High performance and reliable disk and basic file services for the distributed environment of RHODOS

We demonstrate that the typical problem of loss in performance due to disk I/O can be efficiently dealt with by using separate strategies for the storage of file data and data structures required for file management. Furthermore, to make the design very reliable, stable storage is provided. In fact the design is reliable to the extent that even after all types of hardware and software failures (except the most catastrophic ones, e.g., all the hard disks crashing at a time) the system can retrieve the file´s data. In order to further improve performance the design of the caching module takes into consideration all the aspects of the basic file and transaction services. The design of the disk service allows the contents of a file to be distributed among more than one disk drive. Thus, for all practical purposes the design imposes virtually no restrictions on the file size and disk capacity