This paper presents a new access-density-based prefetching strategy to improve prefetching for the access patterns, which have not been dealt with in the current Linux read-ahead algorithm. At the same time, motivated by the existing algorithms, we propose a hybrid and efficient replacement algorithm to improve buffer cache performance. Firstly, we propose the following three metrics to evaluate the above access patterns: reading file data backwards, reading files in a stride way (leaving holes between two adjacent references), alternating references between multiple file regions and reading files randomly. Secondly, having explored the eight representative recency/frequency-based buffer cache replacement algorithms, we carry on a hybrid replacement algorithm. Finally, these experimental results demonstrate the importance for buffer cache research to take both file system prefetching and replacement algorithm into consideration.