Information Technology Reference
In-Depth Information
3.4.1 Cost/Benefit Modelling
It is very hard to model the costs of digital preservation [
17
], and even more difficult
to evaluate possible benefits. However it is worth discussing at least some of the
costs at this point to illustrate the point.
One of the simplest costs which one may try to estimate is that of storage. The
argument sometimes used is that the cost of a unit of storage reduces by 50% each
technology cycle (say 3 years). Suppose that the initial cost is £X. If at each cycle
one buys new hardware then one spends $X/2 in 3 year's time, £X/4 after a further
3 years, and so on. Therefore one would spend
£X
+
£X
/
2
+
£X
/
4
+
£X
/
8
+
......
.
=
£2X in total
Thus one can argue that the hardware cost is at least controlled.
However each 3 years the amount of data may easily have increased by, say, a
factor of 8, thus the cost keeping all the data would be:
=
∗
X
X
+
X
/
2
+
X
/
4
+
...
8
∗
X
8
∗
X
8
∗
X
/
2
+
/
4
+
...
64
∗
X
32
∗
X
/
+
...
4
Thus one can see that there is a real danger that the growth of data volumes may
easily swamp the cost savings introduced by new technologies. Moreover the cost
of personnel, and, more importantly, the cost of preserving the information rather
than simply keeping the bits, has been left out of the calculations.
More complex modelling is available based on cost data from real, anonymised,
archives [
18
]. However the cost models which are available omit the cost of
maintaining understandability, which could be labour intensive.
The Blue Ribbon Task Force on Sustainable Preservation and Access [
19
] has
looked at the broader view and identifies the fact that one can effectively purchase
“future options” without making an indefinite committment.
3.4.2 Future Generations
Although preserving our digital heritage for future generations is a laudable ambi-
tion, it must be admitted that those future generations have two great weaknesses (1)
they do not (yet) have a vote and (2) they do not (yet) pay taxes! As a result other
priorities can overwhelm our ambitions, no matter how laudable.
Clearly one cannot preserve everything and there are always more or less formal
mechanisms to choose what to keep and what to leave to decay (or leave for someone
else to preserve); it may be that the availability of funding determines what stays and
what goes and, in the long term, if money runs out then the whole of the collection
could die.
