Tamar Domany

Open job management architecture for the blue gene/l supercomputer

We describe an open job management architecture of the Blue Gene/L supercomputer. The architecture allows integration of virtually any job management system with Blue Gene/L with minimal effort. The architecture has several ”openness” characteristics. First, any job management system runs outside the Blue Gene/L core (i.e. no part of the job management system runs on Blue Gene/L resources). Second, the logic of the scheduling cycle (i.e. when to match jobs with resources) can be retained without modifications. Third, job management systems can use different scheduling and resources allocation models and algorithms. We describe the architecture, its main components, and its operation. We discuss in detail two job management systems, one based on LoadLeveler, the other — on SLURM, that have been successfully integrated with Blue Gene/L, independently of each other. Even though the two systems are very different, Blue Gene/Ls open job management architecture naturally accommodated both.

System management in the BlueGene/L supercomputer

The BlueGene/L supercomputer will use system-on-a-chip integration and a highly scalable cellular architecture to deliver 360 teraflops of peak computing power. With 65536 compute nodes, BlueGene/L represents a new level of scalability for parallel systems. As such, it is natural for many scalability challenges to arise. In this paper, we discuss system management and control, including machine booting, software installation, user account management, system monitoring, and job execution. We address the issue of scalability by organizing the system hierarchically. The 65536 compute nodes are organized in 1024 clusters of 64 compute nodes each, called processing sets. Each processing set is under control of a 65th node, called an I/O node. The 1024 processing sets can then be managed to a great extent as a regular Linux cluster, of which there are several successful examples. Regular cluster management is complemented by BlueGene/L specific services, performed by a service node over a separate control network. Our software development and experiments have been conducted so far using an architecturally accurate simulator of BlueGene/L, and we are gearing up to test real prototypes in 2003.

Multi-toroidal interconnects: using additional communication links to improve utilization of parallel computers

Three-dimensional torus is a common topology of network interconnects of multicomputers due to its simplicity and high scalability. A parallel job submitted to a three-dimensional toroidal machine typically requires an isolated, contiguous, rectangular partition connected as a mesh or a torus. Such partitioning leads to fragmentation and thus reduces resource utilization of the machines. In particular, toroidal partitions often require allocation of additional communication links to close the torus. If the links are treated as dedicated resources (due to the partition isolation requirement) this may prevent allocation of other partitions that could, otherwise, use those links. Overall, on toroidal machines, the likelihood of successful allocation of a new partition decreases as the number of toroidal partitions increases. This paper presents a novel ”multi-toroidal” interconnect topology that is able to accommodate multiple adjacent meshed and toroidal partitions at the same time. We prove that this topology allows connecting every free partition of the machine as a torus without affecting existing partitions. We also show that for toroidal jobs this interconnect topology increases machine utilization by a factor of 2 to 4 (depending on the workload) compared with three-dimensional toroidal machines. This effect exists for different scheduling policies. The BlueGene/L supercomputer being developed by IBM Research is an example of a multi-toroidal interconnect architecture.

Application-Screen Masking: A Hybrid Approach

Large organizations often face difficult tradeoffs in balancing the need to share information with the need to safeguard sensitive data. A prominent way to deal with this tradeoff is on-the-fly screen masking of sensitive data in applications. A proposed hybrid approach for masking Web application screens combines the advantages of the context available at the presentation layer with the flexibility and low overhead of masking at the network layer. This solution can identify sensitive information in the visual context of the application screen and then automatically generate the masking rules to enforce at run time. This approach supports the creation of highly expressive masking rules, while keeping rule authoring easy and intuitive, resulting in an easy to use, effective system. This article is part of a special issue on Security and Privacy on the Web. The Web extra at https://youtu.be/4u2FLqjaIiI is a short demonstration of a proposed hybrid approach for masking Web application screens that combines the advantages of the context available at the presentation layer with the flexibility and low overhead of masking at the network layer. The second Web extra at https://youtu.be/-Hz3P_H0UnU is a full-length demonstration of a proposed hybrid approach for masking Web application screens that combines the advantages of the context available at the presentation layer with the flexibility and low overhead of masking at the network layer.

Conceptual Framework and Architecture for Privacy Audit

Many ICT applications involve the collection of personal information or information on the behaviour of customers, users, employees, citizens, or patients. The organisations that collect this data need to manage the privacy of these individuals. In many organisations there are insufficient data protection measures and a low level of trust among those whose data are concerned. It is often difficult and burdensome for organisations to prove privacy compliance and accountability especially in situations that cross national boundaries and involve a number of different legal systems governing privacy. In response to these obstacles, we describe instruments facilitating accountability, audit, and meaningful certification. These instruments are based on a set of fundamentaldata protection goals DPG: availability, integrity, confidentiality, transparency, intervenability, and unlinkability. By using the data protection goals instead of focusing on fragmented national privacy regulations, a well defined set of privacy metrics can be identified recognising privacy by design requirements and widely accepted certification criteria. We also describe a novel conceptual framework and architecture for defining comprehensive privacy compliance metrics and providingassessment tools for ICT applications and services using as much automation as possible. The proposed metrics and tools will identify gaps, provide clear suggestions and will assist audit and certification to support informed decisions on the trustworthiness of ICT for citizens and businesses.