Windows 7 to add native support for Virtual Hard Disks

Out of what little we know of the next version of Windows, this feature might just be the most interesting yet. A team at Microsoft is hiring developers to work on adding native support in Windows 7 for Virtual Hard Disks (VHD)Microsoft’s semi-proprietary specification for single-file virtual machine hard disks. Their job posting reads,

Do you want to join the team that is bringing virtualization into the mainstream? In Windows 7, our team will be responsible for creating, mounting, performing I/O on, and dismounting VHDs (virtual hard disks) natively. Imagine being able to mount a VHD on any Windows machine, do some offline servicing and then boot from that same VHD. Or perhaps, taking an existing VHD you currently use within Virtual Server and boost performance by booting natively from it.

Do you want to have the opportunity to work on a great Core OS team at the heart of Windows? If you have big ideas and want to implement them, if you love writing code, if you love delving into operating system internals, if you want to work on high visibility projects with direct consumer and customer impact and still work in a very technical environment, then you will feel right at home in this team.

Virtualization technology has been a great success with Virtual Server and Hyper-V. With native OS support on the horizon it will become an even greater hit. Our team is making this a reality in Windows 7. Consider the simplicity of backup using a VHD, or the portability of a virtual disk backed by a single file. These are a few reasons why this technology is poised to be one of the greatest features in Windows 7–come help us achieve this goal.

Whilst “one of the great features in Windows 7″ might be a bit much, this is right up there with the new multi-line Calculator. No seriously, this has rather interesting implications for IT administrators and even home users.

For example, having an VHD dedicated to gaming with optimized system configurations is entirely feasible then. A dynamic VHD would mean it would only take up as much room as it needs, you could move the file on many system and have the same experience, but best of all, you can still enjoy the maximum native performance at the same time being able to load it as a virtual machine to maintain and configure without rebooting.

Considering how much we don’t know about Windows 7, this is extremely promising.

Update: A few people I’ve talked to have expressed their concern this may not make it to RTM and I think it’s a valid point at any time feature may be cut so I’ll just add that note for everyone else.

Update 2: Apparently the technology already exists in Windows 7 today, as indicated somewhat below.

81 insightful thoughts

  1. @GBytes: You’re getting the wrong idea. This is not virtual disk image support (ISO/BIN) for CDs or DVDs, this is virtual hard disk. An entire hard disk with partitions, operating system and files can be saved as a single file.

  2. While I can see some practical uses for IT and system tinkerers, I think the best use would be a virtualized 32 bit environment on a dynamic VHD. As we know, there are some very big obstacles towards going full 64 bit, and this could very possibly be a way around that. No doubt MS wants to go 64 bit.

  3. Yes, VHD is just an exact image of the the data on your disk; it preserves the layout and structure as well. It’s a Microsoft implementation that is proprietary but made available under the Open Spec. Promise.

    I would like to think that they’ll use it for compatibility (legacy support) in 7, but I’m just guessing. They could take XP & Vista’s compatibility mode further by dropping legacy APIs etc wherever possible from 7 itself. They could then make VHDs available to customers that provide all the bare essentials to run XP, Vista programs. If they implement a virtualization layer for 7 by default, the use of the VHD might even be transparent to the end-user. This would be a different & interesting way to do legacy support, instead of using emulation, compatibility libraries or full virtual machines. Just a guess. (I think Vista Ultimate includes a stripped-down Virtual PC component, doesn’t it? And Hyper-V is/will be added to Server 2008? yes?)

    I was wondering though, if the WIM format might be better suited here?

  4. @T Man:

    Windows is already 64-bit & supports running 32-bit apps side-by-side via WOW64. It’s just apps/drivers that require low-level access that must be 64-bit. I think MS hasn’t marketed this well enough. Also, on more than one occasion, MS itself seems to not support 64-bit in some of their apps, for no particular reason. I remember recently Rafael Rivera showing how arbitrary the lack of 64-bit support in one of their apps was.

