What version of OS X does the app support ?

The app should work on 10.8 or newer.

Are backups made by the Windows version of Backup TA compatible with the Mac one ?

YES, although only backups made with v9.8 or newer were tested.

Are backups made by the Mac version of Backup TA compatible with the Windows one ?

YES, although only Backup TA v9.10 was tested.

What devices are supported ?

Currently the app has only been tested on the Sony Xperia Z1, but should work for others too. You can see here a list of all the compatible devices with the Windows version of TA Backup. If your device is not listed, you can still try doing a backup and report if it worked.

Is root required ?

YES ! The app will alert you if your device is not rooted.

Can I use someone else's backup ?

ABSOLUTELY NOT ! Doing this will surely hard-brick your device.

Does it restore my DRM keys when I already unlocked the bootloader ?

Only if you made a backup BEFORE unlocking it.

Can I restore my TA while running a ROM with a custom (non-stock) kernel ?

Yes, but this will soft-brick your device and you need Sony PC Companion (PCC) or Flashtool to fix it by flashing stock firmware. It would be best to first return to a complete stock ROM or at least flash a stock kernel (do not confuse with stock based kernel !) before restoring the TA, this prevents the soft-brick.

Will a restore relock the bootloader ?

Maybe, if you made the backup when the bootloader was unlocked. Then it will relock the bootloader like it was never unlocked. Make sure you are on a stock kernel when doing so or you will end up with a soft-brick (see previous question).

What is 'Test restore (dry-run)' ?

This will simulate a restore but not actually perform it, thus leaving the TA partition unchanged. However, all the integrity and safety check will be performed. This is useful if you want to test if a backup is valid.

What is the correct file size for a backup ?

The TA partition size can differ per model, so there is no one answer to this question. Also the TA partition contains a logging area which changes and thus can be different in size each time the device boots, which can lead to different compression size of the backup file. You can rest assured that your backup is fine, also in file size, when the tool says the backup was successful.

HELP ! I got an error while trying to backup/restore !

The app logs a lot of debug information which will be useful to pinpoint the exact cause of the error. Open the app and go to the Help menu and select Open logs folder. You can make an archive with all the logs in that folder and send it (via an issue).