Disk Drive I/O Commands and Write Blocking

Chapter 6 - Secondary Storage

Storage and retrieval of database constraints

An archiving model for a hierarchical information storage environment

Exploring new electrolyte materials is important to comprehend high performance secondary charge storage devices for effective utilization of renewable energy. Ionic liquids with broad electrochemical voltage window and wide range of thermal stability are prospective materials for the same. As an improved version of this class of materials, we report herein, on the synthesis of novel pyrrolidinium based ionic liquid tethered nanoparticle hybrid electrolytes and compared their conductivity and electrochemical cycling behaviors. Hybrid electrolytes are prepared by covalently grafting N-Methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl) imide to the surfaces of pre-synthesized TiO2 nanoparticles at three different core volume fractions, ranging from 0.11 to 0.46. Uniform dispersion of the core nanoparticle within the matrix of the electrolytes improves their mechanical properties. With increasing core volume fractions, the electrical conductivity slightly decreases due to increasing viscosity. Nevertheless, nanoparticle grafting significantly improves the electrochemical performance of the electrolytes. The electrolytes show very good capacitance retentivity (>90%) and long-term cycling stability above room temperature even at the lowest grafting density within symmetric stainless steel electrodes. Impressive room temperature electrochemical performance of these materials within symmetric supercapacitor cell containing CMS graphite as electrodes further demonstrates the applicability of these hybrid materials as promising electrolytes for secondary charge storage devices.

One of the key components of a hybrid electric vehicle (HEV) drive train is its secondary energy storage device. The automotive industry is still in the process of debating on the fact, as to which device provides the best option in HEVs, for the purpose of load leveling. This paper aims at providing a fair idea with regards to the selection of secondary energy sources, based on vehicle performance characteristics and overall drive train efficiency. The performances of lead-acid (PBA), lithium-ion (Li-Ion), nickel-cadmium (Ni-Cd), nickel-metal hydride (Ni-MH), and nickel-zinc (Ni-Zn) batteries, as well as ultra-capacitors (UC) are investigated over city and highway driving schedules for a heavy-duty diesel-parallel hybrid transit bus application. Based on the simulation studies for the above-mentioned storage devices, the Ni-MH, PBA, and the ultra-capacitor technologies demonstrate best results in terms of fuel economy and percentage drive train efficiency. On the other hand, the Ni-Zn and Li-Ion batteries show much promise, but still demand a great deal of research and development work, before they become a viable option for HEV applications. Finally, the paper compares and summarizes critical performance characteristics for the energy storage devices under investigation.

A very fast parallel object store for very fast applications

Performance analysis of an Injera baking machine by using solar energy

In Memory Computing is moving data into dynamic memory which is traditionally stored in secondary storage devices. In this paper we try to improve the capability of Java Virtual Machine (JVM) to process large data collections/application by pertinence of In-Memory Computing concepts. It helps JVM/processor to process huge data sets efficiently due to high-speed access and reduction of latency of slow secondary storage devices. It is implemented by providing more dynamic memory to JVM or by the implementation of In Memory Database concepts. In this paper we correlate Actual machine with JVM and try to improve ability of JVM to process large data collections by eliminating disk access and replacing Database with JAVA Collections in the Model Layer hence using `in memory' concepts, Henceforth a high performance system is designed.

The problem of determining page size in a page on demand system is discussed in detail in this paper. After having introduced the problem, the effect page size may have on various system performance measures is reviewed based on measurements of program behaviour and on simple models of system behaviour. This discussion is followed by a detailed study of the effect of the choice of page size on the efficient utilization of primary memory space. The wasted space-time integral (WSTI) of primary memory space is selected as a measure of this utilisation and a new model of program and system behaviour is used to compute the WSTI for different secondary memory devices (drum, ECS and LCS) and different system behaviour parameters such as the time spent in supervisor mode by the operating system to initiate a page transfer, the time spent in the CPU queue by a program which has recovered from a page fault before it receives the attention of the CPU, the global page fault rate (or arrival rate at the secondary storage devices used for paging) and other factors. The influence of each of these factors is discussed and analyzed, and the conditions under which one or another of these dominates the problem is identified. In the Appendix, one of the problems posed by our model, the use of approximate formulae for fragmentation which remain valid for a large class of probability distribution functions of program size, is analyzed in detail. Some tests are developed for the validity of these formulae.