    Back-up is one possible usage scenario, though I still think WIM is the better format here (ignore my question about WIM in my previous post please)

  5. I think I need to change the default VHDL files’ extension!
    All the IDE save this kind of file with *.vhd, Windows 7 will think those file are virtual hard drive instead of devices’ hardware definition. :D

  6. They’ll probably remove the “create” and “edit” capabilities and make it like VMware player. Other Vmware will sue them or complain to the EU. (See Microsoft’s recent fear of the EU in the ODF case). Also, although different from virtualization, native ISO A-Z operations (mount, extract, edit, save, burn) is way overdue.

  7. I would imagine there’s a possibility Windows 7 may be a native VM running in a hyper-visor. It could solve a lot of problems and would make a lot of sense when you think about the current trend for VDI and blade desktops. It would for example give you the option of using a server to host a number of full desktops, and presumably move those desktops between servers, blade desktops or standard PC’s.

    Tom

  8. One consideration for an application of this technology, is in a complete hardware failure, one could take a server 2008 backup (which is stored as a VHD) and boot your server back up using this feature on a windows 7 machine. If it is not included in 7, I would expect this functionality to come into play with the next server release.

  9. Question is, who uses VHDs anyways? VMDK has now become a standard for virtual HDDs.

    On one hand, if it means I can boot from a (local?) VHD on my real system and use it like a real HDD with negligible performance hit…. woah

    On the other hand, I don’t trust Microsoft with Virtualization. I mean, It’s been 5? years since Microsoft bought Virtual PC from Connectix, and since then I’ve seen NO major improvements, features wise. How hard is it to implement multi-level-switchable snapshots? How about better support fot *nix guests? What about raw disk access? 3D Acceleration?

  10. I so hope this makes it, a lot of persons requested it during the Longhorn client beta. So it is most likely. The feature it guarantees is the ability to boot your installation of Windows 7 on any computer (possibly only Windows 7 PCs) I assume, but then again the ability to have access to your “computer”, all your files, all your applications and settings would definitely be cool. By the time Windows 7 hits market (around 2010 I bet), most external drives will be 2 to 3 TBs standard. Complete PC Backup in Vista (Ultimate, Enterprise and Business) backup in .VHD format, I think the ability to mount that same VHD on any computer running Windows 7 would make me upgrade to this release on all my computers in a heart beat. What bothers me though is licensing, would Microsoft allow us to have an additional bootable copy of Windows in the .VHD format, since you could have your external drive while at the same time being able to boot it on another computer while still using the same computer from which it was backed up. Unless there is some validation to prevent you from running multiple copies of the system/license at the same time.

  11. Xed,

    I think you’ll find that VHDs will become much more commonplace as a result of Hyper-V being included in Windows Server 2008 – watch the volume go up incredibly. Including things in the OS for commodity cost tends to dull momentum of even well established competitors – we’ve seen this movie before.

    As for Microsoft being trusted with Virtual technologies, I think we’re early on the *real* deployment from Microsoft – I think Hyper-V is the first – Virtual PC and Virtual Server were the versions inherited from the Connectix buy (albeit enhanced a little). And I think MS will always want good *nix support – they much prefer you to run *nix hosts on Windows than in their own right. Embrace and extinguish anyone?

  12. Of course, you can actually do this today using VHDMount (Part of the Virtual Server install), and some registry hacks. This was working well for me in Vista 32-bit, but when I went to x64 it stopped. I’m not sure what they’re planning to do differently in Win7 that will require major engineering.

    This should be an Ultimate Extra, at the very least.

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  14. I’m confused. We, as testers, have been requested native ISO/BIN support for ages and they go work on native support for an image format that’s used by a product not many people use? What the hell?

