Remote data mirroring having preselection of automatic recovery or intervention required when a disruption is detected

摘要: Two data storage systems are interconnected by a link for remote mirroring of data. Each volume is configured as local, primary in remotely mirrored pair, or secondary pair. Normally, host computer directly accesses either local volume, and written to automatically sent over the corresponding volume. pair can operate selected synchronization mode including synchronous, semi-synchronous, adaptive copy--remote write pending, copy--disk. A number automatic non-automatic recovery mechanisms provided on logical basis desired level integrity degree operator application program involvement. If "volume domino" enabled access denied when other inaccessible. In "links mode, all volumes disrupted an all-links failure. The domino modes be used initiate application-based recovery, example, recovering file using log file. overwrite cache write-pending overwritten. "log-in-cache" multiple versions stored order recover from "rolling disaster".