Archived - MobileMe: Computer has less free disk space after turning on iDisk Syncing
After turning on iDisk Syncing, you may notice that your computer has less available disk space.
This is normal; no troubleshooting is necessary.
iDisk Syncing in Mac OS X 10.3 and later creates a disk image of your iDisk locally (meaning, it keeps a copy of your iDisk on your computer). This image takes up space on your hard drive.
Mac OS X 10.5 and later
The amount of space used depends on the amount of data that is in the folders of your iDisk that are synced (Backup, Web, Library, Groups, Shared, and Library are not synced). For example, if you have 5 GB of files in your Documents folder on your iDisk, after turning on iDisk Syncing, your computer's free hard drive space will decrease by approximately 5 GB.
Note: You may see a minor difference between the total size of your iDisk and when viewing them between Mac OS X v10.6 and v10.5. This is due to improvements in how disk space is displayed in Mac OS X v10.6 Snow Leopard.
Mac OS X 10.3 and 10.4
The amount of space used depends on the total size of your iDisk (not on the amount of space used). Images are approximately 25% larger than the total capacity of your iDisk. For example, if you have a 10 GB iDisk, after turning on iDisk Syncing, your computer's free hard drive space decreases by approximately 12 GB. If you want iDisk syncing to use less space on your computer, you will need to make your iDisk smaller by adjusting storage settings.
Note: For Mac OS X 10.3 users, iDisk Syncing only works with iDisks up to 2 GB in size.