The Drobo Mini and Drobo 5D portable storage drives are external storage ... cases, which allow external storage drives to be loaded inside. The cases don't come cheap, but offer fast data transfer in an attractive form factor.

The Drobo 5D, the Mini's bigger brother, has five bays and includes Thunderbolt and USB 3.0 ports. $200 cheaper, at $599, is the Drobo Mini. It's seemingly cheaper and almost equal in functionality, including four drives bays and weighs three pounds.

For comparison to recent stories, that's just a pound heavier than the Windows Pro for Surface tablet Microsoft unveiled.

The Mini has four lights to represent each drive, and an LED bar which represents how full the capacity of the Mini is. 2.5-inch drives go into spring-loaded slots sans screws or trays, so no resting the hard drive in place while it's secured like when building some PCs. Replacing a drive is just as simple: push it in, then pull it out. Another drive goes in exactly the same way as before.

One issue is the need for the AC adapter, which seems to slightly defeat the point of the Mini being the portable version of the 5D. The other issue is that if power goes, or the AC adapter becomes unplugged, there's the chance data will be lost. Presumably that's why four hard drives can be installed - if one blows, there's effectively three backup drives.

The Thunderbolt ports on the devices allow them to be paired with other external storage drives, and an SSD drive can be inserted on the bottom to give a noticeable speed boost. The 200/300MB per second data transfer speed is increased by 300 percent if a Solid State Drive is installed, which is quite the boost and comes in between 20,000-30,000MB a second. That's 2-3GB, a second.

For users who want to go crazy, more SSDs can be added for super fast speeds.

The Drobo 5D and Drobo Mini are available from July 2012, for $799 and $599 respectively. Potential owners can be notified when the devices become available.