This document comprises the final report on the IST Integrated Project XtreemOS - "Building and promotinga Linux-based operating systems to support virtual organizations for next generation Grids".The project started in June 2006 and ended in September 2010.The XtreemOS operating system provides for Grids what a traditional operating system offers fora single computer: abstraction from the hardware and secure resource sharing between different users.It thus simplifies the work of users belonging to virtual organizations by giving them the illusion ofusing a traditional computer while removing the burden of complex resource management issues of atypical Grid environment.We have developed a comprehensive set of cooperating system services. XtreemOS softwarecomponents range from Linux kernel modules to application-support libraries. The XtreemOS operatingsystem provides three major distributed services to users: application execution management(providing scalable resource discovery and job scheduling for distributed interactive applications),data management (accessing and storing data in XtreemFS, a POSIX-like file system spanning theGrid) and virtual organization management (building and operating dynamic virtual organizations).Three flavours of the system have been implemented for individual PC, clusters and mobile devices(PDA, smartphone, notebook).The XtreemOS software has been experimented and validated with a wide range of applications.Various demonstrators were implemented, shown at different events and published on the web.The project results are available as open source software. The consortium member organizationsplan to exploit some of the results in follow-up research projects and in future products.1
