of the service console. Because it has no service console, you will typically see ESXi deployed in datacenters that require more security. ESXi can function in multiple host configurations just as ESX can, provided that the licensing to do so is valid. ESXi actually has two versions, an installable and an embedded version. The installable version is just like any other OS, residing on hard drives. The embedded version runs from a VMWare and server OEM certified USB key that is encrypted, and serialized to the motherboard that it is running on. While this may sound appealing, it introduces an array of availability and failure rate concerns for many systems administrators (myself included). The installable version of ESXi is now free. The USB version can only be purchased in conjunction with a new server, and the charge is about $500-600. ESXi can give a virtual machine up to 4 CPUs and 16GB of RAM.

Hypervisor - There are two types of hypervisors currently, oddly enough, called Type 1 and Type 2. They both essentially provide the same end result, which is to allow multiple operating systems to run on the same physical machine, simultaneously. Futher definition of Type 1 and Type 2 hypervisors:

Type 1 - runs on bare metal. A Type 1 hypervisor IS the operating system that the physical machine is running. It intercepts all resource request from the guest operaing systems. In most cases, the use of the term "hypervisor" is meant in this context, a bre metal installation of software on a physical machine that provides an abstraction layer between the underlying hardware, and the guest operating systems that are running on it. A Type 1 hypervisor usually has a faily stringent, and qualified set fo hardware platforms that it will function on. This is because the Type 1 hypervisor has to be able to directly control the underlying hardware that it is running on.

Type 2 - runs in a hosted environment. A Type 2 hypervisor runs as an application installed on an existing operating system. This also intercepts calls from guest operating systems and interprets the reousrces to be allocated to facilitate the requests. The main difference between this hypervisor and the bare metal version is that here, the abstraction layer is making calls to the host OS's drivers, instead of managing the resource requests and underlying hardware, itself. Type 2 hypervisors, because they run in a hosted environment, do not have the hardware comaptibility requirements that Type 1 hypervisors have.

VMotion – This is a licensed feature for ESX or ESXi. This allows running virtual machines to be moved from one host machine to another, without taking the virtual machine offline. This feature is also leveraged for DRS and HA. When people talk about maintaining uptime, it is specifically this function that provides the uptime they are referring to. You can, for instance, take a virtual machine running on one server, and move it to another, without anyone knowing its happening. This allows for planned hardware maintenance on servers without having to work after hours, or on weekends.

Storage VMotion – Another licensed feature of ESX or ESXi. This allows you to move the virtual machine’s hard drive files from one storage location to another. Similar to VMotion, Storage Vmotion allows for easy migration of currently running virtual machines from one storage solution to another, without ever taking the machine offline.

High Availability (HA) – Referring specifically to VMWare’s licensed feature in this description, HA is a configurable setting that allows for the creation of host clusters in the ESX or ESXi environment. Specifically, it allows you to configure how many host failures can be tolerated in a given cluster of hosts. It also allows you to configure what the response of the hosts that did not fail will be. One key feature here is the ability to configure the action to be taken with regard to virtual machines that were previously running on the now offline host (in the case of a host failure).

Dynamic Resource Scheduling (DRS) – this licensed feature of ESX or ESXi has multiple settings, but the basic idea behind any of the configurable settings is the same – what should a host machine do when it is overloaded, but other servers in the cluster are not. DRA can be configured on several variables to migrate machines off of a host in the cluster, using VMotion, to more evenly balance out the load being incurred.

Virtual Center Server – this is more of a collection of features that anything else, and serves several functions in the ESX and ESXi environment – to maintain order among the hosts. If the hosts are the muscle, Virtual Center is the brain. It has several key components, including:
1) Database
2) License server
3) Background services

It should be noted that although Virtual Center can run on a physical machine or a virtual machine, it can only run on Windows, something that draws much ire from datacenter and systems administrators, particularly the ones that are all *nix houses. Virtual Center, when deployed, is the machine that you log into to control your ESX environment. It handles the scheduling of the host resources in the ESXi or ESXi environment. You must have a Virtual Center server in your environment to use all of the "cool" features with VMWare. HA, DRA, VMotion, Storage VMotion all require a Virtual Center server installation to function.

