Hash routing partitions the entire URL space among a collection ofcooperating proxy caches. Each partition is assigned to a cache server.Duplication of cache contents is eliminated. Client requests to a cacheserver for non-assigned partition objects are forwarded to propersibling caches. As a result, the load level of the cache servers can bequite unbalanced. We examine an adaptable controlled replication (ACR)of non-assigned partition objects in each cache server to reduce theload imbalance and relieve the problem of hot-spot references.Trace-driven simulations are conducted to study the effectiveness ofACR. The results show that: (1) access skew exists, and the load of thecache servers tends to be unbalanced in hash routing; (2) with arelatively small amount of ACR, say 10% of the cache size, significantimprovements in load balance can be achieved; and (3) ACR provides avery effective remedy for load imbalance due to hot-spotreferences
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