Abstract: A method and a system for analyzing the operation of a parallel data system are disclosed. The history information of the access executed by a specific processor that has received a request for access to a plurality of data bases connected to a plurality of processors, the ID of the specific processor and the accessed data amount are collected and stored in a memory. The history information is compared with the time assumed from a predetermined time specified for the access to a unit amount of data in data bases, deciding whether the former is reasonable or longer than the latter. The transfer history information for the processor that has transferred an access request to the specific processor executing the access is compared with a predetermined transfer time specified for a unit amount of data, deciding whether the transfer time between the two processors is longer than an assumed transfer time.