LaCie’s Little Big Disk Quadra is a portable, bus-powered hard drive featuring two 250GB mechanisms striped in a RAID 0 configuration.

The built-in connectors include a pair of FireWire 800 ports, a USB 2.0 port and an eSATA port. LaCie includes a special cable for connecting one of the two FireWire 800 ports to a FireWire 400 port on your Mac.

The drive works with Apple’s Time Machine backup utility, but also includes LaCie’s 1-Click Backup Software, and EMC’s Retrospect Express. LaCie’s SilverKeeper backup software is included too, although it’s not compatible with OS 10.5 Leopard.

The Little Big Disk Quadra uses 2.5in notebook drives; notebook drives generally run at slower speeds than the full-sized 3.5in drives used in desktop external hard drives. The smaller drives also offer less capacity – 500GB is currently the largest single 2.5in drive available, while 3.5in drives come with as much as 1TB of capacity.

By using two hard drive mechanisms, the Little Big Disk Quadra can offer higher capacity than a standard portable hard drive, and by striping the drives into a RAID 0 configuration, the drive can also perform faster than a single drive. The downside to doubling up the drives is the expense – a desktop external storage device that uses a single mechanism, like LaCie’s 500GB d2 Quadra Hard Disk, costs less than half the price of the portable 500GB Little Big Disk Quadra (though the d2 Quadra isn’t as portable).

We tested the drive using all four interfaces on a Mac Pro 2.66GHz system running OS X 10.5.3. We found, as usual, that the eSATA results were the fastest. Unfortunately, no Mac ships with eSATA ports; you’ll need to buy a third-party eSATA card if you have a Mac Pro or MacBook Pro. Also, eSATA connections don’t supply bus power to the drive like FireWire does, which means you’ll need to use the included external power brick.

The second fastest results came from our FireWire 800 tests, which were between 6 and 15 per cent slower than eSATA. FireWire 400 was slower than FireWire 800, and USB 2.0 was slower still. While USB 2.0 supplies bus power, it’s not enough to keep this drive spinning, so you need to use the AC adaptor.

Compared to the LaCie d2 Quadra, the Little Big Disk Quadra was slower across the board, but not by much. The biggest performance gap was in the low-memory Photoshop tests, which showed the Little Big Disk taking nearly a minute longer than the d2 Quadra with each connection type.