State of the Art: Long-Term Storage Strategy

Once you've gotten upper management on board, get your software and hardware systems team leaders involved in the planning. This will ensure that no one gets blindsided by the project. Then work with your business units to identify what data needs to be saved long term. Financial reports, for example, probably need to be stored, while five-year-old e-mail messages about a co-worker's birthday celebration clearly are nonessential. Get your legal department involved in the process, too, to ensure data that needs to be retained by law is properly stored.

Don't forget to determine retrieval requirements. The rule of thumb for data retrieval: The faster you want it, the more the equipment and software will cost you. Find out how long each business unit needs its data stored, when it will become obsolete and when it can be discarded. This information provides a baseline for time and capacity, which will help you purchase the appropriate storage hardware.The reality is that no matter what kind of long-term storage technology you choose, someday it will be obsolete. Choosing carefully today can ease the pain of the evitable migration.

One option is simple tape technology. Although tape shelf life varies, most tapes survive 20 years or more if they're stored properly. But even the toughest tape is worthless if the drive required to read it breaks. Tape formats such as DLT, LTO, AIT and VXA have built-in backward read compatibility, but beware: Look closely at the manufacturer's road map for the drive's read compatibility. Formats early in their lives will have better long-term read options than older formats. Another trade-off is that tape is slow, so if you need to get to your data quickly, it's probably not the format for you. Tape works best when you want inexpensive storage with a long shelf life.

Another option is professional optical media formats such as UDO (Ultra Density Optical), which are designed to withstand the years. Their road maps are carefully planned to give the user maximum life on a given media, in both read mechanism compatibility and durability of the optical medium. The nonlinear nature of professional optical makes it much faster than linear tape. Hewlett-Packard offers a full line of optical drive jukeboxes for this application.Meanwhile, pricing and speed improvements have made hard-disk technology a hot commodity. But hard disks are just not suited for long-term storage. A disk drive's life expectancy is measured in power-on hours, not shelf life. If you have a failed hard disk that's been shelved, you can't simply move the media to a working read/write mechanism, because disk drives marry the read/write mechanism to the media in a sealed environment. There's also the problem of the manufacturer-specific encoding for RAID schemes. And it doesn't make sense to keep hard disks constantly spinning for rarely-accessed archived data, either. Plus the heat can wreak havoc on your electronics.

DVD has gotten a lot of attention, too. But the quality and longevity of burnable DVD media are still an unknown. Plus, the current red-laser DVD technology is too small for most enterprise applications, though the new blue-laser format may prove better. UDO is already fulfilling this function for large enterprises; blue-laser DVD might make sense for small businesses.

Eye on ILM

Then there's the software that ties together your long-term data storage strategy. No single software tool does it all just yet, so enterprises end up with separate tools for managing stored data from different applications, like database-management systems and e-mail. These tools archive and restore data; some even offer data migration to different storage platforms as the data ages. IBM, Veritas, Legato and HP offer tools for specific applications and databases, but using different tools can cost you more in time and effort to learn different interfaces and terminologies. The ultimate solution, of course, is true ILM (information life-cycle management) but that's still a pipe dream (see "ILM: Panacea or Proprietary Poison?" for more on this topic).

Storage vendors and the SNIA (Storage Networking Industry Association), meanwhile, are working on specifications for a single tool for managing your long-term data. That's because even if you define your business requirements to a tee and get the best hardware, your long-term storage system will fall flat if you don't have a way to quickly find archived data.Steven J. Schuchart Jr. is a senior technology editor for Network Computing and a contributing editor to Storage Pipeline. He previously worked as a network architect for a general retail firm, a PC and electronics technician and a computer retail store manager. Write to him at [email protected].

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