Backup works by copying files and data from the phone to the PC. Restore works by copying the files and data in the other direction. The backup and restore operations rely on being able to copy files when they need to. If a file is locked then it cannot be copied. In normal phone use, a range of servers and applications will have files open for reading or writing and may have updates pending on some files. Files in the public area of the filing system can be backed up and restored directly by the PC Connectivity subsystem but this requires all other processes to free up file locks when required. Platform security (introduced in Symbian OS v9), and specifically data caging, provides for ownership of private data files (see Section 2.2). Ownership of public data files is more complex.

• A backup operation needs to read files so processes must relinquish exclusive-locks on files but can retain read-locks (although in practice many processes just relinquish all locks for the sake of safety and simplicity). In order for a backup operation to take place, applications and servers must flush any pending updates to files and allow all files to be read (but cached data can be retained as backup will not alter data files). When the backup has taken place, servers and applications can re-take file locks and carry on.
• A restore operation requires exclusive access to files so processes must relinquish all locks on files. In order for a restore operation to take place, applications and servers must discard all cached data and allow files to be written or overwritten. When the restore has taken place, servers and applications must reload their data from files that can be expected to have changed.

What you should do as a developer If you are amenable for an appliance that owns abstracts again apprehend through the afterward steps:
1. Familiarize yourself with the advancement and restore concepts so that you can again accomplish the appropriate decisions apropos the advancement and restore of your appliance and its data.
2. Decide what apparatus will be appropriate in adjustment for your appliance to become advancement aware
3. Decide which abstracts needs to be backed up and adequate and how it should be dealt with. This will crave the afterward decisions to be made, a. Decide whether or not you accept accessible or clandestine abstracts that needs to be backed up. b. Decide how you will acknowledge to advancement and restore operations (i.e. do you charge alive or acquiescent advancement and restore). c. If you charge to apparatus alive advancement again do so. d. Decide whether or not you ambition to accept your arrangement files backed up.
4. Produce a advancement allotment book that covers the decisions fabricated above.