At Trinity, we utilize multiple platforms and locations in order to ensure the long-term accessibility of our digital assets.
Preservation and stewardship starts long before items are stored -- workflows include metadata capture, creating digital assets with the ideal formats and sizes for archiving, and for having workflows in place for creation, transfer, or ingest. Having a place to store items for the long-term is a piece of long-term preservation, but is not the end-all. In fact, there is a term for items left in storage for the long-term without active stewardship -- benign negligence. Often, benign negligence leads to nasty surprises, such as a hard drive that will not read when it worked many times before, or digital images that have lost much of their information to bit rot. Lack of security might lead to human error, such as a coworker accidentally deleting files they think are not important, or accidentally moving items to another location, where they are now "lost."
Digital preservation is an ongoing workflow of management that begins before items come to the archive and continue long after they are ingested into it.
Due to its complexity and difficulty, true robust digital preservation is not always attainable. Rather than one set checklist, there are multiple stages to creating a digital preservation program. The National Digital Stewardship Alliance has four levels of preservation that can suit many institutions' resources and needs. At the simplest level, conducting an inventory of digital assets and creating redundant copies in multiple geographic locations is a good start. For example, having two or three copies -- one on a hard drive, one in cloud storage, and one locally so that if anything happens to one set, it can be replaced quickly. This satisfies the most basic digital preservation component, LOCKSS (lots of copies keeps stuff safe).