  15. I agree with you on that one Rafael, but then again, .VHD has become even more important now especially from a usability point of view. If you are running Vista Ultimate, Enterprise or Business and backup such installations with Complete PC Backup, then the format needs to be more flexible in how it can be used with Windows. I think the idea of building on what was done in Vista will really make the format a valuable tool for end users. The ability to simply carry my computer anywhere with me through an external drive, mount and use it like I would be sitting in front of my computer at home is just an awesome thought. As for ISO vs VHD, I think its all about ubiquity here and if you were to compare who would have most usage I would place my bet on VHD.

  16. @Andre: Why would you put a VHD onto a removable disk when you could just put the contents of the VHD on the disk to begin with? I see very little value in stuffing everything into a single file…

  17. @ Rafael, I don’t want the contents alone, I want my applications, files, SKU of the OS and settings/preferences too. For example, say I have Windows 7 Business on my desktop PC in my Home Office, I have done a Complete PC Backup of that computer.

    When I visit your house or an Internet Cafe and I plug in my external hard disk into a Windows 7 powered PC, all I have to do is mount and use that VHD like I am at my home computer. I can make changes, save files and do all the things I would normally do if I was at my Windows 7 Business PC at home. When I go back home all I would have to do is either restore the VHD image back on my PC’s local hard drive or sync back changes.

    I also think it would be a great alternative for persons who do not have hi-speed Internet connections who cannot use Live Mesh. Unless I am misinterpreting the intentions of what the Windows Team would like to do with .VHDs in Windows 7. Mac OS X users have the ability to install OS X on an external drive and boot it on any Mac based system they please, I think its about time Windows users get a similar feature. Again, I am concerned about licensing conflicts this might cause and the possible attempt Microsoft might implement to require some form of validation every time you mount on a new computer.

  18. > When I visit your house or an Internet Cafe and I plug in my external hard disk into a Windows 7 powered PC

    …and wait until the new hardware (obviously that PC would have different HW configuration) is recognized, installed, then reboot… and then find out your PC keeps BSODing after bringing the disk back home due to driver hell :)

  19. @rożen
    Grow up and take your poor sense of humor else where.

    This is ingenius even by my high standards.

    And, as always, another great find by our blog-od.

  20. @Tom

    rożen has a point! How do you suppose your computer will perform after it has reconfigured itself numerous times from booting it in various hardware configurations? And how is a computer BIOS even going to know how to boot a vhd? It would need some special bootsrapper cd or similar in order to do so. And how are other OS’s (that don’t neccesarily support mounting vhd’s) gonna be able to copy files to or from the vhd? Don’t get me wrong, I like the idea, but it certainly won’t be good for use as a portable operating system. For that you use a virtual machine setup.

  21. What the technology giveth, the EULA taketh away.

    My guess is that the best features of this will be artificially crippled by licensing restrictions.

  22. @ Shane: I am sure thats why Microsoft is hiring someone to help resolve issues with latency/performance and configuration. I am sure there will be diagnostic tools built into Windows 7 like the new Health Center that will ensure that your External disk with the .VHD is functioning properly and will alert the user of a potential failure. Please note that I said Windows 7 PC’s only, there was no mention of support for previous versions of the OS including the fact I said that the VHD would be mounted first in an existing Windows 7 installation then booted from. Predicting that there will be a host EFI based PC’s is not guaranteed so I went with the most logical approach to doing it.

    Although it will be chore to mount in an existing installation then boot from it, its still worth the effort of having access to your entire computer this way.

  23. @Shayne

    Still using XP? Windows Vista does things far diffrently to that of any other previous Windows OS. Who knows how they’ll change everything drivers in the next Windows. As much as many would like to disagree, Vista is superior for example: If I get a virus on XP, I do not get the same virus on Vista. Secondly, If I remove my hard disk drive from my computer and place it in a computer with entirely different hardware, it boots, reconfigures drivers, and continues to function. (you’d think they’ll have taken this into account also) It’s called modern technology and please oh god, stop taking shots at Vista’s stability. Run it for a while on a decent PC and you’ll see what I mean and no I don’t want to hear your ‘story’ this post is about a future feature, not what crashes more often.

