Virtual Storage Device Research Articles

Modelling of Consumption Shares for Small Wind Energy Prosumers

This article describes a simulation of energy distribution in an average household where electricity is produced with a small wind generator or purchased from the public electricity grid. Numerical experiments conducted within an average of five minutes were performed using annual production and consumption graphs. Virtual storage devices, a water tank and a battery were used to buffer energy inside the household. The energy required for non-shiftable consumption and hot water consumption were taken directly from the utility grid. Surplus energy remaining from wind generator production after providing for consumption and storage needs were redirected there. A cover factor was used as a measure of the efficiency of energy distribution. One of the aims of the article was to determine by simulations the change of the cover factor in a virtually designed situation where the expected energy output of the wind generator was known in advance over one to three hours. The results found that for the configuration of the proposed nanogrid option, the positive results were readily achieved when the expected wind generator production was known an hour ahead. Then, the cover factor increased from 0.593 to 0.645. The side result of using projected/expected production is an increase in asymmetrical energy exchanges bilaterally between nanogrid and utility grid in favour of grid sales. Another finding was that the cover factor depended on the wind generator’s production intensity but less on the intensity of consumption within the household.It is hoped/expected that future research will address the prediction of output using mathematical methods.

Virtual Storage Plant Aggregating Electrical Energy Storages and HVAC Systems Providing Regulating Reserve and Voltage Regulation

Abstract This paper presents a distributed predictive control framework coordinating battery energy storage systems and Heating, Ventilation and Air Conditioning (HVAC) systems in the distribution network for the provision of ancillary services to the power grid, whilst keeping both the indoor thermal comfort and the network voltage within acceptable limits. The HVAC systems are modeled as virtual storage devices and aggregated with battery energy storage systems to form virtual storage plants (VSPs). An optimization problem over a given prediction horizon is formulated for coordinating an arbitrary number of such VSPs so as to deliver the required regulation reserve whilst maintaining an acceptable voltage profile of the distribution network. The formulated optimization problem is incorporated into a Model Predictive Control (MPC) scheme. The nonlinear HVAC system model makes the resulted MPC problem nonlinear, which is then convexified and solved in a distributed manner by using the alternating direction method of multipliers (ADMM). Simulation results using realistic data demonstrate the effectiveness of the proposed approach, which delivers the required services by satisfying the system constraints.

Experimental evaluation of the performance of virtual storage units in hybrid micro grids

The work presented in this article proposes a new energy management algorithm for hybrid micro grids consisting of higher penetration of DC non-critical (NC) loads and renewable energy sources. The methodology suggested in this work is a rule based approach and tries to make the micro grids more autonomous. During generation deficits in the micro grids, the suggested control strategy proposes to make the hybrid micro grids self-dependent to a possible extent, without the incorporation of actual storage devices. Instead of using actual storage elements like the batteries or super capacitors, the projected approach uses virtual storage devices, like the DC electric springs for its functionality. The electric springs used in this work operate the DC NC loads in accordance with the voltage produced by the renewable sources, which in turn reduces the power import from the main grid during generation deficits in the micro grid. Further, the work presented in the due course only studies about the efficiency of the proposed algorithm by operating the DC NC loads as per the requirement, without intervening with the AC and DC critical loads operation. In order to test the robustness of the proposed methodology a scaled down hybrid micro grid is developed in the laboratory using dSPACE 1104 real time interface.

Virtual Storage Queue Handling in Cloud Computing

In cloud computing with host virtualization, it is necessary to understand the queue of storage for disk requests due to the competition for the storage requirements of Virtual Machine (VM). In this paper, we address schemes, sequence and dynamic balance allocation, for handling the VM queue to access the virtual storage device. SimPy, python-based simulation tool, is adopted to build the simulation models to get analytical data. The SimPy simulator incorporates the resource analyzing.

Trusted Storage Virtualization in Cloud Computing

The IaaS cloud computing is utilized by companies to gain benefits in reducing their IT expenses and overhead. However, in reality, it is rarely done because of security concerns, especially storage security of insider attacks. To reduce the risk of insider attacks, this paper presents a trusted Virtual Block Store (tVBS) architecture in IaaS cloud computing based on virtualization and Trusted Computing technologies. The core component of the tVBS is the trusted virtual block device, which can be automatic deployed and be attested by customers. The tVBS makes the virtual block storage device like a trusted physical block device to customers and extends host TPM trust into the computing environments within all virtual block devices. We also have implemented a prototype of the tVBS architecture based on the Xen hypervisor.

Making use of cloud computing for healthcare provision: Opportunities and challenges

Cloud or utility computing is an emerging new computing paradigm designed to deliver numerous computing services through networked media such as the Web. This approach offers several advantages to potential users such as “metered” use (i.e., pay-as-you-go) which offers scalability, online delivery of software and virtual hardware services (e.g., collaboration programmes, virtual servers, virtual storage devices) which would enable organizations to obviate the need to own, maintain and update their software and hardware infrastructures. The flexibility of this emerging computing service has opened many possibilities for organizations that did not exist before. Among those organizations are those engaged in healthcare provision. The aim of this article is to shed some light on this development and explore the potential (and future) of cloud computing in contributing to the advancement of healthcare provision. A small case study will also be presented and discussed.

