Similar dependency models are needed when determining availability requirements on sub-services (looking from a top down perspective) respectively for the calculation of service availability from the availability of underlying services (bottom up), as described in [#!kais99p!#].
Knowledge of dependencies between systems may be of further use
for the prediction of impacts on other systems due to
management operations. This is of particular interest in typical
maintenance scenarios, where a server has to be shut
down temporarily: It is essential to know, resp. to simulate the
effects on other systems beforehand.
Further investigations of advantages can be found in [#!pemt95!#] and
[#!clem94!#]. A common result of their and others' examinations is
that--assuming models do already exist--great benefits can be
achieved for management tasks. For our purposes, following major
advantages for the practical utilization of environmental models can be
resumed; they:
More applications of environmental models emerge if the algorithm used for their generation allows--like the one presented in section --frequent iteration of the modeling process in certain time intervals. This enables the analysis of changes of dependencies in the managed environment during that time. This is, e.g., useful for fault prediction, because significant changes in the overall system behavior are detected through emerging or disappearing dependencies. This often reflects errors that are already present in currently unused parts of a service which may later (under different usage conditions) effect its usability. The detected changes may also be used to point out forbidden actions or disallowed use of services. This is helpful especially for intrusion detection and to recognize service misuse.