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Maintain a drive

Backing up and restoring a drive

Save a whole USB drive to one image file from your phone, as .img.gz or a plain .img, and write it back later. Free.

BootForge can save an entire USB drive to one file on your phone and write that file back to a drive later. Use it before you re-prepare a drive you’ve set up just the way you want, to keep a known-good copy of a rescue stick, or to put one drive’s contents onto another. It’s free.

Open Tools → Back up & restore with the drive connected. The screen names the target drive and has two directions, Back up and Restore.

Backing up

A backup copies the whole drive, partition table and boot areas included, not just the files you can see. Four switches decide how:

  • Compress the file — on by default. Saves as .img.gz, which BootForge restores directly. Turn it off for a plain .img that any desktop imaging tool reads.
  • Skip empty space — on by default. BootForge reads only the parts of the drive that hold data, which is much quicker on a mostly empty drive. It understands exFAT and FAT32 volumes; anything else is read in full. The saved file still restores the whole drive, and space that was empty comes back empty.
  • Keep going past bad sectors — off by default. If the drive refuses to read part of itself, that part is saved as zeros and the backup carries on instead of stopping. It’s for rescuing what you can from a failing drive: whatever couldn’t be read is not in the file, and the result says how much that was.
  • Check the file afterwards — on by default. Reads the saved file back and compares it with what the drive gave.

Tap Choose where to save, pick a place for the file, and the backup starts. It keeps running if you leave the screen, with progress in the notification shade. Keep the drive still: if it’s moved or unplugged, the backup stops.

A backup only reads the drive. Stopping one, or one failing, changes nothing on the drive. The partly written file just isn’t a usable backup.

When it finishes, the screen tells you which of three things happened: the file was read back and matches, checking was switched off, or the file couldn’t be read back and so wasn’t checked.

Two things worth knowing about the file:

  • With Skip empty space on, files that were deleted but not yet overwritten are not in it. The backup holds what the drive’s filesystem considers in use.
  • When the end of the drive is empty, the file can stop where the data stops. The result says so, and restoring that file leaves the rest of the target drive as it is.

A backup is a copy of the drive, not a check that the drive boots, and the phone can’t open the files inside it.

Restoring

Switch to Restore, tap Choose an image, and pick a backup, either .img.gz or plain .img. BootForge can’t check what an image file holds, and it tells you so: whatever is in it replaces the whole drive, byte for byte.

Skip empty space is on here too. The empty parts of the image aren’t written, which is far quicker, and the restored drive works the same. The catch is that the drive’s free space keeps whatever was on it before rather than being wiped. If you’re restoring onto a drive that will leave your hands, turn it off so every byte is written.

Restoring erases the drive, so it goes through the same confirmation as every other erase: the drive’s name and capacity, the image you picked, and a plain warning that it can’t be undone. As with a single-image write, the drive is read back afterwards to check what was written, and that check is on by default.

Afterwards the drive holds what the image held. Whether your phone can browse it depends on what that was; a PC reads it either way. To use the drive for storage again later, format it from Home.