this book constitutes the refereed proceedings of the 19th ifip/ieee international workshop on distributed systems: operations and management, dsom 2008, held on samos island, greece, on september 22-26, 2008, as part of the 4th international week on management of networks and services, manweek 2008. the 14 revised full papers presented were carefully reviewed and selected from 38 submissions. the papers are organized in topical sections on decentralized and peer-to-peer management; operations and tools; security and trust; and measurements, monitoring and diagnosis.