Designing, implementing and evaluating a Grid operating system in open source with native support for Virtual Organizations (VO) 

The expected main achievement will be a Grid OS made up of a set of system services based on the Linux general-purpose OS, extended to support VO and to provide appropriate interfaces to the Grid OS services.

The main objectives of the XtreemOS project are:

• To build a reference open source Grid operating system based on Linux for PCs, clusters and mobile devices;

• To provide a simple Grid API compliant with POSIX while adding new functionalities and supporting Grid-aware applications;

• To identify fundamental functionalities to be embedded in Linux for secure application execution in Grid environments;

• To develop a set of self-healing OS services for secure resource management in very large dynamic grids;

• To aggregate cluster resources into powerful Grid nodes by integrating single system image mechanisms in Linux;

• To build an XtreemOS flavour for mobile devices enabling ubiquitous access to Grid resources;

• To validate the design and implementation of the XtreemOS Grid operating system with a set of real use cases in scientific and business domains on a large Grid testbed;

• To promote XtreemOS software and create communities of users and developers.

The key technological challenges in XtreemOS, compared to the classical middleware (“à la Globus”) approaches, are mainly related to the fact that XtreemOS aims to be a first step towards the creation of a “true” open source operating system for Grid platforms supporting distributed resources, such as PCs and mobile devices like PDAs or mobile phones. It is just as a traditional operating system does for a single computer providing an abstract interface to its underlying local physical resources.

While much work has been done to build Grid middleware on top of existent operating systems, little has been done to extend the underlying operating systems for enabling and facilitating Grid computing, for example, by embedding some important basic services or functionalities directly into the operating system kernel.

The “à la Globus” approaches are designed as a “sum of services” infrastructure, in which tools are developed independently in response to current needs of users. In particular, Globus started out with the bottom-up premise that a Grid must be constructed as a set of tools developed from user requirements, and consequently its versions (GT2, GT3, GT4) are based on the combination of working components into a composite Grid toolkit that fully exposes the Grid to the programmer. However, a risk associated with those approaches is that, as the number of services grows, the lack of a common programming interface to components and the lack of a unifying model of their interaction can have a negative impact on ease of use. Typically, these issues must be dealt with by the programmer, who is forced to spend valuable time on basic Grid functions (e.g. providing their own mechanisms for service interoperability), thus needlessly increasing development time and costs.

At XtreemOS, we believe that the Grid infrastructure must absolutely reduce the burden on the application developer investing on the open source operating systems and extending them towards Grid, simplifying the life of the high-level Grid services implementers because they could rely on the native services of the operating system kernel for tasks such as resource or process management.

One of the first and the most important challenges in XtreemOS is the identification of the fundamental functionalities that are to be embedded and the selection of an existing operating system able to be modified at the kernel-level. For the latter choice, Linux provides an excellent basis because:
- its source code is readily available,
- it is a complete OS, and
- it is written in C, which makes it easy to modify.

In order to transform Linux to a distributed OS, a number of components will have to be added and integrated into the existing structure.

The approach we propose to investigate in XtreemOS is not only the construction and the distribution of an open-source Grid OS but also to validate its design and its implementation through a set of real use cases, given by well-known industrial partners, that covers a large spectrum of applications fields (aerospace, energy, telecom, business, multimedia, computer graphics, finance).