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The old fashioned way


January 11, 2008 – 7:04pm Resize a Boot Camp Partition for Use with VMware Fusion

I’m sure this happened to a lot of us, but I started out with my Windows Boot Camp partition about 5GB. My only intention was to use it to test out our web sites in multiple windows browsers. However, after installing all of the Windows XP updates, service packs, VMware tools, multiple IEs, and Firefox, I only had about 400 MB of free space available. I finally hit the tipping point where to install new software (SPSS) I would need more space. No way did I want to go through starting from scratch. Downloading all of those windows updates took FOREVER. So, here is how I managed to resize the Boot Camp partition and still get it to work in Fusion. These steps were performed on a MacBook Pro running Leopard and a Windows XP Boot Camp partition formatted as FAT32.

  1. Step 1: Backup current windows partition. To do this I used Disk Utility and an external USB hard drive.
    • I had some free space on this external drive, so under Leopard’s Disk Utility I created a new partition at 6GB called “Windows Backup” (without losing any existing data on the drive!). I used the standard Mac OS Extended (Journaled) format.
    • Once the new partition is finished, select your existing windows drive in Disk Utility, select the “Restore” tab, then drag the existing windows drive from the desktop into the “Source” field. Then, drag the new “Windows Backup” partition on your backup drive over to the “Destination” field. Don’t check “Erase Destination Drive” as that might give you an error. If you want to make sure there are no files on the backup drive, you can use the Disk Utility to erase it by selecting that drive in the list of volumes on the left and then using the “Erase” tab.
    • Click “Restore” to start the backup of your current windows drive onto the backup volume.
  2. Once the backup is complete, run Boot Camp Assistant and use the option to restore you disk to a single Mac OS X Volume. Scary, I know, but remember you just backed up your Windows disk!
  3. Once the Windows partition has been zapped, run the Boot Camp Utility again and create a new Windows partition. Drag the partition slider to the new size (I chose 32 GB, let’s hope that’s enough this time!). Insert your Windows installation CD, and then hit Start Installation. Restart.
  4. Format the Boot Camp Partition in the Windows World.
    • When the Windows installer starts, Press Enter to continue, then F8 to agree.
    • The next screen is the file system format screen. Select “Format the partition using the FAT file system (Quick)”. You should use FAT in order to restore from the mac world because OS X can’t write to NTFS. After this is all over you can convert the file system to NTFS from within Windows later if you want.
    • Continue to format the partition as FAT32. Once this is complete, your computer will restart. Once it shuts off, as it’s booting up hold down option to boot back into Mac OS X. If you miss it and Windows is starting up, hold down the power button to turn the computer off and then power it back on holding the option key.
    • Source: here.
  5. Restore Windows!
    • Open the new Windows hard disk from the desktop. There will be some windows files in there… delete them all. Drag them to the trash and empty it. Some files may reportedly be lockec, but click OK to continue.
    • Now, locate your windows backup location that you used in the first step, and copy these files from the root level of the folder to the new Windows hard disk: ntldr, NTDETECT.COM, boot.ini, and PAGEFILE.SYS. To do this I had to use terminal because I couldn’t see these files from the finder. If you can’t see them either, open up the terminal (in Applications/Utilities) and us the “cp” command.
      cd /Volumes/Windows\ Backup/
      cp ntldr /Volumes/NO\ NAME/
      cp NTDETECT.COM /Volumes/NO\ NAME/
      cp boot.ini /Volumes/NO\ NAME/
      cp PAGEFILE.SYS /Volumes/NO\ NAME/

      Once those are copied (my PAGEFILE.SYS was HUGE by the way, so if terminal seems to be ignoring you just let it run…), select the remaining folders and files and copy them to the Windows hard disk.
      Reboot into your Windows partition. Goto Apple > Restart and then hold down option, or go into System Preferences and select the Startup Disk icon to select the windows partition (the new one!).

