Patent ID: 6070251
Filing Date: 2000-05-30
Classification: G06F

Abstract:
An apparatus, responsive to a host, for high availability and caching data storage devices, comprising:a primary controller;a secondary controller having the same address as that of the primary controller, the secondary controller being linked to the primary controller for synchronization, the synchronization including sending a request by the secondary controller to the primary controller for additional data when there is space available in a buffer of the secondary controller, and after the end of a command it receives, returning a pending status from the secondary controller to the primary controller, wherein synchronization prevents a data over-run condition from occurring;a switching circuit coupled to the primary and secondary controllers; anda control circuit coupled to the switching circuit such that in a normal operation the control circuit sets the switching circuit so that the primary controller receives and responds to input data supplied from the host and the secondary controller receives the input data, and such that in a fail-over operation in which the primary controller fails the control circuit sets the switching circuit so that the primary controller is disabled and the secondary controller receives and responds to the input data supplied from the host.