Mac OS X Time Machine functions to restore your lost data whenever you need to. The tool typically creates periodic backup of your entire system and maintains an up-to-date copy of your important files to the Mac system itself or to an external hard drive, whichever configured. But if this backup image refuses to be accessed, you need an alternative solution to Recover Mac Data. The Snow Leopard Time Machine is incompatibile with an AirPort Extreme disk, iDisk, Windows formatted disk, and any network server that uses other than Apple File Protocol (AFP) file sharing. For this reason, a Snow Leopard user may observe its Time Machine backup failing at the time of restoration.

To elaborate such problems, suppose you create a Time Machine backup on an external disk connected to your Snow Leopard running computer. Some of your important file(s) get deleted or you observe a data loss situation. When you try to access the backup, it gives an error ‘109′ that further suggests that the disk image cannot be accessed.

Cause

The error ‘109′ usually occurs when the user creates backup via the network or the external disk is connected to AirPort Extreme that are not compatibile with Time Machine in Snow Leopard. Though  AirPort Extreme may seem to work as a Time Machine solution, but it is not supported.

The network server must use AFP file sharing and both of the computers (root and networked) should be installed with Mac OS X 10.5.6 or later to work with Time Machine.

Solution

You can replace the the AirPort Extreme disk with that of Time Capsule. In some cases, the following workarounds can also compel the AirPort Extreme disk to work:

Try to rename the AirPort  computer and  Time Machine drive to a small and an un-complex name.

Uncheck the option that is associated to backup data at lower battery power in laptops

Make a new network location to add Time Machine device network interface only to it

However, if you lose the data when no good Time Machine backup is available, use a Mac Recovery software. These are specific tool to scan the affected Mac disk and Recover Mac Data lost due to accidental deletion, operating system crash, and similar instances.

Stellar Phoenix Macintosh Data Recovery is an advanced and safe utility that recovers lost data for Snow Leopard (Mac OS X 10.6), Leopard (Mac OS X 10.5), Tiger (Mac OS X 10.4), and Panther (Mac OS X 10.3.9). The software uses powerful set of scanning algorithms and restores the lost data at a user-defined or default location.