VMWare Workstation – this is a desktop virtualization solution, and is a licensed product. Currently, there are Linux and Windows versions of VMWare workstation available for purchase. I do not know the current pricing on this. The limitations of VMware workstation are 2 virtual CPUs and 8GB of RAM. Apparently, you can run a 32bit host OS, and then run a 64bit guest OS, if you have a 64bit platform capable of virtualization acceleration (thanks unhappy_mage).

VMWare Server – the free version of VMWare’s desktop virtualization solution. Although it lacks a few control features of Workstation, most home users or beginners to virtualization would not notice the difference. This is a good place to start with virtual machines. Apparently, you can run a 32bit host OS, and then run a 64bit guest OS, if you have a 64bit platform capable of virtualization acceleration (thanks unhappy_mage).

VMWare Fusion - this one caters to the Macintosh crowd (and I pretend to forgive them for it ). This is a licensed product, just like Workstation is, and acieves the same functionality.

Host OS - only valid in a desktop operating environment, the host OS is the underlying operating system installed on the machine, which will typically be a *Nix or Windows installation for most people. It's not really important to know anything about the host OS, other than what people are referring to when they day it. If someone says "Host OS" in reference to a virtualizing discussion, it's inferred that they're doing desktop virtualization of some sort.

Guest OS - also in desktop virtualization, the Guest OS is merely the operating system that is being run inside of the virtual machine. This could be any number of supported (or perhaps unsupported OS's...I virtualized an ESX server ) operating systems running on a Host OS. Again, when someone say the "Guest OS" in reference to a virtualization discussion, they're talking abouit the OS running on the virtual machine.

People are talking about full virtualization and paravirtualization..what do they mean?

There's two main ways right now to do virtualization. One is full and the other one is para. Here's what they're talking about (admittedly stolen from here): http://blog.taragana.com/index.php/...ll-virtualization-versus-para-virtualization/

Fully virtualized - Full virtualization provides total abstraction of the underlying physical system and create a complete virtual system in which the guest operating system can execute. No modification is required in the guest operating system or application; the guest OS or application is not even aware that it is running within a virtualized environment. The guest OS executes on the VM just as they would on a physical system. This approach can be advantageous because it enables complete decoupling of the software from the hardware. As a result, full virtualization can streamline migration of applications and workloads between different physical systems. Full virtualization provides complete isolation of different virtualized applications, which makes this approach highly secure by design. Microsoft Virtual Server and Vmware ESX Server are examples of full virtualization.

However full virtualization may incur performance and resource penalty. The Virtual machine monitor must provide the VM with an image of an entire system, including virtual BIOS, virtual memory space, and virtual devices. The VM monitor must also create and maintain data structures for the virtual components, like memory page table. These data structures must be updated for every corresponding access by the virtual machines.

Para-Virtualization -
In contrast, para-virtualization presents each virtual machine with an abstraction of the hardware that is similar to but not identical to the underlying physical hardware. Para-virtualization attempts to provide most services directly from the underlying hardware instead of abstracting it. Para-virtualization allows for near-native performance.

Para-virtualization requires modifications to the guest operating systems that are running on the VMs. As a result the guest operating systems are aware that they are executing on a VM.

The term "paravirtualization" was first used in the research literature in association with the Denali virtual machine monitor. The term is also used to describe the Xen, L4 and TRANGO hypervisors. All these projects use paravirtualization techniques to support high performance virtual machines on x86 hardware by implementing a virtual machine that does not implement the hard-to-virtualize parts of the actual x86 instruction set.

Para-virtualization is developing field and may have potential security issues with guest OS cache data, unauthenticated connections etc.

What does it look like on my desktop?

