Buffalo have launched two new products to their range of external hard disk systems. The DriveStation™ Duo and the DriveStation™ Quad. As the names suggest these devices take either two or four hard disks respectively and are capable of various RAID configurations and high data transfer rates across a USB 3.0 interface.

I'm a great fan of external hard drives for backing up valuable data. Backups have always been important, as anyone that has failed to store data safely only to suffer a hard disk failure knows only too well. Hard-drive capacity has continued to outstrip every other storage mechanism to the point where the only practical way to back up your data is to another hard disk. With drive capacities now reaching the 3Tbyte level even dual layer Blu-Ray disks (50G capacity) will take 20 disks per 1TB.

Hard-disks provide the capacity, but there's another problem. You need to get your data from your main disk to your backup system. Most computers come equipped with general purpose USB 2.0 interfaces these days, providing a transfer rate of around 40Mbytes/second. Put another way that's about 4.5 hours per 1TB. OK at the moment you've probably not accumulated that much data - but you see the problem!

One way to improve performance is to use an eSATA interface - or 'external SATA'. This is simply a way of connecting an external drive directly to your computers internal disk controller. Much like an edge-connector of old (OK I'm showing my age!) connected peripherals directly to the CPU bus. This provides transfer rates of up to 400Mbytes/second - an order of magnitude better than USB. There's actually no need to go faster than this because it's also the speed you can suck data off your internal drive.

While eSATA is an excellent solution and works well for desktops, it's yet another port, yet another hole to fit into an already tightly packed laptop. USB 3.0 provides an alternative that, a little over 2 years after the specification was completed, is now starting to be seen on new computers. USB 3.0 is backwards compatible with USB 2.0, and so existing peripherals should work fine, but in it's new SuperSpeed mode can achieve an effective throughput of around 400MBytes/second - comparable with eSATA.

So now you have a backup media (hard disks) with the capacity and a transfer medium (USB3.0) to make backups practical. Unfortunately there's a chance that your backup hard disk fails and you may not notice until you need your data. Multi-drive solutions like the Buffalo DriveStation Duo and Quad answer this need through multiple drives running RAID (Redundant Array of Inexpensive Disks) configurations. A two disk configuration is the minimum you need, and hence the Duo. This will copy your data onto both disks automatically - should one disk fail you have the other and your can replace the failed drive with another and the system will automatically mirror the data to that new drive.

While two drives are good and provide redundancy it is somewhat wasteful. For every byte you want to backup you need to pay for two bytes of backup space. This is OK for most people but where the amount of data you want to manage grows even higher then this penalty is expensive. The four drive solution allows more efficient storage of data - instead of making multiple copies of your data the system will spread data across all disks such that if one fails there is always enough on the remaining drives to recover your data. RAID5 for example only reduces capacity of a 4 drive system by 1/4 to store redundancy data.