Browsing by Author "Wang, Hui"

Now showing 1 - 6 of 6
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    Balancing Fairness and Efficiency in Tiered Storage Systems using Bottleneck-Aware Allocation
    (USENIX: The Advanced Computing Systems Association, 2014-02) Varman, Peter J.; Wang, Hui
    Multi-tiered storage made up of heterogeneous devices are raising new challenges in allocating throughput fairly among concurrent clients. The fundamental problem is finding an appropriate balance between fairness to the clients and maximizing system utilization. In this paper we cast the problem within the broader framework of fair allocation for multiple resources. We present a new allocation model BAA based on the notion of per-device bottleneck sets. Clients bottlenecked on the same device receive throughputs in proportion to their fair shares, while allocation ratios between clients in different bottleneck sets are chosen to maximize system utilization. We show formally that BAA satisfies fairness properties of Envy Freedom and Sharing Incentive. We evaluated the performance of our method using both simulation and implementation on a Linux platform. The experimental results show that our method can provide both high efficiency and fairness.
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    Nanorice particles: hybrid plasmonic nanostructures
    (2010-09-07) Wang, Hui; Brandl, Daniel; Le, Fei; Nordlander, Peter J.; Halas, Nancy J.; Rice University; United States Patent and Trademark Office
    A new hybrid nanoparticle, i.e., a nanorice particle, which combines the intense local fields of nanorods with the highly tunable plasmon resonances of nanoshells, is described herein. This geometry possesses far greater structural tunability than previous nanoparticle geometries, along with much larger local field enhancements and far greater sensitivity as a surface plasmon resonance (SPR) nanosensor than presently known dielectric-conductive material nanostructures. In an embodiment, a nanoparticle comprises a prolate spheroid-shaped core having a first aspect ratio. The nanoparticle also comprises at least one conductive shell surrounding said prolate spheroid-shaped core. The nanoparticle has a surface plasmon resonance sensitivity of at least 600 nm RIU−1. Methods of making the disclosed nanorice particles are also described herein.
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    Nested QoS: Providing flexible SLAs in shared storage systems
    (2012) Wang, Hui; Varman, Peter J.
    The increasing popularity of storage and server consolidation introduces new challenges for resource management, capacity provisioning, and application performance guaranteeing. In addition, the bursty nature of storage workloads results in a large gap between the peak and the average capacity required to meet response time bounds, leading to low overall server utilization and high cost. This situation is driving the development of elastic QoS models that allow clients greater flexibility in adopting SLAs tailored to their workload characteristics and performance requirements, while allowing the service provider opportunities to optimize provisioning and scheduling decisions. This thesis presents a novel service model, called the Nested QoS model, for multiplexing concurrent bursty workloads in shared storage systems. The solution employs two strategies together: systematically classifying requests with a graduated QoS and flexibly scheduling the classified portions. The results show that the Nested QoS model provides (i) performance isolation and strong performance guarantees for both well-behaved and misbehaving workloads; (2) a flexible and auditable elastic SLA definition; and (3) improved server utilization.
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    Nonconcentric nanoshells with offset core in relation to shell and method of using the same
    (2012-05-15) Halas, Nancy J.; Wang, Hui; Nordlander, Peter J.; Wu, Yanpeng; Rice University; United States Patent and Trademark Office
    A nanoparticle comprising a shell surrounding a core material with a lower conductivity than the shell material, wherein the core center is offset in relation to the shell center. A method comprising providing a nanoparticle comprising a nonconductive core and a conductive shell, and asymmetrically depositing additional conductive material on the conductive shell. A method comprising providing a concentric nanoshell having a core and a shell, immobilizing the concentric nanoshell onto a support, and asymmetrically depositing a conductive material onto the shell to produce a nanoegg.
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    Resource Allocation Models for Multi-Tiered Storage: Balancing System Efficiency and QoS
    (2015-11-12) Wang, Hui; Varman, Peter J.; Cavallaro, Joseph R.; Zhong, Lin; Eugene Ng, T.S.
    Multi-tiered storage systems made up of combined Solid State Drives (SSDs) and Hard Disks (HDs) are becoming increasingly popular in shared data centers due to their favorable cost and performance characteristics. Meantime, they are raising new challenges in allocating resources efficiently and providing Quality of Service (QoS) guarantees. Traditional proportional sharing or its generalizations are designed to provide QoS for a single resource type, and lead to poor system utilization when applied to multiple coupled resources. In this thesis we cast the problem of managing multi-tiered storage systems within the broader framework of resource allocation for multiple resources. A fundamental problem that arises when jointly allocating multiple resources is to define fairness policies that provide meaningful QoS guarantees while simultaneously ensuring that system resources are well utilized. We propose a model called Bottleneck-Aware Allocation (BAA), which provides a new definition of fairness for allocation of multiple resources.Based on this notion of per-device bottleneck sets, we design a computationally-effi cient algorithm that maximizes system utilization while meeting re-source capacity constraints and client fairness properties. We show formally that BAA satisfies fairness properties of Envy Freedom and Sharing Incentive. Secondly, we propose a model called Multi-Resource Allocation (MRA), which provides strong quantitative QoS controls including reservations and shares to each client. Reservations specify the minimum throughput (IOPS) that a client must receive, while shares reflect its weight relative to other clients that are bottlenecked on the same device. IOPS based allocation does not differentiate between types of IO requests. This motivates the use of time-based allocation, which considers the variation in request service times. We present Time-Based Bandwidth Allocation (TBBA) to fairly time-multiplex a hybrid storage system while maximizing system throughput. A new allocation model and scheduling are also described.
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    Tunable plasmonic nanostructures: From fundamental nanoscale optics to surface-enhanced spectroscopies
    (2008) Wang, Hui; Halas, Naomi J.
    In this thesis, I demonstrate the rational design and controllable fabrication of a series of novel plasmonic nanostructures with judiciously tailored optical properties including perfect nanoshells, roughened subwavelength particles, prolate nanoshells known as nanorice, and non-concentric nanoshells known as nanoeggs. All of these nanostructures are very important subwavelength nanoscale optical components that can be utilized to manipulate light in unique ways. The most striking feature of these nanoparticles is their geometrically tunable plasmon resonances, which can be harnessed for widespread applications. I have also utilized these nanostructures as the building blocks to construct self-assembled multinanoparticle systems, such as nanoshell heterodimers, nanosphere arrays and nanoshell arrays. I have further developed multifunctional molecular sensing platforms using these nanoengineered plasmonic structures as substrates for surface-enhanced spectroscopies, realizing integrated analytical chemistry lab-on-a-chip. Applying the Plasmon Hybridization model as design principles to experimentally realizable nanostructures results in a thorough understanding of the origin of the geometry-dependent optical properties observed in these nanosystems. Finite Difference Time Domain (FDTD) method also provides a powerful platform for the numerical simulation of local- and far-field optical properties of these nanostructures.