In a storage system, such as a storage area network, a snapshot volume or one or more checkpoint volumes are formed from the same base volume using a single repository containing multiple images of data stored in the base volume. The first image is started with the formation of the snapshot volume or the first checkpoint volume and is filled with blocks of data copied from the base volume, thereby increasing in size within the repository, until the first image is stopped and the next image is started. The next image is then filled with blocks of data copied from the base volume until stopped. Thus, the blocks of data are copied only into the most recently created image within the repository. With the creation of each checkpoint volume, a new image is concurrently started in the same repository. Each checkpoint volume is dependent on the image that was created concurrently plus any images created thereafter.