OpenMosix, OpenSSI and Kerrighed: A Comparative Study

This paper presents a comparative study of Kerrighed, openMosix and OpenSSI, three Single System Image (SSI) operating systems for clusters. This experimental study gives an overview of SSI features offered by these SSI and evaluates performance of such features

Kerrighed: A SSI Cluster OS Running OpenMP

Writing parallel programs for clusters of workstations is still a challenging task. In this paper, we present Kerrighed, a Single System Image (SSI) operating system giving the illusion of an SMP machine, and providing the standard posix thread interface to developers. It is therefore possible to use Kerrighed to run OpenMP programs compiled for SMP-machines using the posix thread interface. In this paper, we explain how we managed to achieve that goal, and present the benefits of providing OpenMP support through the SSI approach as opposed to a dedicated run-time environment

Ghost Process: a Sound Basis to Implement Process Duplication, Migration and Checkpoint/Restart in Linux Clusters

Process management mechanisms (process duplication, migration and checkpoint/restart) are very useful for high performance and high availability in clustering systems. The single system image approach aims at providing a global process management service with mechanisms for process checkpoint, process migration and process duplication. In this context, a common mechanism for process virtualization is highly desirable but traditional operating systems do not provide such a mecahnism. This paper presents a kernel service for process virtualization called ghost process, extending the Linux kernel. The ghost process mechanism has been implemented in the Kerrighed single system image based on Linux. \\ Les mécanismes de gestion de processus (duplication, migration et création de point de reprise/reprise de processus) sont particulièrement intéressants pour les systèmes pour grappes de calculateurs à haute performance et à haute disponibilité. L'un des buts des systèmes à image unique est d'offrir un service de gestion globale des processus fondé sur des mécamismes de création de points de reprise de processus, de migration de processus et de duplication de processus. Dans ce contexte, un mécanisme commun pour la virtualisation de processus est hautement bénéfique mais les systèmes d'exploitation traditionnels n'offrent pas un tel mécanisme. Ce document présente un service noyau pour la virtualisation de processus, appelé processus fantôme, fondé sur une extension du noyau Linux. Le mécanisme de processus fantôme a été mis en oeuvre dans le système à image unique Kerrughed fondé sur Linux

A New Approach to Configurable Dynamic Scheduling in Clusters based on Single System Image Technologies

Clusters are now considered as an alternative to parallel machines to execute workloads made up of sequential and/or parallel applications. For efficient application execution on clusters, dynamic global process scheduling is of prime importance. Different dynamic scheduling policies that have been studied for distributed systems or parallel machines may be used in clusters. The choice of a particular policy depends on the kind of workload to be executed. In a cluster, it is thus highly desirable to implement a configurable global scheduler to be able to adapt the dynamic scheduling policy to the workload characteristics, to take benefit of all cluster resources and tocope with node shutdown and reboot. In this paper, we present the architecture of the global scheduler and the process management mechanisms of Kerrighed, a single system image operating system designed for high performance computing on clusters. Kerrighed provides a development framework allowing to easily implement dynamic scheduling policies without kernel modification. In Kerrighed, the global scheduling policy can be dynamically changed while applications execute on the cluster. Kerrighed's process management mechanisms allow to easily deploy parallelapplications in the cluster and to efficiently migrate or checkpoint processes, including processes sharing memory. Kerrighed has been implemented as a set of modules extending Linux kernel. Preliminary performance results are presented

Is Virtualization Killing Single System Image Research?

Nowadays, use of clusters in research centers or industries is undeniable. Cluster usage is typically based on two different models: (i) batch schedulers and (ii) single system image (SSI). In the first case, applications are scheduled by a ``supervisor'', the batch scheduler, according to cluster resources availability. In the second case, an SSI operating system (OS) gives the illusion that a distributed system is a standard SMP machine, allowing users to use standard UNIX tools to manage their applications. Even if SSI solutions are usually more complete in terms of functionality, batch schedulers are usually preferred because of their simplicity in term of both configuration and usage. Moreover, since few years, combining virtual machines and batch systems offer more advanced resource management capabilities, using features such as virtual machine live migration. Because of the latest contributions in the domain, some may argue that SSI technologies are now deprecated. In this paper, we analyze whether virtualization technologies will surpass the SSI approach, or if these two models are not contradictory but complementary. In fact, after evaluating different configurations, we show that by combining both approaches, we can improve several aspects associated to application computation such as flexibility of administration, simplicity of use, security and portability

A Framework for High Availability Based on a Single System Image

High availability (HA) is today an important issue in the domain of cluster computing, clusters being more and more larger, introducing a lot of failures. Today, the literature provides a lot of different HA strategies to tolerate application failures (applications being sequential or parallel). Unfortunately, it is still difficult to implement these HA policies inside a real system, and therefore the study of these policies is most of the time just theoretic, without real implementation. Therefore, a framework to ease the implementation of such policies is interesting. Moreover, a single system image (SSI), thanks to mechanisms for the global management of cluster resources, is a good candidate to provide such a framework. This paper presents the preliminary study of this framework on top of the Kerrighed SSI

Checkpointing and Recovery of Shared Memory Parallel Applications in a Cluster

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