If there’s one thing you can admire backup specialists Dantz for it has to be persistence. Go back a few years and its Retrospect product range included an Express version which only supported media such as CD/DVD and external hard disks and was offered as a budget priced backup solution for single users and had no tape drive support. Move on quickly to v5.6 and the Express option was suddenly abandoned to be replaced by Retrospect Professional which targeted home and very small businesses, was licensed to back up one local and two non-server remote systems and also included support for tape drives. We've reviewed Retrospect 6.5 previously. Fast forward to the present day and Dantz now introduces Retrospect Disk-to-Disk for Windows (RDDW) – a product that backs up to CD/DVD and external hard disks but has no tape drive support.

Dantz reasoning for resurrecting this version of its backup software is that hard disks now offer a sufficiently high capacity to handle server and workstation backup and USB 2.0 and FireWire equipped external models are fast enough to compete against tape as a removable media suitable for off-site storage. RDDW supports a single Windows server and also supports Dantz’ optional add-ons which include agents for securing SQL Server and Exchange Server and a disaster recovery tool. Remote workstations can also be included in the backup scheme but no clients are included in the base products. Installation is a simple affair and you’ll find Dantz has redesigned the main interface making it even easier to use. Retrospect takes a different approach to conventional backup software as it doesn’t use a file’s archive bit to determine whether it needs to be secured. Instead, it compares the files it has already copied with those on the hard disk and, if a file already exists on the backup media, it will not be copied again. A new backup wizard makes life easier and Dantz has added a job monitor that allows you to view all jobs whether active, scheduled or waiting along with history and alert logs.

As another hard disk-based option, NAS appliances are also supported but backup options are more limited as RDDW doesn’t support NDMP (network data management protocol) and can only access remote systems if the client is installed first. This means you can only back up from NAS appliances that are Windows 2000 Server-powered and can be accessed via Terminal Services or Remote Desktop. Although not documented at the time of writing we see no reason why Microsoft’s new Windows Storage Server 2003 shouldn’t work with RDDW although bear in mind that to support the Volume Shadow Copy service you’ll also need the optional open file backup agent. It’s far easier to treat a NAS appliance as a backup destination as Retrospect sees it the same as any other network volume.

There’s no denying Dantz’ logic in using hard disks as a backup medium as capacities have increased as prices have dropped. It’s also true that tape drives represent a comparatively high outlay with many high-speed drives costing more than the servers they are supposed to be protecting. However, from our own experiences we are not comfortable recommending using removable hard disks as off-site storage and in media rotation schemes. For example, we used an external USB 2.0 hard disk to secure data from one system and synchronize it with a PC in a remote location on a daily basis. For six months this worked fine until the 250GB hard disk decided it had had enough of being frequently on the move and packed up. Furthermore, the constant plugging and unplugging of the unit took its toll on the USB socket which gradually worked loose and eventually failed to function. Quite simply, tape is designed to be portable - the cartridge design is more rugged and environmental tolerances are higher than hard disks making it a far safer choice for off-site storage as part of a backup strategy.

RDDW is undoubtedly a very easy backup product to get on with and we have always found it simple to use with plenty of features for keeping track of your data. However, we aren’t convinced of the wisdom of using hard disks for off-site storage as these devices were never designed for this purpose.


The backup argument is always heated and the debate on which is the best backup medium will continue to rage. Initial outlay for hard disks is much lower than for tape drives but, conversely, storage costs are much higher. Dantz is convinced that the external hard disk is the ideal backup medium but our experiences suggest that it isn’t.