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:
Sep. 12, 2000
Filed:
Feb. 03, 1998
Ellen Marie Bauman, Rochester, MN (US);
Robert Edward Galbraith, Rochester, MN (US);
Mark A Johnson, Rochester, MN (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
For error recovery purposes, a backup copy of only a portion of the cache directory is maintained in non-volatile storage. Because only a portion of the cache directory is backup copied, a savings in storage space is realized. The partial copy includes an indication of the storage locations on a storage device for which data is in the cache, and an indication of the state of the data, i.e., whether the data is in process of being read from the cache by the processor, is in process of being written to the cache by the processor, is in the process of being destaged from the cache to the storage device, or none of the above. Only certain changes to the state of the cache cause a backup copy of a portion of the cache directory to be saved; other changes to the state of the cache do not cause the portion of the cache directory to be saved in non-volatile storage. This saves processing time by limiting the number of times that data is copied to the cache.