1. A computer system comprising: a storage apparatus for controlling data input to, or output from, one or more storage devices and generating an event when a failure occurs in at least one of a plurality of physical resources used for the control; one or more server devices for managing a plurality of virtual volumes, which are obtained by virtualizing a plurality of real volumes composed of a storage area of the storage device, and for generating an event when a failure occurs in at least one of a plurality of physical resources used for the management; a management server device for managing each virtual volume as an access target of an access requestor; and an event management device for managing at least the storage apparatus or the server device as a management target and managing an event generated by the management target; wherein when receiving the event from the management target, the event management device judges the content of the received event and identifies a virtual volume to be affected by the generation of the event; and if a service level that should be satisfied by the identified volume is defined for the identified virtual volume, the event management device identifies, based on the content of the received event, whether an incident in violation of the defined service level has occurred or not, and notifies the management server device of the identified content as an event based on an event filter.