While it is true that in general software doesn't wear out , this is not true for software thatinteracts with the Internet. Internet software definitely breaks downover time, not because of any analog to mechanical wear but because theInternet environment it operates in keeps changing.

There are three sorts of changes in the Internet environment thatmatter. First, protocols and other programs that interact with youevolve over time. Second, user expectations also evolve. Third and mostimportantly, the Internet threat environment itself keeps changing,

If you are going to charge for things , one ofthe eternal questions is whether you should use detailed usage chargesor simpler, 'flatter' ones. My personal thoughts run something likethis:

If you have a fixed service that you're expanding slowly (if atall), detailed charges theoretically extract the maximum value forit. However, they do so at the cost of driving away users who don't likethe unpredictability of their bills, and every so often you will havesomething go horribly wrong

Let us suppose, as a not entirely hypothetical example, that youare transplanting the system disks from a Solaris 10 install from aSunFire X2100 to a SunFire X2200. While both machines have four onboardnetwork ports, two Broadcom and two nVidia, they are not quite thesame hardware, enough so that if left to its own devices Solaris willconsider the new machine's NICs to be bge2 , bge3 , nge2 , and nge3 (instead of bge