Fast write operations

摘要

A technique is described for performing a fast write operation. A host write request, which would normally be serviced by an immediate physical write to a data storage device, is instead written to cache and nonvolatile storage in the data storage device controller. Then, the controller signals the host that the write operation is complete and does not update the physical data storage device until later. A journal log is also used to provide recovery capability in the event of system failure. This technique provides high performance for the units' operation while assuring integrity by keeping two copies of the write operation until the physical update transpires.