iPhone mobile device with firmware OS version 2.0 (including iPhone 3G) will make a full image backup of the iPhone device with all installed applications, instead of just documents and library data to computer (Mac or PC) during the synchronization process, each and every time when there is a change to the installed apps and games. The backup of complete snapshot of iPhone apps can take a while to complete, especially for iPhone device with many apps loaded, causing significant slow down of sync process.

The backup is important for restoring purpose when iPhone is corrupted or the operating system goes wrong. However, for users who don’t require the backup (meaning that if something bad happens on iPhone, all data, programs and games is considered lost), or have other way of performing the backup rather than through iTunes syncing (such as over-the-air OTA or third party software utility), it’s possible to disable the backup process during iPhone (3G)-iTunes sync process.

Previously, iPhone users have to manually cancel the backup in iTunes when iPhone backup process is in progress to skip and bypass the slow backing up of iPhone, but terminating the backup process halfway may result in corrupted backup, which will cause corrupted phone when accidentally used to restore to iPhone. The workaround is to use the following hack to force iTunes to disable backup process and skip backing up the complete iPhone image.

  1. Quit iTunes.
  2. Open Terminal.app.
  3. Type (or copy and paste) the following command, and then hit Return:

    defaults write com.apple.iTunes DeviceBackupsDisabled -bool true

  4. Open and run iTunes.
  5. Plug in and connect iPhone 3G or original classic iPhone on version 2.0 OS to computer for syncing. The backup process should be bypassed and skipped now, and only music or podcasts are synced.

The command above changes a hidden setting in the iTunes preferences to disable and turn off the backup process. To re-enable or turn on and run the backup of iPhone again, just issue the following command:

defaults write com.apple.iTunes DeviceBackupsDisabled -bool false