The work deals with the reconfiguration of computer system, which was designed to provide services from a strictly defined set. We assume that the system is fully usable, as long as each randomly appearing request to perform any service from this set will be handled. When such a request occurs, the technical resources required for its fulfillment must be allocated to the service. In the general case, the same technical resources can be dedicated to perform various services at different moments of time. Therefore, it is advisable to introduce abstract resources, so-called functional ones, representing particular types of actual technical resources. Functional resources mediate in linking the services and technical resources required to perform them. One functional resource can be associated with only one service, whereas it can be performed by various technical resources. Each set of pairs <service, functional resource>, constituting a subset of the full set of such pairs, determined at the design stage of the system, creates the so-called the system’s functional structure. In the case of damage of technical resource, it cannot be ruled out that it is impossible to maintain full usability of the system, i.e. to create a complete usable structure. However, as a rule, it will be possible to create more than one of its substructures, each of them provides support for service requests from a subset of the established set of services. If it is permissible to provide services to a limited extent for established subsets of services and for each of them a loss function resulting from the inability to provide a given service was specified, the system should be reconfigured (using available technical resources) so as to create a usable structure, at which potential losses will be the smallest..

The results of previous works are as follows:

• an algorithm for interactive fixing acceptable substructures by a user, reducing to the necessary minimum the number of required indications of service subsets (n services is 2ⁿ possible subsets). Indeed, the choice comes down to establish vectors of minimal reliability functions. That algorithm has been implemented,

• a general algorithm for determining optimal functional substructures at a given state of fitness of the system. It can be the basis for the design of the layer for controlling automated system reconfiguration.

The presented approach allows to reduce losses in the case of a lack of full possibilities of supplying services by the system. The proposed method, after some extensions, can be applied to reconfigure non-computer systems, e.g. the state security system.