iTunes keeps the iOS backup folder directly on the system drive. The space on your primary Windows partition – precious and often scarce – is constantly reduced with the ever-expanding iOS backup folder. Changing iTunes backup location is not a straight-forward task; however it is easy to do so as you follow the steps below.
Why relocate iTunes iOS backup folder to another drive?
iTunes backs up only certain iOS data such as app files, settings and camera roll photos from the iPhone, iPad, or iPod Touch each time you sync. Nevertheless, it is often unaccounted for how quickly the iOS backup files may accumulate on the system drive and take up valuable system resources ultimately leading to a less than ideal system performance. 
The guide below is for advanced users who would like to change only the iTunes backup location. If you’d like to free up even more space on your primary computer drive, you can change the location of the entire iTunes library by following this tutorial instead:
Transfer iTunes library to new drive
How to change iTunes backup folder location
To move the iOS backup folder to another drive, you need little more than an external hard drive or a second partition on your PC with plenty of space and a couple of in-built Windows tools.
If you are on Windows XP, please scroll down to Move iTunes backup folder under Windows XP
Locate your current iTunes backup folder. If you are using Windows 8, 7, or Vista, to locate the iTunes backup folder use the Windows Start Menu and enter the following in the Search box:
%APPDATA%\Apple Computer\MobileSyncMove the current iTunes iOS backup folder to the new desired destination via a simple drag and drop
NOTE: Make sure that you have the “Backup” folder fully copied to the new destination drive. Once you do so, you can either delete the “Backup” folder from the original location or rename it to “Backup_OLD”. At the end of this guide, you can delete the “Backup_OLD” folderAt the original folder location, press the SHIFT key, right-click and select “Open command window here”
This will open a command window adjusted for that folderIn the command prompt window, manually type in the following command where E:\ is the new drive location (drive letter may vary) and “Backup” is the name of the iOS backup folder you just moved:
mklink /J “%APPDATA%\Apple Computer\MobileSync\Backup” “E:\Backup”
Info: “mklink” is the Windows shell command for adding a symbolic link. The “/J” switch refers to a specific kind of symbolic link called directory junction. Refer to this article to learn more about symbolic links.
You will now see the command prompt window return a success in creating a junction A new folder shortcut called “Backup” will appear in the original location Double click on the “Backup” folder shortcut and while it may seem you are still within the MobileSync folder on the C: drive, what you actually see is the contents of the “Backup” folder you previously moved to the new location. You can think of it as a virtual tunnel created through your computer directory space That’s it. You have now learned how to move iOS backup folder from the primary partition to another drive and, in the process, freed up valuable system spaceMove iTunes backup folder under Windows XP
From the following Microsoft page, download the application named Junction to your PC Desktop:
http://technet.microsoft.com/en-us/sysinternals/bb896768.aspxExtract the file “junction.exe” from the ZIP folder to the Desktop
Locate the iTunes backup folder which can be found here: C:\Documents and Settings\YourUserName\Application Data\Apple Computer\Mobile Sync
Move the current iTunes iOS backup folder to the new desired destination via cut (CTRL + X) and paste (CTRL + V)
Run Command Prompt: Press the Windows logo key (in the lower left part of your keyboard) and hit the R key while you keep the Windows key down
In the newly-appearing “Run…” window, type in CMD and hit the Enter buttonNow type: cd desktop
NOTE: do not copy/paste in the command line window, as the commands will not be executed.
Now, create an NTFS junction point by typing in the following command: junction “C:\Documents and Settings\(USERNAME)\Application Data\Apple Computer\MobileSync\Backup” “E:\Backup”
Where E:\ is the new drive location (drive letter may vary) and “Backup” is the name of the iOS backup folder you just moved
NOTE: both the original and the destination hard drives must be formatted in NTFS and not in FAT32 in order for this to work.After the execution of the command, a new folder called “Backup” will appear at the original location. All the folder’s contents will, however, exist only on the destination drive.
This is how to move the iTunes backup folder from the original system drive to a new location under Windows XP.