It looks like this! This is an XP 32bit VM that I have running in VMWare Workstation on my laptop. I am running this VM because my host OS is Vista Ultimate x64, and I need to be able to use the Cisco VPN software for when I am doing admin work from home, or somewhere that's not the main office. Unfortunately, Cisco apparently has no plans to make an x64 VPN client, so I have to run a VM. I fire up my laptop, fire up VMWare Wrokstation, power on the the XP VM, and then launch the Cisco VPN software. Once I'm connected through the VPN in the VM, I can do anything in that VM as if I was at work, running XP. The side effect of running the VPN inside of a VM is a nice one...usually when you VPN into another network, all of your traffic all of a sudden is going through that VPN connection. This is still the case when you run VPN inside of a VM, but now the only traffic that's going over the VPN is the traffic inside the VM. The host OS is still maintaining the same connection that it's always had. I can run a VM and be on the VPN, and still get to my other machines on my home network, because the only traffic that's tunneling is the traffic from the VM, if that makes sense. Here's a screenshot:

 

[number69]

Nice post. Another good reason for virtualization is testing an OS, any software that will run on it..etc.. which should be pretty obvious.

 

[SockMan!]

Also note that when people speak of Virutalization in general, they are usually talking about OS virtualization (such as running Windows in a VMWare virtual machine). However, Virturalization can happen at many different levels other than an entire machine - such as a virtual hard drive over a SAN.

 

[sabregen]

number69 - thanks. I'll need to update it as my brain clears, and as I get more feedback. You're right though, virtual machines do definately assist in dev & test environment work for a growing number of people and companies. Just last night I built a Vista 32bit test VM, to make sure that I understoof how to properly link a MyMovies client to my configured database, and make sure that I had all of the UNC paths correct. No drivers to install (just VMWare Tools), and didn't even bother updating with Microsoft, just installed and tested. Now I have a good baseline for rebuilding my HTPC, and I know exactly what I have to do.

SockMan! - no doubt you are 100% correct. However, the thread will hopefully serve as a jumpoff, and perhaps we can cover sotrage virtualization here in a little bit. I suppose I should add that to the list?

 

[rgratto2]

I feel as though you need a more concise sentence or two in your opening paragraph about virtualization that details its main usage - its ability to virtualize the hardware to allow for multiple operating system installations to run simultaneously on a physical machine.

I was reading through it and kept waiting for that sentence where a reader who was learning about it for the first time would be like "oh, so that's why I would do this..." I feel like you were getting too far into the details without giving a definitive summary of the topic.

 

[pfunkman]

Nice work!

 

[sabregen]

I feel as though you need a more concise sentence or two in your opening paragraph about virtualization that details its main usage - its ability to virtualize the hardware to allow for multiple operating system installations to run simultaneously on a physical machine.

I was reading through it and kept waiting for that sentence where a reader who was learning about it for the first time would be like "oh, so that's why I would do this..." I feel like you were getting too far into the details without giving a definitive summary of the topic.

I'll +1 this myself. I think you've hit the nail on the head. Thanks.

 

[Hurin]

I'll +1 this myself. I think you've hit the nail on the head. Thanks.

In the "a picture is worth a thousand words" mode of thinking here. . . some type of screenshot with a windows desktop running a few virtualized OSes in windows would probably work wonders in making that light-bulb pop on over people's heads.

 

[sabregen]

In the "a picture is worth a thousand words" mode of thinking here. . . some type of screenshot with a windows desktop running a few virtualized OSes in windows would probably work wonders in making that light-bulb pop on over people's heads.

Indeed, you are likely correct, and I was actually just thinking that while I was adding content. I'll get cracking...since I just decided that I wanted to use Vista on my streaming machine instead of XP...I'll have a go from the beginning.

 

[Gorankar]

deleted by gorankar

 

[nitrobass24]

Sabregen I think its time for some more tutorials

I was thinking about making a Windows Hyper-V Server tutorial(just started playing with it but it seems pretty cool).
Maybe you could do an ESX tutorial(since that is your expertise)

 

[The_Mage18]

I think you should include a small section regarding para-virtualization and what the difference is between para and full. Also, you're incorrect regarding Windows and virtualization. Windows server 2008 is fully virtualization aware. Windows server 2003 and Windows XP can be partially para-virtualized using Novell's Virtualization Driver Pack and their implementation of XEN Virtual Server.

