Designing a job management system for the Grid is a non-trivial task. While a complex middleware can give a lot of features, it often implies sacrificing performance. Such performance loss is especially noticeable for small jobs. A Job Manager's design also affects the capabilities of the monitoring system. We believe that monitoring a job or asking for a job status should be fast and easy, like doing a simple 'ps'. In this paper, we present the job management of XtreemOS - a Linux-based operating system to support Virtual Organizations for Grid. This management is performed inside the Application Execution Manager (AEM). We evaluate its performance using only one job manager plus the built-in monitoring infrastructure. Furthermore, we present a set of real-world applications using AEM and its features. In XtreemOS we avoid reinventing the wheel and use the Linux paradigm as an abstraction. Keywords: Grid Middleware, Monitoring, XtreemOS, Scalability