Efficient Memory Page Replacement on Web Server Clusters
ICCS '02 Proceedings of the International Conference on Computational Science-Part III
Vertical Data Migration in Large Near-Line Document Archives Based on Markov-Chain Predictions
VLDB '97 Proceedings of the 23rd International Conference on Very Large Data Bases
Integrated document caching and prefetching in storage hierarchies based on Markov-chain predictions
The VLDB Journal — The International Journal on Very Large Data Bases
| Hi-index | 0.00 |
Popular web sites are already experiencing very heavy loads, and these loads will only increase as the number of users accessing them grows. These loads create both CPU and I/O bottlenecks. One promising solution already being employed to eliminate the CPU bottleneck is to replace a single processor server with a cluster of servers. Our goal in this paper is to develop buffer management algorithms that exploit the aggregate memory capacity of the machines in such a server cluster to attack the I/O bottleneck. The key challenge in designing such buffer management algorithms turns out to be controlling data replication so as to achieve a good balance between intra-cluster network traffic and disk I/O. At one extreme, the straightforward application of client-server memory management techniques to this cluster architecture causes duplication in memory among the servers and this tends to reduce network traffic but increases disk I/O, whereas at the other extreme, eliminating all duplicates tends to increase network traffic while reducing disk I/O. Accordingly, we present a new algorithm, Hybrid, that dynamically controls the amount of duplication. Through a detailed simulation, we show that on workloads characteristic of those experienced by Web servers, the Hybrid algorithm correctly trades off intra-cluster network traffic and disk I/O to minimize average response time.