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An Overview of Virtualization
Posted by
kdawson
on Tue Jan 02, 2007 02:47 PM
from the next-big-old-thing dept.
from the next-big-old-thing dept.
IndioMan writes to point us to an overview of virtualization — its history, an analysis of the techniques used over the years, and a survey of Linux virtualization projects. From the article: "Virtualization is the new big thing, if 'new' can include something over four decades old. It has been used historically in a number of contexts, but a primary focus now is in the virtualization of servers and operating systems. Much like Linux, virtualization provides many options for performance, portability, and flexibility."
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virtuosity (Score:4, Funny)
That article had the virtue of being a virtual cornucopia of information.
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Virtualization is so easy (Score:2, Funny)
QEMU (Score:3, Informative)
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Just wanted to point out that qemu can also do virtualisation on Linux, just like Vmware, with a closed-source kernel module.
The article lists the following solutions on Linux: Bochs, QEMU, VMware, z/VM, Xen, UML, Linux-VServer, and OpenVZ. I'm not sure why you felt the need to mention QEMU specifically. It does, however, seem like one of the more promising solutions. Have you used it in production?
Re:QEMU (Score:5, Informative)
I suspect because the article incorrectly describes it as an emulator, while it is capable of full virtualization if the plugin the GP post linked to is used.
It's not the only such mistake in the article: Xen is described as performing paravirtualization, but it too is capable of full virtualization in some cases (i.e., when it is supported by the hardware).
Parent
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The article does one better and specifically mentions KVM+Qemu, but don't take my word for it.
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Apple (Score:5, Interesting)
This article is an okay overview of many of ways virtualization is now being used. As an aside, has anyone else noticed Apple seems to be missing the boat this time? They're certainly benefitting from virtualization with several players in the market providing emulation solutions and tools now that they are on Intel, but Apple themselves seem to have done nothing and not even provided a strategy. Servers are moving to more virtual servers on one real machine, but OS X's license forbids it from fulfilling that role. Tools for using OS X as a thin client for accessing remote virtual machines are likewise weak. Apple hasn't even provided a virtual machine for their customers to emulate old macs so that users can run OS 9 apps on the new intel machines and they restrict redistribution of their ROM files to make 3rd parties unable to do this. No mention of adding VM technology to OS X has been heard, despite its inclusion in the Linux kernel among others.
Does Apple have something against VM technology? Are they simply behind the times and failing to see the potential?
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Re:Apple (Score:5, Interesting)
Virtualization is usless in a desktop multimedia user environment. Video cards, sound cards and the like are bus mastering devices and you cannot virtualize hardware access unless you own the whole environment. In simple terms, virtualization is only usefull in the server arena and useless on the desktop.
As someone with two VMs running on my OS X laptop right now, I'd have to disagree with you. As for sound cards and video cards the sound works just fine and at least two companies I know of are working on support for allowing hosted OS's full access to video card acceleration.
Parent
Re:Apple (Score:5, Insightful)
None of this is hard to figure out. Yes, there are reasons it would be nice, but it's pretty obvious why they're not too keen on it.
Parent
Re:Apple (Score:4, Insightful)
They don't want you to use OS X in a VM, as it makes it trivial to use it on generic PC's, which eliminates the vast majority of their revenue.
I'm sure that is true, but do they have a plan for what happens when/if the industry moves toward virtual machines on the server? Are they just going to let OS X server die, or try to target only really small businesses? What about thin client support? if more and more VMs start running on big hardware and exporting to thin clients do they have a plan to provide better support for those clients? Integrate with those UIs? Are they just assuming none of this will happen?
They don't include virtualization software themselves as Parallels and VMWare are doing a good job if you need such a thing, and they don't want to alienate them.
It is perfectly understandable not to include a VM in their workstation, but that does not preclude kernel level support for virtualization, including API's and hooks for interoperability. What about hooks for supporting virtual machines like Parallels, but treating the apps as more "native" with Windows or Linux binaries showing up as icons in OS X?
And not strictly virtualization, but you mentioned it - they don't want to make it easy to use OS 9.
Depending upon how access to OS 9 apps is accomplished, it certainly is virtualization. I certainly understand not including it in a the default install to discourage the use of OS 9 apps, but making it hard to find and install your own VM of this sort is counterproductive, in my opinion. Even PS3's provide a way to run PS2 games.
Meanwhile, they do nothing to hinder or help SheepShaver and others; the ROM files needed are available from Apple's website (although not easy to find).
SheepShaver is useless without ROMs, the discovery of, extraction of, and installation of is well beyond the capabilities of even many advanced users. Apple does not allow the SheepShaver project to redistribute those ROMS or include them in a pre-build binary. That certainly hinders the project a lot and prevents it from ever being user friendly enough to attract a significant body of developers. It seems like a tiny bit of privilege from Apple would go a long way here, but they withhold it.
