In addition to risk evaluation, IT managers should also consider whether they will be "any better off at the end of the day."

"Do I need to employ plumbers and the plumber unblocks four drains a month, or when I have a major plumbing job I call in a contractor?" Knowles said.

"Open source in some cases will deliver exactly what I want cheaply and quickly. In another case it might be I have to develop a whole lot of skills and knowledge and re-invent a whole lot of stuff that's already available in a box. It is a trade-off and we certainly look at open source from that point of view."

On the apparent rise in prominence of open source, Knowles said it is taking "a long time to be disruptive" and its publicity is "an advocacy of those who wish to [push] open source."