An implementation of disk objects in the logical machine monitor

User or program mobility in distributed computing systems is becoming increasingly significant, since users may sometimes change their working locations. This paper proposes a Logical Machine (LM) system that can effectively support software environment migration and resource mapping. The LM partitions the conventional operating systems into two parts: the Logical Machine Operating System (LMOS) and the Logical Machine Monitor (LMM). They are responsible for user service and system resource management, respectively. The LMM provides a machine independent appearance, called the Logical Machine Interface (LMI), for the upper operating system layers to provide the resources they need. In our experimental system, the LMM contains some disk objects that can be bound dynamically. By varying the binds, the users get different disk characteristics. A mobile disk object with the mechanism of block migration on demand is implemented. It can be incorporated with a logical machine migration facility to achieve job migration, i.e., the user can migrate the operating system and disk blocks to the place he or she desires. The mobile disk also simplifies the mechanism of parallel processing when each server reads and processes its data portion locally. With this approach, the system resources can be mapped more flexibly, while transparency to the operating system is retained. © 1997 John Wiley & Sons, Ltd.