Tuesday, June 14, 2011

Digital Preservation Series, Part 4 – Solutions, cont.

To continue on my topic from the last post about solutions to the digital preservation conundrum, let me focus now on storage and digital preservation management.

This is one of the biggest questions that many people have about digital preservation. If storage media, such as hard drives and magnetic tapes, are bound to fail over time, what can we do to make sure the information on them isn’t lost? The first and most important answer is redundant backup. Digital content should never, ever be stored in only one location or on one type of storage media. For example, if one copy of a file is stored on a server in Florida, there might be another copy on a server in California and another copy on magnetic tapes in France, and another copy on a different type of server in Ohio.

While this example might be overkill for personal collections, storing identical copies of digital resources on different types of storage media (such as hard drives, tapes, and DVDs) and in different geographic locations (which could be as far-reaching as different countries or simply different buildings in a single town, depending on the kind of data being stored) helps ensure that if a disaster ruins one copy, there will still be another to use. The Library’s digital resources are stored on servers that are backed up in another location with its own generator in case of power failure.

The other important note about storage is that there are many different kinds of storage media, ranging from CDs and DVDs to very expensive liquid-cooled servers. When selecting a storage medium for digital materials, it’s important to choose a type and brand that has a reputation for good quality. While all media will fail eventually, higher-quality media will last longer and ultimately help reduce the cost of replacing media over time.

Of course, copies alone will not keep digital materials safe. Even if disaster is averted, there’s still the issue of bit rot to deal with. And that’s why we need a set of…

Preservation Management Activities
These are actions that are regularly performed on digital files to make sure they are still usable. There are many, many ongoing preservation actions, but some of the most important include:

  • Validation – checking to make sure the file is still exactly what its metadata says it is, and that none of its bits have been damaged or lost. If the validation fails, then another copy (thank goodness we have those redundant backups!) can replace the damaged one.
  • Migration – this includes both format migration, where a file is converted to a newer format if the software it relies on is becoming outdated, and migration to new storage media when old media are in danger of deterioration.
  • Maintenance of equipment – all of the hardware used to store and view digital resources, software necessary to view resources that can’t be converted to open file formats, and technical infrastructure such as networks and updates, have to be actively maintained all the time.
  • Security – it’s important to have security measures in place, such as encryption, active virus scanning, and strong firewalls, to prevent digital files from being inadvertently or maliciously damaged by other people. Just as you (hopefully) wouldn’t store your important family documents in an unlocked and easily accessible location, important digital files should be given the same measure of protection.

Ongoing Learning
On top of all the activities listed above, digital preservation managers have to constantly monitor the information science field to make sure they are following the latest standards, new technologies, and accepted best practices. We always have to know what’s happening now and what technical innovations are just over the horizon, because there are always new threats and new ways that old digital collections can be rendered useless to future researchers. In the words of Alastor “Mad Eye” Moody in Harry Potter and The Goblet of Fire, "constant vigilance" must be observed to ward off any potential hazards.

Fortunately for us here at Dartmouth, we aren’t alone in the digital preservation boat. There are many organizations that are conducting research, defining standards, and creating tool to help preserve these relatively newfangled digital materials. In my next and final post, I’ll talk about some of the great resources out there that are leading the way in digital preservation.

Written by Helen Bailey

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