United States Patent  [ii] Patent Number: 4,916,605
Beardsley et al.  Date of Patent: Apr. 10, 1990
 FAST WRITE OPERATIONS
 Inventors: Brent C. Beardsley, Tucson, Ariz.;
Michael D. Canon; Malcolm C.
Easton, both of San Jose, Calif.;
Michael H. Hartung, Tucson, Ariz.;
John H. Howard, San Jose, Calif.;
Robert H. Vosacek, Tucson, Ariz.
 Assignee: International Business Machines
Corporation, Armonk, N.Y.
 Appl. No.: 91,406
 Filed: Aug. 31, 1987
Related U.S. Application Data
 Continuation-in-part of Ser. No. 593,747, Mar. 27, 1984, abandoned.
 IntCl." G06F 13/00
 U.S. CI 364/200; 364/239;
 Field of Search ... 364/200 MS File, 900 MS File
 References Cited
U.S. PATENT DOCUMENTS
3,588,839 6/1971 Belady et al 364/200
4,020,466 4/1977 Cordi et al 364/200
4,523,206 6/1985 Sasscer 364/200
4,523,275 6/1985 Swenson et al 364/200
4,530,055 7/1985 Hamstra et al 364/200
4,598,357 7/1986 Swenson et al 364/200
A technique is described for performing a fast write operation. A host write request, which would normally be serviced by an immediate physical write to a data storage device, is instead written to cache and nonvolatile storage in the data storage device controller. Then, the controller signals the host that the write operation is complete and does not update the physical data storage device until later. A journal log is also used to provide recovery capability in the event of system failure. This technique provides high performance for the units' operation while assuring integrity by keeping two copies of the write operation until the physical update transpires.
IS Gaims, 8 Drawing Sheets