Development cost versus maintenance cost

Question

I'm trying to explain the ratio of development versus maintenance costs to our sales department, and currently I have mostly my gut feeling that we spend about 60% of the time with maintenance.

We have some persons on the team who tends to sell custom solutions, that we have to build, and if the sales people doesn't understand the total cost of development, then they will not be able to sell for realistic prices.

Another "problem" is that we are expanding our service, and have a need to refactor some of the underlying infrastructure in order to reduce time to market and other measure points.

Do you have any good suggestions on what I should refer too in order to build a solid argument? And what points should i bring up in order to give them a good understanding of the problem?

Maybe there is some great text out there somewhere that I can point to.

Answer 1

Try getting them to think of software as a car. It may only take a couple of weeks or a month to build it, but whilst it is in use over the following weeks, months and years there is maintenance which will be required. Maybe it's just routine maintenance to keep things running smoothly; but it could also be emergency maintenance when it does something unexpected and needs fixing.

Similarly, it may be all fine when you first get it, but after a little use it will need polishing up to make it how you expected it to be all the time.

Answer 2

Study the concept of technical debt. Also, try to hang out with sales folks. Chances are that they are not evil or do not care; they just have been exposed to different stuff, have different skills and interests than you. Soft skills matter plenty. The biggest mistakes would be letting them know that "they do not understand computers". The easiest sales guy I ever worked with was ex-QA, so he got a lot of stuff. By the way, the job of sales folks is to bend the truth and keep those dollars coming. It is a delicate balance between not incurring too much technical debt, and not missing business opportunities.

Answer 3

In "Frequently Forgotten Fundamental Facts about Software Engineering" by Robert L. Glass, (an article in IEEE Software May/June 2001), He talks about softwares "60/60" rule, that is that maintenance typically consumes 40 to 80% (60% average) of software costs, and then that enhancement is responsible for roughly 60% of software maintenance costs, while error correction is about 17%.

Another source (which looks like a PhD proposal perhaps? but has a lot of references and statistics if thats your cup of tea) Software Development Vs Maintenance