    • When windows starts up, let it run chkdsk, then let it restart itself back into Windows.
    • Once booted into Windows, I got a notice that I had to re-authorize my Windows Installation. This is a huge pain in the butt, so I said “Later…” and hoped it would go away when I started Windows from within fusion.
    • Restart, holding down option to boot back into Mac OS X.
  6. Now we need to get the new Boot Camp partition working with Fusion. For this I used the tips here.
    • Delete the VM config file (/Users/[username]/Library/Application Support/VMWare Fusion/Virtual Machines/Boot Camp/[your /dev/disk#]/Boot Camp partition)
    • Start up VMWare Fusion using “Boot Camp”. It will rebuild the VM file for you and then boot Windows. Hit cancel to avoid re-installing the VMWare tools (since they’re already installed).
    • Celebrate! Windows didn’t ask me to reauthorize my copy! Everything works great (hopefully) and you now have a 32GB Windows partition.

Hopefully this well help you along the way. If you run into any problems I probably won’t be of much help, but feel free to post here and hope others have solutions for you.

Posted by in  OS X

22 Responses to Resize a Boot Camp Partition for Use with VMware Fusion

  1. Pingback: Yet Another Blog from Luar » Resize Boot Camp partition without re-install everything

  2. Loren says:

    You can technically omit the copying (and backing up) of PAGEFILE.SYS, since it only represents the volatile (in memory) data when the machine is on– and it probably isn’t, if you’re repartitioning. It stores no data that would not be otherwise lost from turning your machine off anyway. And if the file is not there when Windows boots, it will just be re-created. So save yourself the trouble and don’t bother with that file.

  3. Loren says:

    Also, if you need more space on your harddrive, you can reduce the size of your pagefile.sys by reducing the Virtual Memory that Windows allocates for you. The image file can be considerably reduced in size if you have a lot of RAM devoted to the machine, and that can end up saving a few GB of data.

  4. amardi says:

    When I tried backing up my bootcamp partition up as you explained, I got an error “file name too long”. My bootcamp partition is about 30GB and I’ve allocated 40GB to my portable USB drive backup partition. I tried everything in terms of repairing the disk, using a FAT32 filesystem, and Mac OS Extended (Journaled). I tried googling for a solution but couldn’t find one. Does anyone know the answer?

  5. Toweri says:

    Amardi: The “file name too long” message you received is because Windows file system accepts 255 char long filenames – something Mac OS doesn’t tolerate.
    Make sure all your file names are 31 chars or less, and you’ll have no problem!

  6. DreadFree says:

    Great walk through!

    One little tip for those who are as “terminally” challenged as I am. If boot.ini and aren’t visible in Finder, you can enable the display of hidden files by typing the following command line into Terminal:

    defaults write AppleShowAllFiles TRUE
    killall Finder

  7. robro says:

    can anyone verify if this actually worked for you?

    also, on step 4, do I need my copy of the windows cd again? It’s not clear. It seems like I do, and then that I need to delete it all after installing it. why can’t i just use the disk utility to format it to fat32 instead of installing windows again to format it?

  8. Scott Meves says:

    Hi Robro: Yes, I used my Windows cd again in step 4. You create a new FAT partition so that when you boot back into your mac you can manage the copying of your backed up windows partition onto the larger partition you created in step 4.

  9. robro says:


    I see now why I need to do the whole windows install again. I just tried to copy my files without the cd thing (wanted to save time, and didn’t have the cd with me right now) so I just skipped that step. but b/c I did that, when I reboot w/ the option key held down, I the bootcamp partition doesn’t show. I think doing the install w/ the cd somehow creates that option for you in the beginning.

    anyways, will try again when I have my cd with me.

    thank you for the prompt reply.

  10. robro says:

    sorry, but another ques. on step 4, did you fully go through the windows install, or did you just stop it after the format to FAT?

    also, is it FAT or FAT32 that you formatted to on that step?

  11. Scott Meves says:

    Hi Robro: it’s FAT32. After the windows installer is done with making the partition, it will reboot to try to continue the windows installation onto your shiny new empty partion. As it’s booting (after the partition but before it begins the windows installation) up hold down the option key to boot back into Mac OS X. If you miss it and Windows is starting up, hold down the power button to turn the computer off and then power it back on holding the option key.

