I wrestled with this all day long. Hopefully this post will help people in my position.

Setup: I have a Windows Desktop and a Mac Laptop. There is plenty of space on the desktop so I do not own an external hard drive. I want to backup my laptop wirelessly using Time machine to a remote drive on my XP machine.

What I thought: I would need to have a separate partition formated HFS+ to use Time Machine. Most of the day was spent finding out that HFS+ and NTFS (Window’s File System) can not exist on the same drive. Don’t ask me why.

Why I thought this: Previously, when attempting to backup to a network drive, Time Machine gave me “The Backup Disk Image could not be mounted.” I automatically assumed Time Machine could not write to Windows.

Why I was wrong: Time Machine creates a “.Sparcebundle” and saves files there. Apparently this can be saved on NTFS. The problem I had was creating this Sparce bundle in the first place.

My Solution: Thanks to this site I was able to solve the issue. Here’s what I did.

1. Select the location for the remote backup. I chose the partition I created TimeMachine (T:).
2. If you have not enabled “Unsupported Network Volumes,” follow this tutorial.
3. Mount your network drive and select it in Time Machine.
4. Start Time Machine (Menu button > Backup Now) and watch your remote location.
5. A file is created with the structure ComputerName_MACAddress.tmp.sparcebundle. Copy this file name.
6. On your Mac, open Disk Utility. Click “New Image.” Use the following settings:
7. Save As ComputerName_MACAddress
8. Volume name can be whatever you want.
   ***EDIT: Custom volume size must be the last value set***
9. Change partition to “No Partition Map”
10. Change Image Format to “Sparce Bundle Disk Image”
11. Custom Volume size. Set the maximum you want to use on your remote location. Don’t worry if you don’t have the room on your Mac.
12. Save. Move this file to your remote location.
13. Tell Time Machine to backup again and it should be working.

Good luck! If you found this article helpful, visit my sponsors.

Hopefully the rest of my computer upgrade won’t warrant a blog post!

Long overdue edit (1/30/2010): Thanks to everyone who has commented! It’s so great this article is being found and is helpful. If you’re trying to get this to work, there are some very helpful comments. In particular, Chris points out these three points:

1. The MAC address has to be the ETHERNET adapter’s MAC Address and “not” the Airport’s MAC address.
2. The final file you copy will be in this format: ComputerName_MACAddress.sparcebundle
3. .sparcebundle is added to the file name by the Disk Utility, not you and does not need to be removed.”

Also, my desktop computer has been busted for over a year now. I’ve been running for luck not backing up my macbook and using it as my one and only computer. Sorry I didn’t do my job in keeping up with this post.

Thanks for reading and good luck!

Jason

ps: If you found this helpful, please visit a sponsor.