SHARED DISK CLONES

摘要

In a high availability data processing system, a primary server may share a storage device with one or more clone systems. Each clone generally replicates the state of the primary server, but relies on the same disk-based storage as the primary server. Thus, the clone systems may provide a shadow of the primary server, ready to take over should the primary server fail. The clone systems may access a log file that includes entries reflecting the actions performed by the primary system. The primary server may flush entries from a log buffer maintained on the primary server to a log file stored on the shared disk-based storage. The primary server may also send a log sequence number to the clone systems, and the clone systems periodically transmit a log sequence number back to the primary server indicating how far through the log file a clone system has progressed.