Efficient preservation of the ordering of write data within a subsystem that does not otherwise guarantee preservation of such ordering

Abstract

A technique for efficiently preserving the ordering of data being written to a nonvolatile memory through a subsystem of a network storage system in the event of a power disruption, where the subsystem does not inherently guarantee that the ordering of the data will be preserved. The subsystem can be, for example, a memory controller hub. During normal operation of the system, data is written to the nonvolatile memory without flushing the data to the nonvolatile memory. In response to a power disruption in the system, data sources in the system that can initiate write transactions destined for the nonvolatile memory are inhibited from initiating write transactions destined for the nonvolatile memory, and pending write data within the subsystem is allowed to be committed to the nonvolatile memory. The nonvolatile memory is then placed into a self-refresh state.