Optimizing Storage Performance for VM-Based Mobile Computing

This article investigates the transient use of free local storage for improving performance in VM-based mobile computing systems implemented as thick clients on host PCs. We use the term TransientPC systems to refer to these types of systems. The solution we propose, called TransPart , uses the higher-performing local storage of host hardware to speed up performance-critical operations. Our solution constructs a virtual storage device on demand (which we call transient storage ) by borrowing free disk blocks from the host’s storage. In this article, we present the design, implementation, and evaluation of a TransPart prototype, which requires no modifications to the software or hardware of a host computer. Experimental results confirm that TransPart offers low overhead and startup cost, while improving user experience.

YouChoose

Currently the QoS requirements for storage systems are usually presented in the form of service-level agreement (SLA) to bound I/O measures such as latency and throughput of I/O requests. However, SLA is not an effective performance interface for users to specify their required I/O service quality for two major reasons. First, for users it is difficult to determine appropriate latency and throughput bounds to ensure their required application performance without resource over-provisioning. Second, for storage system administrators it is a challenge to estimate a user’s real resource demand because the specified SLA measures are not consistently correlated with the user’s resource demand. This makes resource provisioning and scheduling less informative and can greatly reduce system efficiency. We propose the concept of reference storage system (RSS), which can be a storage system chosen by users and whose performance can be measured offline and mimicked online, as a performance interface between applications and storage servers. By designating an RSS to represent I/O performance requirement, a user can expect the performance received from a shared storage server servicing his I/O workload is not worse than the performance received from the RSS servicing the same workload. The storage system is responsible for implementing the RSS interface. The key enabling techniques are a machine learning model that derives request-specific performance requirements and an RSS-centric scheduling that efficiently allocates resource among requests from different users. The proposed scheme, named as YouChoose , supports the user-chosen performance interface through efficiently implementing and migrating virtual storage devices in a host storage system. Our evaluation based on trace-driven simulations shows that YouChoose can precisely implement the RSS performance interface, achieve a strong performance assurance and isolation, and improve the efficiency of a consolidated storage system consisting of different types of storage devices.

IATA 기반의 RAID5 분산 스토리지 서버의 설계 및 구현

iATA는 TCP/IP 네트워크상에서 ATA 명령어를 전달하기 위해 개발된 블록-레벨 프로토콜로서, 모바일 기기의 스토리지 한계를 극복하기 위한 대안으로 활용 될 수 있다. 본 논문은 RAID5 분산 스토리지 서버 개념을 iATA에 적용하여 스토리지 서버의 신뢰성과 속도를 개선하고자 한다. 분산 스토리지 서버중 하나의 서버가 다운된 경우에 나머지 서버 데이터의 XOR 함수를 적용하여 데이터 회복이 가능하며 이를 통해 데이터의 신뢰성을 높일 수 있다. 벤치마킹 실험과 시험을 통해 제안된 iATA 프로토콜은 제한된 스토리지를 가지고 있는 모바일 기기상에서 효율적이 고도 신뢰성 있는 가상 스토리지 프로토콜로서 사용될 수 있음을 보여주고 있다. iATA (Internet Advanced Technology Attachment) is a block-level protocol developed to transfer ATA commands over TCP/IP network, as an alternative network storage solution to address insufficient storage problem in mobile devices. This paper employs RAID5 distributed storage servers concept into iATA, in which the idea behind is to combine several machines with relatively inexpensive disk drives into a server array that works as a single virtual storage device, thus increasing the reliability and speed of operations. In the case of one machine failed, the server array will not destroy immediately but able to function in a degradation mode. Meanwhile, information can be easily recovered by using boolean exclusive OR (XOR) logical function with the bit information on the remaining machines. We perform I/O measurement and benchmark tool result indicates that additional fault tolerance feature does not delay read/write operations with reasonable file size ranged in 4KB-2MB, yet higher data integrity objective is achieved.

Virtual Control Storage-curity measures in VM/370

An experimental extension to VM/370 provides the virtual machine with a protected, fast-access execution and data domain. New capability in the form of a new instruction, whose meaning is defined by an arbitrary, protected program, is made available to the virtual machine. Protection is provided by basic, existing mechanisms in VM/370, namely virtual storage and virtual device management. Supervisor overhead required to support communication between a user and a server executing in vcs is minimized because the domain switch does not involve a virtual machine (task) switch, and because the interface provided is synchronous. The architecture of vcs is based on the concept of microcode which implements instructions for a machine architecture. When this concept is applied as a means of providing service to multiple users in a virtual machine environment, there are many interesting implications for the structure of the code that implements the service. The intention is to provide a system structure in which service can be provided in a way that avoids unnecessary invocation of function or duplication of function in server code and in the underlying control program.