Billions and Billions of Bytes

In this week’s Technology & You column, I take a look at Microsoft’s new Windows Home Server which, among other things, can be a very good way to manage the vast amounts of inexpensive shared storage now becoming available for home networks. For most folks, the terabyte of storage (that’s a trillion bytes, or 1,000 gigabytes) available on the Home Server is more than they can fill. But don’t underestimate the amount of media you may accumulate, especially if you built a library of high-definition video. Fortunately, the Home Server includes USB 2.0 ports that allow you to add effectively unlimited storage.

One of the more interesting options for add-on storage is Drobo from Data Robotics. Build-it-yourself disk drive enclosures—boxes with power supplies and interface electronics to which you add your own drives—are readily available. Drobo is a four-bay drive enclosure with a big difference. It’s equipped with software that automatically manages storage and monitors the health of the drives. An empty Drobo sells for $499. Serial ATA drives (older IDE drives won’t work)range from around $50 for 80 gigabytes to more than $400 for 1 terabyte, the largest currently available.

Like traditional drive arrays, all the drives in a Drobo show up on the computer to which it is attached as a single large disk and all data are stored redundantly on at least two different drives for security. Unlike traditional setups, however, the drives do not have to be matched in size. You can use any number, up to four, and any combination of sizes, adding larger drives as small ones fill up.

Data robotics calls Drobo a "data robot," and while that may be something of an exaggeration, it does bring a new level of automation to storage management. Drobo monitors the health and capacity of its drives. If a drive shows signs of failure, Drobo will move data off it and warn you. It will do the same as a drive approaches capacity; once the data on a drive have been cleared, you can hot swap in a new, larger drive.

As with other redundant drive arrays, the total capacity of a Drobo system is less than the sum of the capacities of the installed drives. Data Robotics says the best estimate of total capacity is to disregard the largest drive in the system and sum the rest; if you have two 500 GB and two 750 GB drives, your effective capacity will be 500+500+750=1.75 TB.

In addition toe being useful as add-on storage for a Home Server, Drobo can be attached directly to a Mac or a Windows or Linux PC. A standalone network-attached version, in effect a sort of home server, is expected in 2008.

Before it's here, it's on the Bloomberg Terminal.