Using ReadyBoost-capable flash memory (NAND memory devices) for caching allows Windows Vista and later to service random disk reads with better performance than without the cache. This caching applies to all disk content, not just the page file or system DLLs. USB flash devices typically are faster than mechanical hard disks for random access, and slower than mechanical hard disks for sequential access. Gaining the benefit of caching implies that ReadyBoost will access the flash memory for random bits of data. Accordingly, ReadyBoost includes logic that recognizes large, sequential read requests and has the hard disk service these requests instead.