It just seems like VM is a very promising new technology that MS and Linux distros are leaping at, and which is finally evolving a few standards. Ignoring it on so many fronts, seems dangerous to me, akin to MS ignoring the internet until the final hour. Ignoring some of the fronts on which VM is making inroads is one thing, but ignoring them all seems almost like a cultural bias. I wonder if maybe the term is taboo at Apple, since they are worried about it one one front and have applied a policy a little too liberally.
Parent
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OK, your other points aside, I got a full-body shivering skeeve with a bit of throw up in my mouth when I had a mental picture of usually-very-nicely designed OSX icons sitting right next to the crap you get on Windows and Linux.
Be that as it may, it makes sense for end users and maintaining a consistent paradigm is important especially for novice users.
Sandbox==good. That way you can keep all the turds in the same place.
I'm all for sandboxing applications, even native ones. I think it is going to ha
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In my humble opinion, OS 9 needed to get the boot. Very few people depend on classic apps, and maintaining the classic environment is just another damn thing to chew up development resources. Yet, this is becoming more of a topic of emulation then virtualization.
The big thing for consumers is Windows virtualization on OS X. It's a cool concept, yet it's a human factors nightmare and not
Thanks, IndioMan & kdawson (Score:2)
No, it's not red-hot, breaking news, but valuable stuff like this is why I keep coming back to this mess (/., I mean). If you're like me and spend most of your Slashdot time reading the comments, take time to read this TFA.
Re:Thanks, IndioMan & kdawson (Score:5, Informative)
For the home user virtualization can be used as a separate PC to surf the net without fear of malware, when you are done surfing just restore the VM to the "clean" state, think "your pr0n browsing PC". You can also use it to test software before contaminating your host PC with stuff you decide not to keep. I visualize it as a sandbox to play in before messing up with the "real" system.
Check the vmware player appliances [vmware.com], there are lots of good ideas there, many of them are for business use but there are several that can be used at home.
For the developer / tester virtualization provides a set of target operating systems to test / debug the software on without need of having the actual physical hardware.
Of course, in the data center it is the next big thing, too many advantages to list here.
Parent
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But I've only now sta
Old New Things (Score:3, Funny)
You just wait. Next thing you know we'll be running Lisp machines under our virtualization software. And then there's going to be a new remake of ADVENT and the Great Worm. And a new AI summer.
another reason why virtualization is so hot (Score:5, Informative)
I work at a small ISV which just bought SourceForge, Enterprise Edition [sourceforge.net] which is an Apache/JBOSS/PostgreSql/CentOS app for managing SDLC. For a company of our size, they package this as a VMWare image. Installation is incredibly easy. I can definitely see how free virtualization can be a big boon to companies selling and/or consuming web applications for small deployments.
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FWIW, there are also GForge [gforge.org] VMWare appliances out there [spisser.it]. I can see how it'd make a normal installation easier to troubleshoot, too, if you had a VMWare installation for comparison.
And of course, it's awesome that they both run on PostgreSQL, great stuff [blogs.com]!
Xen does more than just paravirtualization (Score:3, Interesting)
The article seems a bit light on qemu too.
OSes Targeting VMs (Score:4, Interesting)
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Hey, maybe instead what you could do is create a machine that virtualized the devices and provided some sort of interface that programs could just access directly! Of course, you'd need is some additional interfaces for process creation a
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I have long advocated that, but, for some reason, it won't happen. There are _some_ standards, like VESA, ATA, and various USB device classes (yay!), but everywhere else be dragons: accelerated video, Ethernet, WLAN,
``There should be no drivers in the OS level, custom implementation belongs i
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Missing Mac On Linux (Score:4, Informative)
It'm glad to see similar happening on x86, finally, as it's one of the things that really made PPC based machines special. (There is some documentation for MOL and Kubuntu here [revis.co.uk].)
Security use? (Score:2)
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Sure, you could run every program in its own VM. But why would you want to? You say this further isolates them from one another, but I don't think that's really true. From the top of my head, there are 3 ways programs can affect each other:
1. Through shared memory. *nix systems isolate processes from one another with the aid of a memory manag
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Is it theoretically possible to virtualize a few copies of the OS+BIOS+etc. for each program launched to further isolate one program from crashing/infecting others? Or maybe that'd be way too resource intensive?
It is theoretically possible and it is resource intensive. A more workable solution is simply to build strict application level restrictions into the kernel to prevent applications from interacting, and this seems to be the way modern OS's are heading. A VM is useful for running legacy application
Virtual appliances (Score:2, Insightful)
I for one look forward to vendors coming in and pitching me their software. The ones that can instantly show me the product in a virtualized session running on their laptop will be the ones that we write the check out to.
I for one look VERY MUCH forward to placing our systems on virtualized resour
*Another* Layer? (Score:4, Insightful)
But in theory, it bothers me. The basic idea (as I see it) is to provide an isolated environment for applications to run. But that's what the OS was/is supposed to do in the first place, and typesafe languages (like Java) also do much of the same thing once again! (E.g. I see no inherent reason for virtual to physical address translation when running Java applications). The biggest commercial application I see for virtualization is server consolidation. Why not just run all those server processes within the same OS? Yes there are good reasons, but is virtualization really the most efficient solution to those problems?