 

[sabregen]

Sabregen I think its time for some more tutorials

I was thinking about making a Windows Hyper-V Server tutorial(just started playing with it but it seems pretty cool).
Maybe you could do an ESX tutorial(since that is your expertise)

I probably could, now that you mention it, since I've managed to virtualize it, it would be trivial.

 

[sabregen]

I think you should include a small section regarding para-virtualization and what the difference is between para and full. Also, you're incorrect regarding Windows and virtualization. Windows server 2008 is fully virtualization aware. Windows server 2003 and Windows XP can be partially para-virtualized using Novell's Virtualization Driver Pack and their implementation of XEN Virtual Server.

You're right, adding information between paravirtualization and fully virtualized environments would be useful. I'll have to add that to the list of ideas to cover. Thanks.

Well, you're correct regarding the additions available for Windows 2003 and XP from Novell under Xen, however, the statement that I made is also true. The operating systems themselves are completely unaware of what's going on. They require the addition of non-Microsoft software in a specific Xen environment to achieve that level of functionality.

Also, Server 2008, itself, runs in a Hypervisor. Technically, it is aware of virtualization takign place, however, since it itself is virtualized, that sort of creates a conundrum to try and explain, and is beyond the scope of a newcomer's understanding (IMO, and I am making assumptions, admittedly).

 

[The_Mage18]

Also, Server 2008, itself, runs in a Hypervisor. Technically, it is aware of virtualization takign place, however, since it itself is virtualized, that sort of creates a conundrum to try and explain, and is beyond the scope of a newcomer's understanding (IMO, and I am making assumptions, admittedly).

Awwwww come on! I want to watch the glazed over look in their eyes and hear the POP when their brain snaps!!

I agree though, that would be a bit much to try and explain. Minus the para-virtual part, ignore the rest of my previous post.

 

[sabregen]

...you should have seen my face the first time I tried to comprehend how virtual center could be a vm running on a physical host...that it was managing. I just about caved.

EDIT: This post made [H]ardness Supreme official. SWEET

 

[sabregen]

updated the pics and info on running a VM in a hosted environment. I'll add full virt vs para virt info here in a bit

 

[sabregen]

added full versus para information to post #2

 

[mightydarv]

Just wanted to drop a quick thank-you note in here, as I have the sneaking suspicion I'll be hanging out in here lurking a good deal. I do a lot with virtuals at work, and having a forum here where I can pick the brains of people far smarter will be a very nice thing. Also, I'm looking forward to picking up some VMWare info as I have almost exclusively used Microsoft solutions up until now, and we are talking about expanding into VMWare support.

 

[rgratto2]

Oh wow its come a long way in a short time, good work!

 

[sabregen]

thanks. I try to keep myself busy

 

[unhappy_mage]

VMWare Server ... In order to run an x64 guest OS, you must be running a compatible x64 host OS.

Not true. I've run a 64-bit Linux guest on 64-bit hardware with a 32-bit Linux on it. See VMware's FAQ on this.

 

[sabregen]

so you are saying that your configuration was as such:

Linux 32bit Host OS running VMWare Server
Guest OS running Linux x64

I followed the link, and read the whole thing, but I could not find the specific example that seemed relevant to how this is achieved. I could have just missed it. The second question I have is...why?

 

[pfunkman]

Not true. I've run a 64-bit Linux guest on 64-bit hardware with a 32-bit Linux on it. See VMware's FAQ on this.

Your link contains absolutely nothing to support what your saying. In fact it has nothing to do with Host OS requirements.

I would really be interested in how you did it though.

 

[SockMan!]

You may want to briefly discuss emulation: what it is, how it's different from virtualization, why you can't virtualize a PlayStation on your PC, etc.

