Subu Iyer

SLA Decomposition: Translating Service Level Objectives to System Level Thresholds

In todays complex and highly dynamic computing environments, systems/services have to be constantly adjusted to meet service level agreements (SLAs) and to improve resource utilization, thus reducing operating cost. Traditional design of such systems usually involves domain experts who implicitly translate service level objectives (SLOs) specified in SLAs to system-level thresholds in an ad-hoc manner. In this paper, we present an approach that combines performance modeling with performance profiling to create models that translate SLOs to lower-level resource requirements for each system involved in providing the service. Using these models, the process of creating an efficient design of a system/service can be automated, eliminating the involvement of domain experts. We demonstrate that our approach is practical and that it can be applied to different applications and software architectures. Our experiments show that for a typical 3-tier e-commerce application in a virtualized environment the SLAs can be met while improving CPU utilization up to 3 times.

First steps towards mutually-immersive mobile telepresence

Mutually-Immersive Mobile Telepresence uses a teleoperated robotic surrogate to visit remote locations as a substitute for physical travel. Our goal is to recreate to the greatest extent possible, both for the user and the people at the remote location, the sensory experience relevant for business interactions of the user actually being in the remote location. The system includes multi-channel bidirectional video and audio on a mobile platform as well as haptic feedback. This paper describes our first system prototypes and initial experiences using them.

BiReality: mutually-immersive telepresence

BiReality (a.k.a. Mutually-Immersive Telepresence) uses a teleoperated robotic surrogate to provide an immersive telepresence system for face-to-face interactions. Our goal is to recreate to the greatest extent practical, both for the user and the people at the remote location, the sensory experience relevant for face-to-face interactions of the user actually being in the remote location. Our system provides a 360-degree surround immersive audio and visual experience for both the user and remote participants, and streams eight 704x480 MPEG-2 coded videos totaling 20Mb/s. The system preserves gaze and eye contact, presents local and remote participants to each other at life size, and preserves the head height of the user at the remote location. Initial user experiences are presented.

A state-space approach to SLA based management

Large complex systems (such as Enterprise systems) are often composed of several interacting, independent components. In many such systems, although the behavior of the constituent components is well characterized, the behavior that results from interaction between such components is more or less intractable; making it hard for the administrators to efficiently manage the system in conformance with the service level agreements or the SLAs. This paper presents an approach for deriving component-level objectives from system-level objectives or agreements, which if conformed to, imply conformance to the higher-level SLA. Our approach partitions the systempsilas state-space into homogeneous sub-spaces, creates micro-models for such subspaces, and then uses such micro-models to translate the higher-level objectives to component-level objectives. We have implemented a system, termed Pranaali, for evaluating our approach in realistic settings.

Translating Service Level Objectives to lower level policies for multi-tier services

Service providers and their customers agree on certain quality of service guarantees through Service Level Agreements (SLA). An SLA contains one or more Service Level Objectives (SLO)s that describe the agreed-upon quality requirements at the service level. Translating these SLOs into lower-level policies that can then be used for design and monitoring purposes is a difficult problem. Usually domain experts are involved in this translation that often necessitates application of domain knowledge to this problem. In this article, we propose an approach that combines performance modeling with regression analysis to solve this problem. We demonstrate that our approach is practical and that it can be applied to different n-tier services. Our experiments show that for a typical 3-tier e-commerce application in a virtualized environment, the SLA can be met while improving CPU utilization by up to 3 times.

Moara: flexible and scalable group-based querying system

Users and administrators of large-scale infrastructures (e.g., datacenters and PlanetLab) are frequently in need of monitoring groups of machines in the infrastructure. Though there exist several distributed querying systems for this monitoring purpose, they are not group-based; they mostly focus on querying the entire system. In this paper, we present Moara, a new querying system that makes two novel contributions. First, Moara builds aggregation trees for different groups and adaptively maintains the trees to optimize the total message cost. Second, Moara supports a query language allowing groups to be specified implicitly via predicates consisting of arbitrarily nested unions and intersections. Our evaluations on Emulab, on PlanetLab, and with large-scale simulations, demonstrate Moaras ability to answer complex queries within a fraction of a second, to deal with high levels of dynamism in groups, and to incur a low bandwidth overhead per host per query in comparison to existing centralized and distributed aggregation systems.

Dealing with scale and adaptation of global Web services management

Service oriented architectures (SOA) are becoming the prevalent approach for realizing modern services and systems. SOA offers superior support for autonomy (decoupling) and heterogeneity compared to previous generation middleware systems, resulting in more scalable and adaptive solutions. However, SOA have not adequately addressed management, while traditional management solutions do not sufficiently scale to address the needs of (global) Web services. We propose scalable management based on models and industry standards. We discuss a use case for global service management, we present its design, implementation and preliminary evaluation. We retain all the benefits of SOA while also enabling global scale manageability. Our approach provides manageability that is comprehensible for administrators yet automated enough for integration into autonomous systems.

A systematic and practical approach to generating policies from service level objectives

In order to manage a service to meet the agreed upon SLA, it is important to design a service of the required capacity and to monitor the service thereafter for violations at runtime. This objective can be achieved by translating SLOs specified in the SLA into lower-level policies that can then be used for design and enforcement purposes. Such design and operational policies are often constraints on thresholds of lower level metrics. In this paper, we propose a systematic and practical approach that combines fine-grained performance modeling with regression analysis to translate service level objectives into design and operational policies for multi-tier applications. We demonstrate that our approach can handle both request-based and session-based workloads and deal with workload changes in terms of both request volume and transaction mix. We validate our approach using both the RUBiS e-commerce benchmark and a trace-driven simulation of a business-critical enterprise application. These results show the effectiveness of our approach.

Dealing with Scale and Adaptation of Global Web Services Management

Service Oriented Architectures (SOA) are becoming the prevalent approach for realizing modern services and systems. SOA offers superior support for autonomy (decoupling) and heterogeneity compared to previous generation middleware systems, resulting in more scalable and adaptive solutions. However, SOA have not adequately addressed management, while traditional management solutions do not sufficiently scale to address the needs of (global) Web services. We propose scalable management based on models and industry standards. We discuss a use case for global service management and present its design, implementation, and preliminary evaluation. We retain all the benefits of SOA while also enabling global scale manageability. Our approach provides manageability that is comprehensible for administrators yet automated enough for integration into autonomous systems.

A first generation Mutually-Immersive Mobile Telepresence surrogate with automatic backtracking

Mutually-immersive mobile telepresence uses a teleoperated robotic surrogate to visit remote locations as a substitute for physical travel. Our goal is to recreate to the greatest extent practical, both for the user and the people at the remote location, the sensory experience relevant for business interactions of the user actually being in the remote location. The system includes multi-channel bidirectional video and audio on a mobile platform as well as haptic feedback. The user-controlled surrogate can autonomously backtrack along the path it has previously been driven if it loses wireless connectivity.