Efficient buffering for concurrent disk and tape I/O

An evaluation is made of a way to reduce the cost of program restructuring by having a compiler determine the program's packing in virtual address space from an analysis of its source code. Two features of this method are the duplication of code modules in virtual address space and the inline substitution of the code for a called procedure. This compile-time restructuring algorithm is evaluated using the instruction-only address traces from a collection of programs. In a simulation of a virtual memory system using disks as secondary storage devices, the method is not successful, since it leads to a higher optimum space-time execution cost than that of the unrestructured program. The algorithm did reduce program space-time execution cost for some arbitrarily chosen memory allocations smaller than the optimum. This could be useful in a multiuser, multiprogrammed environment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Audit software for data analytics, most commonly known as Generalised Audit Software (GAS), has been used by audit organisations since the deployment of IT in business organisations. The use and importance of GAS has increased with the growth in the sophistication and proliferation of IT within business organisations. Despite this development, recent studies have reported that GAS is still underused and identified that the factor contributing most to such underutilisation of GAS is access to organisational data. Although the current state of GAS enables auditors to directly access data stored in databases, it is still uncommon for auditors to use this GAS capability. Auditors more commonly obtain organisational data from the auditees’ staff by using secondary storage devices. The audit literature has found problems associated with analysing auditee-provided data, for example, being presented with manipulated data and has, therefore, advocated the importance of having direct access to organisational data. The literature further claims that having direct access to organisational data would provide greater benefits to audit organisations from their investments in GAS through, for example, improved audit efficiency and effectiveness. The audit literature, however, provides limited empirical evidence to support such a recommendation. This thesis seeks empirical evidence on the impact of having direct access to organisational data on the quality of auditor’s analytical tests as representing the dimension of actual audit quality. Drawing on the theory of flow, a supportive condition for innovative behaviour, this study posits that having direct access to organisational data facilitates the creation of a flow state. When auditors experience flow state, they are motivated to use GAS more innovatively. Further, as auditors’ innovative use of GAS increases, auditors are better able to identify successful applications of GAS that, in turn, improve the quality of their analytical tests. This thesis uses a mixed-method approach involving both interviews and a survey to gather data to test its research hypotheses. The interviews and the survey targeted auditors with differing levels of seniority who have used GAS or are actively involved in using it for auditing. The results show support for the research model. The results indicate that, having a sense of control over the use of GAS, the ability to focus on interactions using GAS, the extent of auditors’ professional scepticism, and having knowledge/skills of GAS motivates auditors to use GAS innovatively. The results also indicate that, when the innovative use of GAS increases, the quality of analytical tests also increases. Analysis of the impact of having direct, compared to indirect, access to organisational data shows a statistically significant moderating effect on the extent of auditors’ professional scepticism and on their ability to focus on their interactions with GAS. The results indicate that auditors’ professional scepticism increases, while their ability to focus on the interaction decreases when they have direct access to organisational data. Analysis of the effect of direct access also found no statistically significant difference in the quality of auditor’s analytical tests. These findings enrich current discussion within IT auditing literature on the effectiveness of IT-based audit procedures to obtain audit evidence. This thesis demonstrates that innovative use of GAS is an appropriate link between IT-based audit methods and audit quality, a matter that has been barely elaborated. Additionally, this thesis identifies that the length of GAS experience affects both auditors’ preferences about type of data access (i.e., direct versus indirect access) and their perceptions of the benefits of data access on audit quality. Audit organisations might, therefore, conceive strategies to shorten the time required to realise the benefits of using GAS to directly access organisational data.

The present work reports the automatic vehicle identification (AVI) system using RFID signals. Sensor is incorporate in the electronic family; it is used in many fields. In this paper, we propose the photoelectric sensors as a vehicle detection tool in an RFID based poultry traceability system. In this system the vehicle is tapered with barcodes on the number plates, all the information about vehicle like vehicle register number, vehicle owner name, address of the owner and all the specifications about the vehicle are tapered as barcodes and the RFID based poultry traceability system is fixed at every check point, when the vehicle passes through this check point the RFID signals scan the bar codes and send the information to the main server. In the main server the information is stored in the secondary storage device (ssd) and it can be verified at any time easily. By using this system we can collect toll fares, insurances etc., efficiently without humans and we can also reduce the accidents on highways by controlling the vehicle speed, if any vehicle tolerates the rules like over speed, the check points the sensors warns the driver by displaying the message on the screens and also send the vehicle information to the traffic controllers and to main server simultaneously with in fraction of seconds using general packet radio service (gprs). There is no need to supply power to this system because the dc motor available in this system converts the pressure obtain from the vehicles to electric energy. Finally, the concept shown in this paper is highly reliable system for identification of vehicles in this electronic world.

An economical method for maintaining routing records in an automated record keeping system is described. Routing records are stored separately from data records on secondary storage devices. A time stamp is stored in each routing record, and all routing records associated with the same data record are linked by a time link. The method is shown to have better performance and lower impact on the remainder of the system than several alternative strategies.

Mobile systems have usually used hard disks as the secondary storage devices because of their high capacity per cost and high I/O throughput. However, their high power consumption is the main limiting factor for extending their adoptions in mobile systems. In this paper, we propose enhanced file placement techniques for mobile platforms with multiple smaller disks (instead of a single large disk). We investigate that how many smaller disks are necessary to obtain energy saving while maintaining the required performance using both a simplified energy model and a realistic trace-based simulator under the proposed multiple disk configurations. We also propose energy-efficient file placement techniques, which aggregate files with common attributes the same set of disks. By skewing I/O operations, the proposed techniques achieve additional energy saving. Experimental results show that the proposed techniques can reduce the energy consumption by up to 43% when eight 1 disks are used instead of a single 2.5 disk with an acceptable increase in the average response time.