Storage & Geographic Location
Summary/Best Practices
This NDSA category focuses on two things: (1) progressively reducing risk by storing multiple copies of data in dispersed geographic locations, and (2) storage documentation and planning.
When multiple copies are stored in different locations, copies can be recovered in the event or loss or damage to other copies. As the Digital Preservation Handbook explains, loss or damage might be caused by "fire, flood, failure to instigate or follow proper processes or procedure, malicious attack, media degradation, and obsolescence of storage systems and technologies." Risks will be unique to an institution and should be evaluated as a part of disaster planning.
A perfect storage system is not actually perfect if staff don't know how to recover data or if recovery is prohibitively expensive. Moving to levels 2, 3, and 4 involve documenting, monitoring, and planning for future systems.
Step by Step
Level 0 to Level 1
- Two complete copies that are not collocated
- For data on heterogeneous media (optical discs, hard drives, etc.) get the content off the medium and into your storage system
The first step toward level one is essentially making a backup, so that recovery is possible if one system fails. This could range from an external hard drive to regular computer back-ups to a storage system managed by your institution's IT department. At this stage, a second copy on external hard drives is preferable to nothing, but be aware that it will take some effort and organization to keep copies in sync.
Another part of achieving level one is to transfer content from heterogeneous media and onto a storage system. 'Heterogeneous media' might be floppy discs, CD-Rs, DVD-Rs, ad-hoc internal or external hard drives, and thumb or flash drives. These aren't appropriate storage spaces for digital preservation. Even opening files can potentially alter files or embedded metadata of files, so before you start working, read OCLC's You've Got to Walk Before You Can Run: First Steps for Managing Born-Digital Content Received on Physical Media.
Level 1 to Level 2
- At least three complete copies - At least one copy in a different geographic location
- Document your storage system(s) and storage media and what you need to use them
Increase the number of copies you store to three, with one copy in a different geographic location. This will allow recovery in the event of a local disaster like a fire, flooding, or sabotage. The form of the copies depends on the institution: cloud services might be the best option for some, others might enter into a reciprocal agreement with another institution or consortium, or use tape storage. A good discussion of the pros and cons of cloud storage can be found in the Digital Preservation Handbook.
Create documentation about your storage system. This could be as simple as describing your agreement or contract with your IT department, and might be included in your digital preservation plan. If you use an external service for storage, document the contract and terms and conditions for retrieving data. If there are expenses involved in retrieving data, document who pays.
Level 2 to Level 3
- At least one copy in a geographic location with a different disaster threat
- Obsolescence monitoring process for your storage system(s) and media
Make sure one copy of your data is stored in a location with a different disaster threat than the others. For example, an institution facing earthquakes as the highest threat might store a copy in a geographic region where tornados, not earthquakes are the greatest threat. This practice is about reducing risk: could both copies face different disasters at the same time? While possible, it is highly unlikely. Like the step from level 1 to level 2, institutions will need to implement this in a way that works for them. Cloud vendors and participation in digital preservation networks are both options. Institutions could also explore an Alliance-wide storage solution.
All storage systems will eventually become obsolete. Level 3 involves monitoring your system to be able to identify when the system is reaching the end of its lifespan. This does not necessarily have to be a complicated technical process: rely on your storage provider. For example, your IT department might know that a particular storage environment will need to be replaced within a certain timeframe. Document this so that you can follow up. If you rely on cloud storage, monitor communications and news about the industry so that you're aware of issues affecting your provider.
Level 3 to Level 4
- At least three copies in geographic locations with different disaster threats
- Have a comprehensive plan in place that will keep files and metadata on currently accessible media or systems
Further decrease risk by keeping three complete copies in locations with three different disaster threats. As with other levels, options include digital preservation networks or reciprocal agreements, purchasing cloud storage as an institution, or magnetic tape storage.
Have a plan in place for migration of the storage environment when it becomes obsolete. This means that you should not use a storage environment that doesn't allow for an exit strategy; know and document what would need to happen to get your data out. The plan might be a part of your general digital preservation plan.
Unless you manage your own storage, you do not necessarily need to have a technical plan; this will more likely be a contract or agreement with your storage provider (whether your institution's IT or an outside entity). This plan should address issues like: Who is responsible for the storage environment? Who pays for it? Is the funding stable? Who determines if and when to migrate? Who oversees the migration? Being able to make this plan requires a certain level of institutional communication and commitment. If there is no commitment to long term planning, this step might not be able to be fulfilled.