The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 20, 2002
Filed:
Jun. 23, 2000
Michael E. Nielson, Broomfield, CO (US);
Thomas E. Richardson, Golden, CO (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
The present invention provides a method and apparatus for providing battery-backed immediate write back cache for an array of disk drives in a computer system. Cooperation between a new replacement controller and a survivor controller is enabled so that write back cache operation can start immediately, and not be dependant on the battery condition in the replacement controller. Protection of the data through a single point of failure is maintained. When a controller fails, a replacement controller is installed and battery state information is exchanged. If any battery backup meets a predetermined threshold, all of the controllers run in the write back cache mode. However, if not one of the battery backups meets a predetermined threshold, all of the controllers run in the write through cache mode. Thus, the system does not need to wait for a replacement controller's battery backup to be reconditioned before the higher speed write back cache is used.