Mac OS X v10.5 (Leopard) introduced the concept of sparse-bundle disk images, where the data is stored as a collection of small, fixed-size band-files instead of as a single monolithic file. This allows for more efficient backups of the disk image, as only the changed bands need to be stored.

One common source of sparse-bundles is Mac OS' backup utility, Time Machine, which stores the backup data within a sparse-bundle image on the chosen backup volume.

This software package implements a FUSE virtual filesystem for read-only access to the sparse-bundle, as if it was a single monolithic image.

Installation

Clone the project from GitHub:

git clone git://github.com/torarnv/sparsebundlefs.git

Or download the latest tar-ball:

curl -L https://github.com/torarnv/sparsebundlefs/tarball/master | tar xvz

Install dependencies:

OSXFUSE on Mac OS X
apt get install libfuse-dev libfuse2 fuse-utils on Debian-based GNU/Linux distros
Or install the latest FUSE manually from source

Compile:

make

Note: If your FUSE installation is in a non-default location you may have to export PKG_CONFIG_PATH before compiling.

Usage

To mount a .sparsebundle disk image, execute the following command:

sparsebundlefs [-o options] sparsebundle mountpoint

For example:

sparsebundlefs ~/MyDiskImage.sparsebundle /tmp/my-disk-image

This will give you a directory at the mount point with a single sparsebundle.dmg file.

You may then proceed to mount the .dmg file using regular means, eg.:

mount -o loop -t hfsplus /tmp/my-disk-image/sparsebundle.dmg /mnt/my-disk

This will give you read-only access to the content of the sparse-bundle disk image.

Reading Time Machine backups

Time Machine builds on a feature of the HFS+ filesystem called directory hard-links. This allows multiple snapshots of the backup set to reference the same data, without having to maintain hard-links for every file in the backup set.

Unfortunately this feature is not yet part of mount.hfsplus, so when navigating the mounted Time Machine image these directory hard-links will show up as empty files instead of directories. The real data still lives inside a directory named .HFS+ Private Directory Data\r at the root of the volume, but making the connection from a a zero-sized file to its corresponding directory inside the secret data location is a bit cumbersome.

Luckily there's another FUSE filesystem available, tmfs, which will allow you to re-mount an existing HFS+ volume and then navigate it as if the directory hard-links were regular directories. The syntax is similar to sparsebundlefs:

tmfs /mnt/tm-hfs-image /mnt/tm-root

License

This software is licensed under the BSD two-clause "simplified" license.