  24. @Tom and others, Windows Vista is a Home and Small Office OS… I know this because at the place I work (which is a college), we have Vista, Server 2008, and 100% compatible Vista computer. However, we are having serious issues with it. No, not stability, we are impressed with it., not a driver problem, it is that their is a lack of features that existed before that does not. Now I understand that some feature was removed because of security issues it posed, however many programs like printing management software and such needs those “holes” to perform what they do. So right now, we have all the IT computer with Vista SP1, however the student and teacher computer run XP. And we have a bunch of Vista’s in a closet. We are currently finding ways to make Vista work, however with the new core and the lack of documentation does not help. I believe that Windows 7 (the next windows or Vista SP2… only time will tell), will be good, specially that it seams more business oriented.

    I think that Microsoft shoot their foot in MANY bad managerial decisions and lack of research from the perspective of the average user (that sees Vistas as simply XP with a new skin) and the lack of support of Business. Which gave Vista a very bad start and bad press. I think that Vista Business Edition/Enterprise should have been more business oriented, then the other editions. An example of a system that could have been implemented in Vista Business, is a system that detects your hardware, and sees what it can disable.
    If your system is slow, then Windows Classic theme will be put, and the none used services will be disabled by default. To tell you the truth, I made Vista run perfectly smoothly on a Intel Pentium 3 at 800Mhz with 256MB of RAM. And yes it startup just as fast as XP (MAYBE a tiny bit slower, but nothing really significant to realize). Yes I had to battle myself for an hour or so as the computer was sooo incredibly slloow, until I manage to disable everything and have it up and running and smooth. (I basically disabled everything expect security features, networking, and Vista instant search) (so basically down to XP with instant search). The only thing I changed was the HDD, from a 60GB 512Kb Buffer IDE to a 160GB SATA-II 16MB of Buffer was used. I imagine if I had the old HDD I would have need to disable instant search as it would have been too much for the HDD.

    So is Vista good? it depends. On a desktop Home or Small Business, I must say this is the best Windows yet. Exceptional stability compared to previous Windows edition, best memory management of all Windows, and now can be classified of “proper” memory management compared to other OS’s of TODAY, does not slow down over time, easy / fast install, great new features (you just have to dig them to found out, and learn to use them, unlike Apple there is no nice Video tutorial on Vista new features (bad managerial decision?! maybe..).

    As for Vista and viruses, well you can have the same virus on XP on Vista, however most of them will just stick there and do nothing. The security side about viruses with Vista is that now a 8 year old kid can’t make virus, you actually need to know how to program and actually dig trow the security and find a flaw.

    Also, Microsoft failed to mention that Vista is not backward compatible. Unless you payed 2k for a custom build computer and REALLY thought of Vista back in early 2006, and you made sure that all the hardware that you get you know that it won’t be form companies that will say “screw old products, we give little to no support, you want proper drivers, buy new stuff”, then Vista 64-bit (32-bit Vista is a last minute thing from Microsoft, so I won’t even consider it) will run way better then XP in all aspects without exceptions. Else be prepared to see issues that everyone talks about on the internet, aka: slow file transfer form X to Y with Z, stability issue, slow, fails to work XYZ, WinME2, etc…). I personally perform the all the test that I heard about on the net, and I have no idea what they are talking about, I DO NOT see them (ok their is, that is a lie, but it is not as exaggerated as people say, as for file transfer even big ones like HD movie we talk about 1sec more than XP). You think that I do badly my test? Well join the oh so many people that tested my comp,

  25. I would like to also add, that if Windows 7 is out, I would expect that it will be Vista SP2 in reality, as by then people will buy new powerful computers, that will actually support Vista. Also it will have a new clean image, so people won’t start bashing on it, specially that no one will think that Microsoft with screw up a second time around specially in a row, that is if you believe they did with Vista. People will simply read those bad comments and go “Ya right it is your system, go back in your cave comp-386 dude” or something similar.