Also, you should add a definition for "hypervisor".

 

[sabregen]

You may want to briefly discuss emulation: what it is, how it's different from virtualization, why you can't virtualize a PlayStation on your PC, etc.

Also, you should add a definition for "hypervisor".

good suggestions. Thanks, I'll get on it.

Although, You can emulate a Playstation on PC, you're right in saying that you can't virtualize one.

 

[unhappy_mage]

so you are saying that your configuration was as such:

Linux 32bit Host OS running VMWare Server
Guest OS running Linux x64

Exactly.

I followed the link, and read the whole thing, but I could not find the specific example that seemed relevant to how this is achieved. I could have just missed it. The second question I have is...why?

Well, as long as the hardware requirements are met, the software works fine. As for why: Some devices have only 32-bit drivers, so you can run a 32-bit OS on the hardware and still use 64-bit guests. 64-bit guests are useful for testing platforms; if you need to check if your software works on 64-bit machines you can do so.

Your link contains absolutely nothing to support what your saying. In fact it has nothing to do with Host OS requirements.

I would really be interested in how you did it though.

The host OS doesn't factor into it. VMware switches the processor in and out of 64-bit mode.

Here's a link to the VMware forums. They don't say much about the subject other than "it works"... because it just works.

 

[sabregen]

and how's the performance on that type of implementation? I would expect to see a performance hit for doing the mode switching on two actively running OS's.

Also, does this only apply to VMWare Server, or does it also apply to their other hosted solutions, like Workstation for Windows, Linux and VMWare Fusion?

 

[sabregen]

update. I pegged the 20,000 character per post limit in post #1, and am having to move some stuff to post #2 to accomodate the requests. I wonder if I can get a post or two inserted!? I'll have to ask.

 

[unhappy_mage]

and how's the performance on that type of implementation? I would expect to see a performance hit for doing the mode switching on two actively running OS's.

I haven't done any performance tests, so take it with a grain of salt... but you're already doing sort of a super context switch to do 32-on-32 virtualization. I wouldn't expect 64-bit to be much more expensive than that, but I don't know what is entailed in switching from 32 to 64 bit mode.

Also, does this only apply to VMWare Server, or does it also apply to their other hosted solutions, like Workstation for Windows, Linux and VMWare Fusion?

As far as I know. VMware Workstation and Fusion explicitly mention 64-bit support on their respective pages.

 

[sabregen]

Yes, I know that you can both support 64bit OS's, but my specific question was whether you knew if they supported 64bit OS's on 32bit hosts, as you have stated that Server does.

 

[Vader]

Ahh...I see the dreaded Cisco VPN client forced an XP VM...lol....i'm in the same boat...

 

[MrMike]

Ahh...I see the dreaded Cisco VPN client forced an XP VM...lol....i'm in the same boat...

As soon as I saw this I thought, "Now we just need a screenshot of one with the Nortel client in it also."

Wtf is wrong with these companies? lol.

 

[sabregen]

Well, in my case I can;t use the web SSL client on our ASA to achieve what I need when I am away from the office, so I have to run the damned client...and Cisco can kiss my grits for not having a 64bit client.

 

[QHalo]

Well, in my case I can;t use the web SSL client on our ASA to achieve what I need when I am away from the office, so I have to run the damned client...and Cisco can kiss my grits for not having a 64bit client.

F'in A about the 64bit client.

 

[Dan_D]

I use this quite a bit at home on my Skulltrail setup.

 

[sabregen]

You use use the Cisco client or VMs?

 

[kencheeto]

FYI small syntax mistake in the first sentence, second paragraph after you list your specs- 'less with more' should be 'more with less' .. I think.

Just thought you should fix it- I don't know a thing about virtualization, overall a decent introduction. Might want to include some examples of why normal home users would use VMs, such as various [H] users who don't already use VMs at work.

 

[Gott]

When I need to VPN into work on my home machine, I fire up my XP VM to make the connection.