Abstract
A digital computer system includes a master mass storage subsystem and a slave mass storage subsystem which provides mirrored storage for the master mass storage subsystem. One or more host computer systems can access information in the master mass storage subsystem to retrieve information from, and update information stored in, the master mass storage subsystem. When a host computer accesses information in the master mass storage subsystem, the information is cached in the master mass storage subsystem's cache memory, and when the information is updated, the update information will be updated in both mass storage subsystem's cache memories prior to being stored in their respective storage devices. When a host computer wishes to retrieve information, if the information is not in the cache of the master mass storage subsystem, if the information is still in the cache of the slave mass storage subsystem from a prior update operation, the host computer will enable the information to be transferred from the slave mass storage subsystem to the master mass storage subsystem for access by the host computer. Otherwise (that is, if the information is not in the cache of the master mass storage subsystem), the host computer will enable the information to be retrieved from the master mass storage subsystem's storage devices and cached in the master mass storage subsystems's cache memory prior to being retrieved by the host computer.
| Original language | English GB |
|---|---|
| Patent number | US6275897 |
| IPC | G06F 12/ 08 A I |
| Priority date | 17/06/97 |
| State | Published - 14 Aug 2001 |