Optimize flash media for ReadyBoost in Windows Vista

SuperFetch, the innovative memory manager that handles disk caching for Windows Vista, uses an associated feature called Windows ReadyBoost as a secondary disk caching mechanism. SuperFetch utilizes ReadyBoost to store disk pages that can be randomly read more quickly out of Flash media than from rotating media (Figure 1).

Figure 1 ReadyBoost augments SuperFetch with a Flash disk cache .
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ReadyBoost caches I/O to and from the hard disk drive. One of the places that this is most visible is file swapping and demand paging. Although frequent usage of virtual memory is often viewed as the main contributor to a PC's poor performance, the inefficiency of the hard disk drive also plays a key role. The inefficiency comes from two areas: less-than-optimal memory content and latency associated with long seek-time on hard disk drives. SuperFetch and ReadyBoost address these performance bottlenecks by improving both memory match efficiency and disk cache speed. SuperFetch actively analyzes and optimizes the content of virtual memory and adds a "time" element to help caching the most relevant data at any given time. The result is a much more effective usage of disk cache.

ReadyBoost uses nonvolatile memory to reduce non-sequential access of a hard disk drive. The usage of Flash memory as a read-only cache for the hard disk drive greatly reduces latencies associated with random access of rotating media and makes cached data readily available when demand paging occurs. The performance gain provided by SuperFetch and ReadyBoost translates to tangible improvement in system responsiveness that is user observable, and the improvement is impacted by the bandwidth (speed in MB/s) provided by the Flash media.