  12. theFATangel says:

    I was trying to find a way to have a Windows install not take up so much space of my MacBook Pro’s internal drive. I tried various methods of getting Windows to boot off of a USB volume but as it turns out Apple’s firmware does not support this (it is a long and un-fulfilling hack that pretty much doesn’t work unless you have an older model MacBook anyway).
    In my obsessive preoccupation with trying to get this to work, I discovered a nifty free program called MojoPac Freedom. It allows you to do the next best thing. Basically you can create a virtual windows installion on an external USB drive based off your own native installation. This virtual installation runs at native speeds and “borrows” your native install’s system files to run the virtual environment. This is not virtualization in the VMWare sense. Any programs you install in MojoPac are installed on the external USB drive leaving your native/internal XP installation pristine and slim. The best part is once you’ve created your MojoPac drive, you can take the drive to any other Windows XP machine and run your virtual profile on that machine. Its actually pretty cool. Some caveats: not all software works well with MojoPac, especially those that install their own drivers.
    For example I reduced my 21GB Windows XP BootCamp install to 8GB (leaving space for future updates etc.) without any software other than antivirus/spam utilities and windows software. I then launched my MojoPac USB drive profile and installed Steam and then the Portal game (>7GB) on it. I can now play my game when I need to without having to use up so much of the precious internal drive on my MacBook Pro for my Windows installation. The best part is you can try it out and if it doesn’t work for you you can reclaim the HD space and your native Windows install will be as pristine as before you tried out the MojoPac. Plus, I can bring my USB drive to a friends house and use his XP install to boot my same MojoPac profile and play the game on his rig.

  13. Siva says:

    According to following article looks like it might be more easier to backup and restore using WinClone.

    Looks like it is a simple as below.

    1. Create an image of BootCamp using WinClone
    2. Delete and re-create (with the required size greater than or equal to previous size) BootCamp partition using Boot Camp Assistant.
    3. Start the Windows installation, and get past where you’ve formatted the C: drive as NTFS.
    4. Reboot into Mac and resotre the image created in step-1 using WinClone.

    Haven’t personally tried. Planning to do it soon.

  14. robro says:


    i followed your directions to the ‘t’ but I get a ‘non system disk error, press any key to restart’ error message when I try to boot into the windows partition…

    any idea on why this may be happening?

    thank you.

  15. robro says:


    Just wanted to report in that I got this working! apparently, the problem was that upon selecting the partition to install xp on, I only had a choice for NTFS for some reason.

    after some googling, etc, I found that it may have been the xp disc itself. apprarently, some of them don’t work on the install well for some reason. the solution is to burn the xp pro cd into a iso and then burn it back onto a blank cd. when I tried installing with that new copy of the xp cd, then I saw the options to format to fat.

    then I followed the rest of the directions, and it worked fine.

    thank you.

    btw, here’s the link on creating an iso image and burning it back:

  16. Scott Meves says:

    @robro — Thanks for the update. What a strange problem to encounter. I’m glad you found a fix!!

  17. robro says:

    yeah, one of those dumb windows vs mac things. I wish I didn’t have to deal with windows on my mac, but I have to for my work vpn…

    thx for the info on this site btw.

  18. Malachi Rothschild says:

    I followed the instructions pretty much to the letter. The only thing I did differently is use RBrowser instead of terminal to view and move the hidden files. I’ve used it for that before without any complications. When I tried to start up windows I got a disk error. Does anyone have any ideas about what might have caused that and how I might be able to fix the problem? I’m using 10.5.4.

  19. Malachi Rothschild says:

    Gah I think I just didn’t format the partition properly.

  20. Lenster says:

    I have followed the winclone route, trashed the vmware bootcamp files from the lib and restarted the bootcamp option in vmware. I can get the system to boot into safe mode but for some reason i get a black screen when starting normally?

    any ideas ?

  21. Lenster says:

    Sorry forgot to say that re booting in bootcamp only works fine so defo something to do with vmware me thinks …. got a deadline approaching for my Masters Dissertation and this happens !! almost tempted to go and buy word for mac. .. help me please…

  22. David says:

    The article reads: “Once the backup is complete, run Boot Camp Assistant and use the option to restore you disk to a single Mac OS X Volume”.

    I want to now: How long it takes to complete the restoration? It’s a 120 MB hard disk Macbook with Leopard. I tried to do this a whole 8 hours and i had to stop the process, because it didn’t happen to do anything.

    Thank you in advance for any help you could provide.