6,551 research outputs found
Checkpointing in hybrid distributed systems
2003-2004 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe
CHECKPOINTING AND RECOVERY IN DISTRIBUTED AND DATABASE SYSTEMS
A transaction-consistent global checkpoint of a database records a state of the database which reflects the effect of only completed transactions and not the re- sults of any partially executed transactions. This thesis establishes the necessary and sufficient conditions for a checkpoint of a data item (or the checkpoints of a set of data items) to be part of a transaction-consistent global checkpoint of the database. This result would be useful for constructing transaction-consistent global checkpoints incrementally from the checkpoints of each individual data item of a database. By applying this condition, we can start from any useful checkpoint of any data item and then incrementally add checkpoints of other data items until we get a transaction- consistent global checkpoint of the database. This result can also help in designing non-intrusive checkpointing protocols for database systems. Based on the intuition gained from the development of the necessary and sufficient conditions, we also de- veloped a non-intrusive low-overhead checkpointing protocol for distributed database systems.
Checkpointing and rollback recovery are also established techniques for achiev- ing fault-tolerance in distributed systems. Communication-induced checkpointing algorithms allow processes involved in a distributed computation take checkpoints independently while at the same time force processes to take additional checkpoints to make each checkpoint to be part of a consistent global checkpoint. This thesis develops a low-overhead communication-induced checkpointing protocol and presents a performance evaluation of the protocol
A Recovery Scheme for Cluster Federations Using Sender-based Message Logging
A cluster federation is a union of clusters and is heterogeneous. Each cluster contains a certain number of processes. An application running in such a computing environment is divided into communicating modules so that these modules can run on different clusters. To achieve fault-tolerance different clusters may employ different check pointing schemes. For example, some may use coordinated schemes, while some other may use communication-induced schemes. It may complicate the recovery process. In this paper, we have addressed the complex problem of recovery for cluster computing environment. The proposed approach handles both inter cluster orphan and lost messages unlike the existing works in this area. We first propose an algorithm to determine a recovery line so that there does not exist any inter cluster orphan message between any pair of the cluster level check points belonging to the recovery line. The main feature of the proposed algorithm is that it can be executed simultaneously by all clusters in the cluster federation. Next we apply the sender-based message logging idea to effectively handle all inter cluster lost messages to ensure correctness of computation
Many-Task Computing and Blue Waters
This report discusses many-task computing (MTC) generically and in the
context of the proposed Blue Waters systems, which is planned to be the largest
NSF-funded supercomputer when it begins production use in 2012. The aim of this
report is to inform the BW project about MTC, including understanding aspects
of MTC applications that can be used to characterize the domain and
understanding the implications of these aspects to middleware and policies.
Many MTC applications do not neatly fit the stereotypes of high-performance
computing (HPC) or high-throughput computing (HTC) applications. Like HTC
applications, by definition MTC applications are structured as graphs of
discrete tasks, with explicit input and output dependencies forming the graph
edges. However, MTC applications have significant features that distinguish
them from typical HTC applications. In particular, different engineering
constraints for hardware and software must be met in order to support these
applications. HTC applications have traditionally run on platforms such as
grids and clusters, through either workflow systems or parallel programming
systems. MTC applications, in contrast, will often demand a short time to
solution, may be communication intensive or data intensive, and may comprise
very short tasks. Therefore, hardware and software for MTC must be engineered
to support the additional communication and I/O and must minimize task dispatch
overheads. The hardware of large-scale HPC systems, with its high degree of
parallelism and support for intensive communication, is well suited for MTC
applications. However, HPC systems often lack a dynamic resource-provisioning
feature, are not ideal for task communication via the file system, and have an
I/O system that is not optimized for MTC-style applications. Hence, additional
software support is likely to be required to gain full benefit from the HPC
hardware
Application-level Fault Tolerance and Resilience in HPC Applications
Programa Oficial de Doutoramento en Investigación en Tecnoloxías da Información. 524V01[Resumo]
As necesidades computacionais das distintas ramas da ciencia medraron enormemente
nos últimos anos, o que provocou un gran crecemento no rendemento proporcionado
polos supercomputadores. Cada vez constrúense sistemas de computación
de altas prestacións de maior tamaño, con máis recursos hardware de distintos tipos,
o que fai que as taxas de fallo destes sistemas tamén medren. Polo tanto, o
estudo de técnicas de tolerancia a fallos eficientes é indispensábel para garantires
que os programas científicos poidan completar a súa execución, evitando ademais
que se dispare o consumo de enerxía. O checkpoint/restart é unha das técnicas máis
populares. Sen embargo, a maioría da investigación levada a cabo nas últimas décadas
céntrase en estratexias stop-and-restart para aplicacións de memoria distribuída
tralo acontecemento dun fallo-parada. Esta tese propón técnicas checkpoint/restart
a nivel de aplicación para os modelos de programación paralela roáis populares en
supercomputación. Implementáronse protocolos de checkpointing para aplicacións
híbridas MPI-OpenMP e aplicacións heteroxéneas baseadas en OpenCL, en ámbolos
dous casos prestando especial coidado á portabilidade e maleabilidade da solución.
