If you have:
a) a smallish C: drive (say, an SSD)
b) iTunes installed for iOS device backups
c) a need for always-with-you backup/restore via USB (on a laptop, for example)
then this article is for you! Admittedly might be best to put iTunes on some always-on PC, perhaps in a VM, to sync via WiFi. But not all folks are allowed to do that. And some folks can't use iCloud for iOS device backups either. An example would be an iPhone or iPad corporate policy/mandate, for example.
Well, I figure many such folks might be looking for a way to free up that precious C drive space, by moving those large iOS backups off C: to another drive (preferably encrypted).
You are not supported by Apple, or me, in any way by following these instructions.
The simple command appears harmless enough during my testing, and works quite nicely. You can see for yourself by watching the video I created. You will also see that despite my own system's iTunes install on my D: drive, the large (18GB) backups were still on my C: drive space, with a good dive into backups explained at Apple's site, About iOS backups.
It's not hard to do this, using the simple magic of the mklink command. Think symbolic link for NTFS. Nice work-around to a problem Apple hasn't yet solved!
Here's the basic steps I followed, on my Windows 8 64 bit system (same exact steps for Windows 7 64 bit):
1) Close iTunes
2) Move MobileSync to D:
You can drag and drop the MobileSync folder to your D: drive, for example:
3) Open a Command Prompt as Administrator
(in Windows 8, easiest to type Win+X, then select "Command Prompt (Admin)"
4) Issued the following command (replace username with your actual username)
mklink /J "C:\Users\_myusername_\AppData\Roaming\Apple Computer\MobileSync" d:\MobileSync
5) Issued the following single command to verify it worked
dir "C:\Users\_myusername_\AppData\Roaming\Apple Computer"
I could see the
<JUNCTION> indicating success, and found that subsequent iTunes backups behaved normally, seen in the walk-through video below.
Feb 22 2013 Update:
Thanks for feedback from Anonymous, I added quotes to syntax for consistency, added better descriptive text for myusername