Cache/disk subsystem with acquire write command
US4423479A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 14, 1980 |
| Grant date | Dec 27, 1983 |
| Priority date | — |
| Expiry date | Nov 14, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F12/0866
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A cache/disk subsystem includes a host processor, a cache store, a disk drive device for driving a disk, and a storage control unit for controlling the transfer of data between the host, disk and cache store. The cache store holds segments of data which have been read from, or are to be written to, the disk. When the host issues a normal WRITE command to the storage control unit and none or a part only of the data from the disk space specified by the command is resident in the cache store, the segment or segments of data in the disk space are staged into the cache store and overlayed with data from the host. A directory in the host keeps track of the disk segments previously written to. When the host is ready to issue a WRITE command it checks the directory and, if the segment or segments to be written to have not previously been written to, then the host issues an ACQUIRE WRITE command. The storage control unit includes controls responsive to an ACQUIRE WRITE command for bypassing the staging operation. The storage control unit also includes circuits for converting a normal WRITE command to an ACQUIRE WRITE command when the beginning and ending addresses of a normal WRITE command …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.