Maybe virtualization is the best compromise given the legacy that computing currently has, but I wonder if some clever researchers have expressed a vision of how all the same ends could be accomplished much more simply and consistently. Or do all these layers upon layers of abstraction really provide necessary degrees of freedom?
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It should also be good for those environments that do not require much performance. if you are running a specialized java app and you consolidate 2 hardware solutions into a virtualized solution, you might need to have 2 different java compi
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Because not all server process were written for the same OS.
Granted if the source code is available you might be able to recompile it, but if it is not then you don't have much of a choice to to use the OS it was written for.
You could have one box per OS approach, but due to fact that hardware is become fast enough to make this a moot point and you'll save money on the electric bill alone to make it worth your while.
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Sometimes two pieces of software don't play nicely together, sometimes they're not available for your OS of choice (or the OS of your choice no longer supports any hardware you can still purchase), sometimes it brings the whole system crashing to the ground and you'd like to limit the damage it can do to a single virtual machine running one process rather than a physical machine running many. Or maybe you don't expect ev
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For developers, VMs are fantastic. Not only does it let you target multiple architectures easily, it also makes it possible to create, backup, restore, an
Re:*Another* Layer? (Score:5, Interesting)
Parent
I recently tried to get Vista to work on Xen.... (Score:2, Informative)
Xen on FreeBSD? (Score:2, Interesting)
Tell me where it's useful... (Score:2)
But, virtualization is so often touted as a way to consolidate servers. I keep asking myself "Who are these people that have that many servers with so little load, that many servers that they could consolidate (making a single COMPLETE point of failure), and have
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Where we've found it incredibly useful is in 3 cases:
1) Any server where end users may cause damage. In our case, we have a remote desktop available to the end users via Citrix. Yes, it's secured -- but there's always SOME chance that an end user will mess it up somehow. By running the Citrix server in a virtualized non-persistant environment, any damage can be corrected by simply rebooting the virtual Citrix box.
2) Very low utilization applications
Big New Thing??? (Score:3, Interesting)
Internal: DHCP, DNS, postfix SMTP server for internal clients, Squid proxy, OpenVPN MySQL DB, DBMail IMAP services that use MySQL as the backend. All in 128 megs of RAM. And they all perform smoothly and quickly.
External: DNS, postfix SMTP server for spam filtering and relaying to the virtual internal SMTP server, OpenVPN server. All in 64 megs of RAM.
I plan to add an Asterisk PBX to that same box for a third VPN so I can have private VoIP with my OpenVPN users (all friends and family as I'm talking about a system at home, not at work).
I've, of course also played with Virtual PC, Virtual Server, QEMU and poked at OpenVZ. For me, a decent virtualization solution has to be able to run other OSes to count as good which is why certain virtualization solutions don't do much for me. If I need access to Windows, I want to be able to do it without wasting good hardware on it. That's why UserMode and Linux Virtual Servers (more akin to chroot jails) do absolutely nothin for me other than when I'm building a Gentoo box. But, this is not the big new thing. It's only that MS is making waves with it now... typical.
Microkernels++: Just in case you dont remember (Score:3, Insightful)
It really is a pity we gave the whole project up and decided to just implement YET ANOTHER page table in hardware, rather than try to solve the PIC code layout, IPC performance issues, and wrestle with building a new dynamical component based environment. I think we'd see virtualization on a much more pervasive level and a much stronger conception of mobile code, stretching all the way to embedded devices. As it is, the hardware virtualized environments are so insular from each other that there is a) no reason to run it on embedded systems (since integration is all application level, tracing through pretty meaty stacks) (watchdog systems aside) and b) it would impose colossal power consumption needs for mobile devices since it has to run each OS seperately.
Virtualization as we know it is a terrible terrible excuse for unix never having built itself a sufficiently dynamical and configurable environment. Two thumbs down. As cool as running multiple OS's is, it should not have been necessary in the first place.
LordMyren
Article missing MDF (Score:3, Interesting)
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There is a note of cynicism in your statement, but yes you will need adequate hardware and resources to take advantage of virtualisation. You should not expect to run two identical instances of a server environment on your hypervisor and expect a performance increase (depending on utilization of course). Also keep in mind your host os is going to need resources to run the show. This is where a stripped linux install has the advan
Re:3d? (Score:5, Informative)
Edit your
Add the following:
mks.enable3d = TRUE {- Requires acceleration on the host, because it passes things directly from the guest.
svga.vramSize = 67108864 {- This line increases the vram size, you might want to customize it.
vmmouse.present = FALSE {- This disables the 'absolute' pointing device in the guest OS (as applications that require directinput relative mode needs to turn off 'relative' mode in the guest). Note: If you unset this option, you should also turn off the preference for motion ungrabbing in the settings dialog
Unfortunately not all aspects of 3D acceleration on the guest are actually accelerated -- Which are some of the following:
Parent
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The games I've seen VMware running myself... The sims, World of Warcraft, Half life and Second life.