Shared disk clones

A computer-readable storage medium containing a program which, when executed, performs an operation comprising:

• providing a primary database server and a clone of the primary database server to shadow database processing actions performed by the primary database server, wherein both the primary database server and the clone have access to a shared storage device;
• sharing access from the primary database server and the clone to database pages stored on the shared storage device and access to a log file that stores entries corresponding to a sequence of database processing actions performed by the primary database server;
• receiving a first log sequence number (LSN) representing an entry in the sequence of database processing actions;
• reading the log file to retrieve the log entries in the log file sequentially prior to the entry represented by the first LSN;
• performing at least some of the sequence of database processing actions specified by the log entries, wherein the performing includes retrieving at least one database page from the database pages;
• storing the at least one database page in a page buffer on the clone;
• and
• sending a message to the primary database server that includes a second LSN specifying a last log entry processed by the clone, wherein the primary database server is configured to flush pages from a page buffer on the primary database server to the shared storage device based upon how far the clone has progressed through the sequence of database processing actions specified by the log entries.

A computing device, comprising:

• a processor;
• a shared storage device;
• and
• a memory containing a program, which when executed on the processor, performs an operation comprising:
• providing a primary database server and a clone of the primary database server to shadow database processing actions performed by the primary database server, wherein both the primary database server and the clone have access to a shared storage device;
• sharing access from the primary database server and the clone to database pages stored on the shared storage device and access to a log file that stores entries corresponding to a sequence of database processing actions performed by the primary database server,
• receiving a first log sequence number (LSN) representing an entry in the sequence of database processing actions,
• reading the log file to retrieve the log entries in the log file sequentially prior to the entry represented by the first LSN,
• performing at least some of the sequence of database processing actions specified by the log entries, wherein the performing includes retrieving at least one database page from the database pages;
• storing the at least one database page in a page buffer on the clone, and
• sending a message to the primary database server that includes a second LSN specifying a last log entry processed by the clone, wherein the primary database server is configured to flush pages from a page buffer on the primary database server to the shared storage device based upon how far the clone has progressed through the sequence of database processing actions specified by the log entries.