NFSv4 migration: Implementation Experience and Specification Issues

The migration feature of NFSv4 provides for moving responsibility for a single filesystem from one server to another, without disruption to clients. Recent implementation experience has shown problems in the existing specification for this feature. This document discusses options to cure issues which have arisen. It also explains the choices made in updating the NFSv4.0 specification and those to be made with regard to the NFSv4.1 specification, in order to properly address migration.