• Licensing costs
• Hardware costs
• Human costs

All of these need to be assessed in order to see the true cost of any system. For some products, it turns out that the people and hardware costs dwarf the cost of the software.

The following chart quickly illustrates hidden costs of other SCM products.

COSTS	OTHER SCM	BITKEEPER
Software licenses	$-$$$$	$$$
Setup	$$-$$$$$	$
Hardware	$$$-$$$$$	$
Administration	$$-$$$$$	$
Third party databases (if needed)	$$$$	0

Licensing costs. Paid BitKeeper licenses are needed for each person who uses the software to make changes of any kind. Read-only users (people browsing the source, tracking progress, doing builds, etc.) still need a license but there is no charge for that license. In general, our software delivers productivity increases and time savings far in excess of the annual lease investment.

Hardware costs. Software requires hardware, and SCM software has traditionally required a great deal of hardware. Consider that virtually all other SCM systems have a centralized design where the SCM system runs on a single server. The performance of that server is a function of the server itself and the number of concurrent users. If there is only one user, a modest server will perform quite well, but as the number of users increases, the hardware must also be improved or performance becomes unacceptable. Unfortunately, the cost of performance is not linear. A system which is twice as fast is rarely only twice as costly, and a system which is ten times as fast is always much more than ten times as much.

The problem is obvious, a centralized SCM system will add hardware costs at what can be an exponential rate as the number of users increases. This translates into reasonable costs for 5-10 users and unreasonable costs for 100-1000 users.

BitKeeper does not have this problem because of its distributed model. The main repository is rarely used, work takes place in the child or grandchild repositories and then fans into the main repository. This model means that the hardware costs can be spread over a set of inexpensive PCs rather than a $300,000 SMP machine. BitMover hosts repositories used by thousands of developers on a single inexpensive server.

Human costs. Many SCM systems have traditionally required an administrator for every 10-20 users. These administrators are critical when the SCM is a centralized single point of failure. If an administrator costs $200,000 (salary, benefits, and other overhead) and one is needed for every 20 users, that is a not-so-hidden additional cost of $10,000/user/year. One may argue that a well run installation could do better, perhaps one administrator per 100 users, but that is still an additional $2,000/user/year. BitKeeper eliminates the need for an administrator, it has no single point of failure. The savings realized by not needing an administrator to nursemaid the SCM server will easily cover 100% of the cost of BitKeeper.