This means that the existing system will continue to work exactly as it did before whilst using the old hard disk (but with more disk space now available or a faster SSD drive now in-place to help improve overall system performance). For example, when adding a new larger or faster hard disk or SSD drive to an existing PC, the entire contents of the existing drive can be copied over to this new disk and kept exactly as they were beforehand. Such disk cloning software is especially useful when adding new or upgraded hard disks or SSD drives to an existing PC.