How much will it cost to preserve my content?
The question could be bounced back: how long do you want to preserve something? Clearly it will cost more to keep something for 1000 years than for 10 years. The first major surprise in dealing seriously with long-term costs is that ‘forever costs’ can be calculated, and they are not infinite. How can that be? If something costs so much per year, then for an infinite number of years it costs an infinite amount, right?
Yes, but. First of all, if the costs decrease year on year, then the sum is finite — a basic fact of mathematics that seems mysterious, but it is no more mysterious than the fact that the series 1 + 1/2 + 1/4 + 1/8 + 1/16 can be extended indefinitely, and the sum still never reaches 2 — because at each stage the amount being added is half the amount needed to reach 2.
The second reason is related, but has to do with increase rather than decrease in value. Money, in our economies, generally grows. A lump of money can be put somewhere where it earns interest. If the principle isn’t touched, that earning carries on indefinitely: a money pump. So even for a fixed cost per year (rather than a shrinking one) — the calculation of the forever cost comes down to the calculation of the amount of money needed to be put aside to earn enough interest (enough net present value) to pay the annual costs, forever.
This answer may already sound complex, but without these complications we’d have to fall back on: “well, to keep something a long time will cost a lot of money” which isn’t insightful.
Preservation is everything needed to preserve access, to follow the UNESCO and CCAAA definition (1). That covers pretty much everything. In order to be more specific, the PrestoSpace terminology divides all this into two areas:
- actions that happen all the time, or very frequently. Keeping the air conditioning running is an example. These actions could also be called maintenance, to stress the idea that they have to happen, and can’t (safely) be put off.
- one-off or infrequent preservation actions, but still necessary to the existence of the items.
The first group of actions could be called conservation — and indeed was called conservation in the Presto series of projects. The only problem is that in other archive and museum fields fields conservation can be used for interventions: taking a book up to ‘the conservation workshop’ to give it a new binding, or taking an oil painting to have the canvas rehung and reframed. So this answer will stick with maintenance.
Digitisation is a major example of a preservation action, and costs for digitisation are the subject of a seperate Answer in this series. [see the FAQ on digitisation costs]
Maintenance would cover areas familiar to every librarian or archivist: the building, the shelves, environmental controls, cleaning and general upkeep, and associated staff costs. How much does all that cost? As a book on a shelf has a lot in common (so far as maintenance costs are concerned) with a tape or film on a shelf, we can turn to data from the general library world. In the UK there was a study of shelf costs compared to digital storage: LIFE-SHARE. For shelf costs they in turn relied on a paper published in 2010 in the USA: On the Cost of Keeping a Book (2).
We now come back to net present value, because that is how Courant and Nielsen were able to deal with long-term costs such as replacing a library building after 40 years. Their result gave an annual cost per book of between US $1 and $4, depending upon whether it was the more expensive open-access shelves, or the high-density ‘stacks’ that can’t be browsed and are harder to access, but make cheaper storage.
Audiovisual archives could be expected to be closer to the $1 figure, because of their use of high-density shelving. These annual costs may seem high, but they are in accord with figures from major archives associated with the PrestoCentre. If your situation doesn’t require covering the full cost of the building, your effective costs could be as much as 75% less (because 60% to 75% of the costs in the Courant and Nielsen study were for the buildin itself).
The second major surprise is that digital is now cheaper. This is clearly the case in the book world, as shown by Courant and Nielsen, and by the JISC-British Library LIFE studies and by LIFE-SHARE. A scanned book is typically a few gigabytes, and organisations such as the Hathi Trust will store it for from $0.25 to $0.40 per year depending upon scan resolution and whether the scans are monochrome or colour.
Store it how, with what guarantees and what indemnities if it all goes wrong? And what happens if they go bust, or a supplier of a key component goes bust? These are the real concerns in digital preservation: definition of a service that really meets the needs, covers the risks, and sets out all the information where all parties can see and understand it. The issue of defining what we mean by ‘digital preservation’ and ‘storage as a service’ is the area of real concern — not the current price of LTO tapes or hard drives. Organisations doing their own digital storage also need to define what they mean and define the service they want to deliver to themselves. It may be even more vital for such an organisation, because they may be novices.
There is a wealth of information in the PrestoCentre Resources. A six page introduction is the Digest: Audiovisual preservation strategies, data models and value-chains; another basic reference (only two pages) is Preservation of digital audiovisual content.
(1) Edmondson, Ray “Audiovisual archiving: philosophy and principles” UNESCO, 2004. V3 is 2016
(2) Paul N. Courant and Matthew “Buzzy” Nielsen, in The Idea of Order: Transforming Research Collections for 21st Century Scholarship, Council on Library and Information Resources (2010)