  26. @ Tom: The same viruses that attack XP also attack Vista, just that they are not as functional unless you have certain settings in place such as UAC on, installed and updated Antivirus and AntiSpyware utilities.

    @ GBytes: I am confused by a lot of what you said.
    Quote:
    “Now I understand that some feature was removed because of security issues it posed, however many programs like printing management software and such needs those “holes” to perform what they do. So right now, we have all the IT computer with Vista SP1, however the student and teacher computer run XP. And we have a bunch of Vista’s in a closet. We are currently finding ways to make Vista work, however with the new core and the lack of documentation does not help.”

    Well, you say your school is connected to a Windows Server 2008 domain, File and Print Management are core features built into Active Directory, just make sure that role is installed. The wealth of resources available for Vista online from the many websites dedicated to the OS and plethora of Microsoft Newsgroups, help is only a click away. A lot of what you are saying does not make sense.

    Quote:
    “I think that Vista Business Edition/Enterprise should have been more business oriented, then the other editions. An example of a system that could have been implemented in Vista Business, is a system that detects your hardware, and sees what it can disable.”

    Please understand that the user interface does not necessarily define whether its a business or consumer OS. What makes Windows Vista Business and Enterprise ‘business’ oriented operating systems or SKUs is the functionality built in: ability to join a domain, encryption, support for a specific amount of RAM (128 GBs in 64 bit platform), Group policy editor, Complete PC Backup, collaboration and small business tools.

    Windows Classic is just a theme in Vista, just like Luna was a Theme in XP.

    Quote:
    “Exceptional stability compared to previous Windows edition, best memory management of all Windows, and now can be classified of “proper” memory management compared to other OS’s of TODAY, does not slow down over time, easy / fast install, great new features (you just have to dig them to found out, and learn to use them, unlike Apple there is no nice Video tutorial on Vista new features (bad managerial decision?! maybe..).”

    Vista is not the first release of Windows to introduce pre-emptive multitasking and improved memory management. This has always been a hallmark of the NT line of operating systems. The reason why it does not slow down over time like XP its because the improved Defragmenter runs in the background as a low priority task keeping your system optimized. As for tutorial on new features in Vista, open Help and Support and type ‘Demos’ and you will see a lot of them introducing you to new features in the OS and a link to additional ones online. In fact, links to tutorials are there when you open Help and Support. I have used OS X extensively and I am not aware of any multimedia tutorials in the Help system, just static HTML information about new features and how to operate in the OS.

  27. @Andre Da Costa
    What tech-savvy life form uses UAC, Anti-virus or Firewall software/hardware. Come on…

    @GBytes
    Sorry, but I find it difficult to follow your train of thought although I think I may catch your drift and suggest you refrain from commenting on my own comments further before my head explodes from your overwhelming level of … . Anyway.

  28. @Tom: due to my past experiences I learned not to run my OS on different PCs. If that can be done in Seven or even in Vista with ABSOLUTELY no harm that’s great. FYI your attitude isn’t healthy either

  29. Nice scoop! Virtual Machining is a very important piece of the windows 7 puzzle which Microsoft will need to hash out over the new few years in order to make Windows 7 successful.

    If Windows 7 can seamlessly run old applications through some virtualized compatibility layer, it will be a huge plus for successful uptake.

    Another thing they need to work on is driver handling. New-drivers-for-every-new-OS is a relic of the past. I should be able to plug old hardware in and run it at a minimal level with old drivers (even if in some kind of contained/virtualized environment).

    And finally, Virtualization needs to support DirectX. Imagine the leverage this OS would have if it can play all the great old 3d games in a virtualized-but-seamless XP enviroment.

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