Migration of processes, files, and virtual devices in the MDX operating system

Abstract

Load management in distributed systems is usually focused on balancing process execution and communication load. Stress on storage media and I/O-devices is considered only indirectly or disregarded. For I/O-intensive processes this imposes severe restrictions on balancing algorithms: processes have to be placed relative to fixed allocated resources. Therefore, beyond process migration, there is a need for a migration of all operating system objects, like files, pipes, timers, virtual terminals, and print jobs. In addition to new options for balancing cpu loads, this also makes it possible to balance the loads associated with these objects like storage capacity or I/O-bandwidth.This paper presents a concept for a general migration of nearly all operating system objects of a UNIX environment. The migrations of these objects work all in the same UNIX compliant and transparent manner. Objects can be moved throughout a distributed system independently of each other and at any time, according to a user defined policy. The migration mechanism is implemented as part of the MDX operating system; we present performance measurements. We believe that most of the mechanism can also apply to other message-passing based distributed operating systems.