En canto a aplicacións de memoria distribuída, proponse unha solución de resiliencia
que pode ser empregada de forma xenérica en aplicacións MPI SPMD, permitindo
detectar e reaccionar a fallos-parada sen abortar a execución. Neste caso, os procesos
fallidos vólvense a lanzar e o estado da aplicación recupérase cunha volta atrás global.
A maiores, esta solución de resiliencia optimizouse implementando unha volta
atrás local, na que só os procesos fallidos volven atrás, empregando un protocolo de
almacenaxe de mensaxes para garantires a consistencia e o progreso da execución.
Por último, propónse a extensión dunha librería de checkpointing para facilitares a implementación de estratexias de recuperación ad hoc ante conupcións de memoria.
En moitas ocasións, estos erros poden ser xestionados a nivel de aplicación, evitando
desencadear un fallo-parada e permitindo unha recuperación máis eficiente.[Resumen]
El rápido aumento de las necesidades de cómputo de distintas ramas de la ciencia
ha provocado un gran crecimiento en el rendimiento ofrecido por los supercomputadores.
Cada vez se construyen sistemas de computación de altas prestaciones mayores,
con más recursos hardware de distintos tipos, lo que hace que las tasas de
fallo del sistema aumenten. Por tanto, el estudio de técnicas de tolerancia a fallos
eficientes resulta indispensable para garantizar que los programas científicos puedan
completar su ejecución, evitando además que se dispare el consumo de energía. La
técnica checkpoint/restart es una de las más populares. Sin embargo, la mayor parte
de la investigación en este campo se ha centrado en estrategias stop-and-restart
para aplicaciones de memoria distribuida tras la ocurrencia de fallos-parada. Esta
tesis propone técnicas checkpoint/restart a nivel de aplicación para los modelos de
programación paralela más populares en supercomputación. Se han implementado
protocolos de checkpointing para aplicaciones híbridas MPI-OpenMP y aplicaciones
heterogéneas basadas en OpenCL, prestando en ambos casos especial atención a la
portabilidad y la maleabilidad de la solución. Con respecto a aplicaciones de memoria
distribuida, se propone una solución de resiliencia que puede ser usada de forma
genérica en aplicaciones MPI SPMD, permitiendo detectar y reaccionar a fallosparada
sin abortar la ejecución. En su lugar, se vuelven a lanzar los procesos fallidos
y se recupera el estado de la aplicación con una vuelta atrás global. A mayores, esta
solución de resiliencia ha sido optimizada implementando una vuelta atrás local, en
la que solo los procesos fallidos vuelven atrás, empleando un protocolo de almacenaje
de mensajes para garantizar la consistencia y el progreso de la ejecución. Por
último, se propone una extensión de una librería de checkpointing para facilitar la
implementación de estrategias de recuperación ad hoc ante corrupciones de memoria.
Muchas veces, este tipo de errores puede gestionarse a nivel de aplicación, evitando
desencadenar un fallo-parada y permitiendo una recuperación más eficiente.[Abstract]
The rapid increase in the computational demands of science has lead to a pronounced
growth in the performance offered by supercomputers. As High Performance
Computing (HPC) systems grow larger, including more hardware components
of different types, the system's failure rate becomes higher. Efficient fault
tolerance techniques are essential not only to ensure the execution completion but
also to save energy. Checkpoint/restart is one of the most popular fault tolerance
techniques. However, most of the research in this field is focused on stop-and-restart
strategies for distributed-memory applications in the event of fail-stop failures. Thís
thesis focuses on the implementation of application-level checkpoint/restart solutions
for the most popular parallel programming models used in HPC. Hence, we
have implemented checkpointing solutions to cope with fail-stop failures in hybrid
MPI-OpenMP applications and OpenCL-based programs. Both strategies maximize
the restart portability and malleability, ie., the recovery can take place on
machines with different CPU / accelerator architectures, and/ or operating systems,
and can be adapted to the available resources (number of cores/accelerators). Regarding
distributed-memory applications, we propose a resilience solution that can
be generally applied to SPMD MPI programs. Resilient applications can detect and
react to failures without aborting their execution upon fail-stop failures. Instead,
failed processes are re-spawned, and the application state is recovered through a
global rollback. Moreover, we have optimized this resilience proposal by implementing
a local rollback protocol, in which only failed processes rollback to a previous
state, while message logging enables global consistency and further progress of the
computation. Finally, we have extended a checkpointing library to facilitate the
implementation of ad hoc recovery strategies in the event of soft errors) caused by
memory corruptions. Many times, these errors can be handled at the software-Ievel,
tIms, avoiding fail-stop failures and enabling a more efficient recovery
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