Autonomous disks for advanced database applications

The scalability and reliability of secondary storage systems are their most significant aspects for advanced database applications. Research on high-function disks has recently attracted a great deal of attention because technological progress now allows disk-resident data processing. This capability is not only useful for executing application programs on the disk, but is also suited for controlling distributed disks so they are scalable and reliable. We propose autonomous disks in the network environment by using the disk-resident data processing facility. A set of autonomous disks is configured as a cluster in a network, and data is distributed within the cluster, to be accessed uniformly by using a distributed directory. The disks accept simultaneous accesses from multiple hosts via a network, and handle data distribution and load skews. They are also able to tolerate disk failures and some software errors of disk controllers, and can reconfigure the cluster after the damaged disks are repaired. The data distribution, skew handling, and fault tolerance are completely transparent to hosts. The local communication means the size of the cluster is scalable. Autonomous disks are applicable to many advanced applications, such as a large Web server having many HTML files. We also propose to use rules to implement these functions, and we demonstrate their flexibility by examples of rules.