Disk Cache Replacement Algorithm for Storage Resource Managers in Data Grids

Abstract

We address the problem of cache replacement policies for Storage Resource Managers (SRMs) that are used in Data Grids. An SRM has a disk storage of bounded capacity that retains some N objects. A replacement policy is applied to determine which object in the cache needs to be evicted when space is needed. We define a utility function for ranking the candidate objects for eviction and then describe an efficient algorithm for computing the replacement policy based on this function. This computation takes time O (log N). We compare our policy with traditional replacement policies such as Least Frequently Used (LFU), Least Recently Used (LRU), LRU-K, Greedy Dual Size (GDS), etc., using simulations of both synthetic and real workloads of file accesses to tertiary storage. Our simulations of replacement policies account for delays in cache space reservation, data transfer and processing. The results obtained show that our proposed method is the most cost effective cache replacement policy for Storage Resource Managers (SRM).