Drobo, or Data robot, is external storage re-invented for PCs and small office: home office (SOHO) servers.

Drobo's core technology inventor is Geoff Barrall, a co-founder of the company, and also the founder of Blue Arc which currently supplies some of the world's fastest and most scalable hardware-accelerated, network-attached storage (NAS). Barrall sold his holding and interest in BlueArc some time ago, and has now come up with Drobo.

There's no actual mechanical robotics involved at all though. What we have is a mainboard in a small toaster-size black box. This contains an application-specific integrated circuit (ASIC), firmware, a buffer, four e-SATA ports for four 3.5-inch disk drive slots, and a USB 2.0 port to connect to a PC, Windows or Mac, or server host.

There is no FireWire support and this may well not happen at all if faster USB comes along. Neither is there any Ethernet support. We might speculate that this could happen if Drobo expands its market into the small and medium enterprise (SME) area.

Drobo in use

The drive slots can take any capacity 3.5-inch form factor SATA drive. The firmware provides a virtualised pool of storage which offers RAID-like functionality without RAID. If there are only two drives then data is mirrored. If there are three or four dives then data is striped across the four, as is parity data. Drobo does this automatically. The four drive slots, layered one above another, are covered by a glossy black semi transparent faceplate, attached magnetically to the Dobo's shiny black and curved enclosure; think Apple Macbook power cord attachment.

You can start with two drives and a capacity indicator, a row of ten blue LEDs seen through the bottom of the front panel shows you how much capacity is being used in ten percent increments. You drag and drop files and folders to Drobo on a Windows PC or server and it presents itself as just another drive, F: say.

There can be a maximum of four drives providing scalability up to 4TB of raw capacity using 1TB drives. You get about 60 percent of that available as usable capacity due to the RAID-like data protection measures.

Drobo can be backed up to tape but it is often used on its own as the final storage holder, because of its data protection features.

There is no host software, Drobo presenting itself as just another USB-connected external drive.

The product works with Macs; it's certified to work with the Leopard version of the Mac OS and its Time Machine backup application. In fact it's available directly from the Apple Store for $499 for the enclosure and software (£299 ex-VAT in the UK). You populate it with drives yourself.

In use Time Machine 'owns' the drive and files are retrieved from it using the Time Machine interface. An added benefit is that one Drobo can be used to backup several Macs on a network. There's no equivalent Windows backup application support.

Drive failure

When capacity usage rises past 85 percent or so then the Drobo software (firmware) alerts you that another drive is needed. Buy one and push it into a waiting slot for Drobo to then format it if needed, and then spread its data across the expanded drive set. While it does this drive read activity by applications is not affected. Video playback, for example, continues uninterrupted while a new drive is being assimilated.

With more than one drive Drobo can recover from a single dive failure.

Drobo drives are hot-swappable. If a drive fails then its status light, seen through the front panel, turns from green to red. Remove the panel, release the drive catch, pull it out, slot in a replacement. That's all you need to do. Drobo assimilates the new drive and rebuilds its dataset across the new drive configuration. It works with the drive's SMART interface too.

There is no need for management training and no need for a manual. Drobo is effectively self-managing and self-healing.

The Drobo company and market

Barrall's Drobo has had a second round of venture capital funding. It has sold about 7,000 systems since its launch in the summer. Product is manufactured in USA and in the far East.

Its market is the prosumer and SOHO (small office, home office) professionals and also education. It has built up an enthusiastic following with media professionals - the Apple connection, who use their Drobos as a digital media repository and recommend its use as a safe place to store media files without the hassle and difficult of tape.

The company has recruited serious storage professionals. Daniel Stevenson is president. Jim Schaff is director of marketing. Its chief technology officer is Julian Terry, a co-founder with Barrall and, like him, a Brit. Terry is responsible for much of the architecture of the product.

Jillian Mansolf, its SVP of sales, comes from a Dell and Snap Appliance (from Quantum to Adaptec) background. She has signed up 300 resellers in the USA. EMEA sales boss Andy Walski is an ex-Quantum staffer.

The company operates a 2-tier distribution model and has signed up CMS as a distributor for the UK. Walski is looking to sign up resellers who could both sell the basic product and offer bundles, the Drobo enclosure plus drives. There is one existing UK reseller; VCI Systems, which has sold about 250 systems. Walski wants to get to about 100 UK resellers. He also wants a distributor for the Nordic countries.

Drobo is not generally interested in the retail market and is looking more at Misco-type organisations. We shouldn't look for it PC World or Staples.

It's not clear how the product could grow. It could add capacity by growing horizontally, with four more bays on a side. Or it could stack four more bays on top although that might make it less stable. As drives become cheaper this capacity growth route is possible.

Will it grow to become networked? At the moment Drobo offers a very usable RAID replacement for prosumers and SOHO professionals and also he education market, who all prize ease of use enough to pay the premium over a DIY RAID system with its complexity of use.

Would this translate into the NAS market with vigorous sellers of low-cost systems like Iomega? Possibly but it would be a harder sell and the total volumes would probably be lower than in the existing prosumer/SOHO/education market. Drobo occupies a new and defendable and, I think, dependable, storage market niche. It will rapidly build a base in that and could easily attain 50,000 installed systems by the second half of next year and 100,000 in 2009.