The workstation file system for the Cedar programming environment was modified to improve its robustness and performance. Previously, the file system used hardware-provided labels on disk blocks to increase robustness against hardware and software errors. The new system does not require hardware disk labels, yet is more robust than the old system. Recovery is rapid after a crash. The performance of operations on file system metadata, e.g., file creation or open, is greatly improved.

Database systems normally have been designed with the assumption that main memory is too small to hold the entire database. With the decreasing cost and increasing performance of semiconductor memories, future database systems may be constructed that keep most or all of the data for the database in main memory. The challenge in the design of these systems is to provide fast transaction processing, to effectively use multiple processors, and to perform a fast restart after a crash. This correspondence presents a method of performing crash recovery for these systems.

The growing acceptance of database systems makes their performance increasingly more important. One way to gain performance is to off-load some of the functions of the database system to aback-end computer. The problem is what functions should be off-loaded to maximize the benefits of distributed processing. Our approach to this problem consisted of constructing several variants of an existing relational database system. INGRES, that partition the database system software into two parts, and assigning these two parts to two computers connected by a local area network. For the purposes of this experiment, six different variants of the database software were constructed to test the sir most interesting functional subdivisions. Each variant was then benchmarked using two different databases and query streams. The communication medium and the communication software were also benchmarked to measure their contribution to the performance of each configuration. Combining the database and network measurement results, various conclusions were reached about the viability of the configurations, the desirable properties of the communications mechanisms to he used, the operating system interface and overhead, and the performance of the database system. The variants to be preferred depend on the hardware technology, operating system features, database system internal structure, and network software overhead.