Digital Preservation Essentials is one of the latest installments in Trends in Archives Practice, the Society of American Archivists' evolving modular series intended to fill significant gaps in the archival literature. The series currently covers topics that include themes of archival arrangement and description, appraisal and acquisition strategies, becoming a trusted digital repository, rights in the digital era, teaching with primary sources, and this volume on digital preservation basics. Erin O'Meara and Kate Stratton's two modules—“Preserving Digital Objects” and “Digital Preservation Storage”—in this slim volume pack a punch, proving to be engaging and accessible. Case studies, recommended readings, and glossaries enhance the modules. As such, they should enable novices to begin developing a preservation program, as well as provide experienced professionals a handy reference guide. As Kyle Rimkus notes in his introduction, O'Meara and Stratton go to great lengths to not overindulge in “acronyms and techno-jargon,” taking the opportunity to “define the necessary terms succinctly and articulate key concepts in a clear, comprehensible way” (p. 2). The “Preserving Digital Objects” module provides an overview of the digital preservation milieu, standards, actions, tools, and metadata, while the “Digital Preservation Storage” module focuses on what Rimkus refers to as the “first line of defense in any good digital preservation program” (p. 3).

I have often likened that sense of panic that arises when someone mentions digital preservation to my first time appraising a power plant several decades and a career ago. As a novice appraiser, with about nine months of experience under my belt, I was sent with a partner to appraise the University of Iowa's utilities. When we walked into the cavernous power plant with several giant generators, pumps, what seemed like miles of piping and conduit, and all sorts of switches, electrical gear, and who knows what, we were like deer caught in the headlights—aaah!! Where should we start? What is this stuff? What should we do? We finally asked the right question: who should we call? No, not Ghostbusters—we contacted the main office and explained we were out of our depth, could they send someone experienced to help us? They did, and while that person did explain what the various types of equipment were and what pertinent information we needed to gather to effectively develop appraisal values, he taught me an even more valuable lesson—don't panic, take a deep breath, pick a point in the room, start with something you know, and begin to work your way around until you have captured everything. We need to approach digital preservation the same way—don't panic! Pick a familiar point to start with; do something as opposed to doing nothing at all.

As that seasoned appraiser was my lifeline, module 12, “Preserving Digital Objects” could be yours. O'Meara and Stratton accurately suggest that “The preservation of digital objects is best approached incrementally, collaboratively, and iteratively. Practical approaches to begin to address basic levels of preservation can start small and build over time” (p. 12). O'Meara brings more than a decade of electronic records archival experience to bear on the subject, while Stratton adds collection development and donor relations experience for largely born-digital collections. Starting with an explanation of the National Digital Stewardship Alliance's (NDSA) “Levels of Preservation,” they extend the notion of starting small and working one's way to embracing the Open Archival Information System (OAIS) reference model. Their basic and practical explanation of the OAIS model grounds it in relatable day-to-day archival activities. The module also discusses trusted digital repositories, preservation actions in context, digital object description, management systems and tools (including a comparison matrix similar to the Digital POWRR Tool Grid1), and a brief list of recommendations for getting started along with a pair of real-world examples.

In module 13, “Digital Preservation Storage,” O'Meara and Stratton make the case that “. . . while digital preservation includes many activities and components, perhaps none is as central to the ultimate success of the endeavor as the storage of digital objects and data intended for preservation, since proper storage lays the foundation for other actions that archivists must take to preserve digital records” (p. 78). Besides picking up this book (or a similar tome), this is that first easy baby step—that starting point in the power plant appraisal—that any archivist or institution can take without even having developed a robust preservation policy or framework. Furthermore, the authors point to the need for vigilance, in that digital preservation is not really ever fully accomplished; it is not “set and forget,” but “requires monitoring, replacement planning and budgeting” (p. 79). The module does an admirable job of discussing best practices and mitigation strategies, including the need for a data exit strategy when working with vendor-supplied storage systems.

O'Meara and Stratton provide an overview of currently available storage options including optical media, hard disk/spinning disk, solid state, and tape, together with implementing tiered storage solutions and examples of storage service providers. This discussion features a concise set of pros and cons for various storage strategies. The authors articulate the need to document storage requirements—from levels of replication to access needs to contractual and/or statutory obligations among others—as well as to develop a cost model for an organization's digital preservation program. While they identify a couple of good models to consider, I felt this area would have benefited from an illustrative example or two.

Both modules are accompanied by various appendixes, including a list of recommended readings and glossaries that have only the slightest redundancies. The recommended reading list is especially useful as the majority of the resources are Web accessible. This is important for archivists and/or archival institutions that may not have the resources for costly technical tomes or access via an academic/research library. The glossaries are useful in and of themselves, but the highlighted text throughout the modules indicates which terms have also been defined in one of the two glossaries.

The other common element to the appendixes are the case studies that are presented as excerpts of extended interviews. Contributors include Greg Jansen, Carol Kussmann, Tim Marconi, Sibyl Schaefer, Jamie Schumacher, Jill Sexton, Lynne Thomas, and Meg Tuomala. Module 12 offers two views of digital preservation programs from the perspective of the Rockefeller Center Archives and the University of North Carolina–Chapel Hill. Module 13 spotlights three perspectives on digital preservation storage strategies with accounts from the University of California at San Diego Library and Chronopolis, the University of Minnesota Libraries, and the Northern Illinois University Libraries. It would have been interesting to hear as well from a truly small repository and/or a lone arranger who is having success with digital preservation.

Module 12 provides an additional two appendixes pertaining to metadata: one explains preservation metadata, its necessity, and potential tools, and the other provides examples of metadata schemas. As with the rest of this volume, the authors offer a concise and accessible explanation of metadata necessary for digital preservation; however, I would suggest to the editors of this series that this is an area ripe for its own thematic volume and set of modules.

While not as deep a dive into practical day-to-day digital preservation tasks and activities as, say, Adrian Brown's Practical Digital Preservation: A How-to Guide for Organizations of Any Size (ALA Neal-Schuman, 2013), this volume lives up to its title Digital Preservation Essentials, and it should be an essential reference on every archivist's and archival repository's shelf. So pick it up, read it, and find your point to start!

1 Digital Preservation Tool Grid, http://digitalpowrr.niu.edu/tool-grid.