Energy-efficient disk replacement and file placement techniques for mobile systems with hard disks

Chapter 6 - Secondary Storage

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.

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.

The problem of distributing a Cartesian product file on multiple disks to maximize the parallelism for partial match queries is addressed. C. Faloutsos et al. (1989) have proposed an allocation method for Cartesian product files on multiple disks by using linear error-correcting codes. The performance of the allocation method is analyzed. Some conditions under which the allocation method is strictly optimal for queries with a given number of unspecified attributes are presented. A necessary and sufficient condition for a linear code to give a strictly optimal allocation method is discussed. Formulas for the average response time on queries with w unspecified attributes, denoted T/sub w/, in terms of the weight distribution of the code or its dual code, and formulas for the average response time Ton all queries, are given. Several examples whose average response times T/sub w/ or T are close to theoretical lower bounds are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Motivation: Regulatory, non-coding RNAs often function by forming a duplex with other RNAs. It is therefore of interest to predict putative RNA–RNA duplexes in silico on a genome-wide scale. Current computational methods for predicting these interactions range from fast complementary-based searches to those that take intramolecular binding into account. Together these methods constitute a trade-off between speed and accuracy, while leaving room for improvement within the context of genome-wide screens. A fast pre-filtering of putative duplexes would therefore be desirable.Results: We present RIsearch, an implementation of a simplified Turner energy model for fast computation of hybridization, which significantly reduces runtime while maintaining accuracy. Its time complexity for sequences of lengths m and n is with a much smaller pre-factor than other tools. We show that this energy model is an accurate approximation of the full energy model for near-complementary RNA–RNA duplexes. RIsearch uses a Smith–Waterman-like algorithm using a dinucleotide scoring matrix which approximates the Turner nearest-neighbor energies. We show in benchmarks that we achieve a speed improvement of at least 2.4× compared with RNAplex, the currently fastest method for searching near-complementary regions. RIsearch shows a prediction accuracy similar to RNAplex on two datasets of known bacterial short RNA (sRNA)–messenger RNA (mRNA) and eukaryotic microRNA (miRNA)–mRNA interactions. Using RIsearch as a pre-filter in genome-wide screens reduces the number of binding site candidates reported by miRNA target prediction programs, such as TargetScanS and miRanda, by up to 70%. Likewise, substantial filtering was performed on bacterial RNA–RNA interaction data.Availability: The source code for RIsearch is available at: http://rth.dk/resources/risearch.Contact:gorodkin@rth.dkSupplementary information:Supplementary data are available at Bioinformatics online.

High performance and energy-efficient storage systems are essential for mobile data-intensive applications such as remote surgery and mobile data center. Existing mobile storage systems consist of an array of independent small form factor hard disks connected to a host by a storage interface in a mobile computing environment. Although hard disks are cost-effective and can provide huge capacity and high-throughput, they have some intrinsic limitations such as long access latencies, high annual disk replacement rates, fragile physical characteristics, and energy-inefficiency. Compared with hard disk drives, solid state disks (SSD) are much more energy-efficient, and can offer much faster access times. A major concern on current solid state disk is its relatively higher price. In this paper, we developed hybrid mobile disk architecture HyBuM that integrates an array of solid state disks with buffer disks and an array of mobile disks. The most recently used data will be cached in the solid state disks, the second most popular data will be stored in the buffer disks, and the least used data sets will be stored in the mobile disk array. Experimental results demonstratively show that HyBuM provides significant energy saving for mobile storage systems such as laptops, mobile phones, and PDA compared to two existing non hybrid architecture.

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.

Storage and retrieval of database constraints

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.

A recent study puts the number of mobile phones in use around the world at an astonishing 5 billion and these numbers are growing rapidly. This places the increase in energy consumption of mobile phones in the world at an alarming level. Wi-Pie or Wireless-Piezoelectric technique combines RF energy scavenging and piezoelectric energy harvesting technologies to provide an alternative method of powering mobile electronic devices. By placing piezoelectric crystals beneath the keypad of a mobile phone, we intend to generate a small voltage with every key press which could be stored in a secondary storage device like a capacitor. The charge accumulated in the device can then be transferred to the primary storage or the battery so that the use of external chargers can be minimized. Additional power management circuitry is used to intercept the known and the unknown sources of ambient RF radiations. The received RF power is converted to DC and conditioned before it's delivered to the load. Although the RF energy levels are low, a combination of the harvesting and scavenging techniques will provide a significant source of power.

The authors presents performance analysis of a concurrent file reorganization algorithm. They examined the effect of buffer size, degree of reorganization, and write probability of transactions on system throughput. The problem of file reorganization considered involves altering the placement of records on pages on a secondary storage device. This reorganization must be done in-place. The approach is appropriate for a non-in-place reorganization. The motivation for such a physical change is to improve the database system's performance, by minimizing the number of page accesses made in answering a set of queries. It is shown through simulation that the algorithm, when run concurrently with user transactions, provides an acceptable level of overall database system performance. >