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BLog

Log-block-based FTL (Flash Translation Layer) schemes have been widely used to manage NAND flash memory storage systems in industry. In log-block-based FTLs, a few physical blocks called log blocks are used to hold all page updates from a large amount of data blocks. Frequent page updates in log blocks introduce big overhead so log blocks become the system bottleneck. To address this problem, this paper presents a block-level log-block management scheme called BLog (Block-level Log-Block Management). In BLog , with the block level management, the update pages of a data block can be collected together and put into the same log block as much as possible; therefore, we can effectively reduce the associativities of log blocks so as to reduce the garbage collection overhead. We also propose a novel partial merge operation called reduced-order merge by which we can effectively postpone the garbage collection of log blocks so as to maximally utilize valid pages and reduce unnecessary erase operations in log blocks. Based on BLog , we design an FTL called BLogFTL for MLC NAND flash. We conduct experiments on a mixture of real-world and synthetic traces. The experimental results show that our scheme outperforms the previous log-block-based FTLs for MLC NAND flash.

마모도 평준화를 위한 File Clustering 알고리즘

Storage device based on Flash Memory have many attractive features such as high performance, low power consumption, shock resistance, and low weight, so they replace HDDs to a certain extent. An Storage device based on Flash Memory has FTL(Flash Translation Layer) which emulate block storage devices like HDDs. A garbage collection, one of major functions of FTL, effects highly on the performance and the lifetime of devices. However, there is no de facto standard for new garbage collection algorithms. To solve this problem, we propose File Clustering Algorithm. File Clustering Algorithm respect to update page from same file at the same time. So, these are clustered to same block. For this mechanism, We propose Page Allocation Policy in FTL and use MIN-MAX GAP to guarantee wear leveling. To verify the algorithm in this paper, we use TPC Benchmark. So, The performance evaluation reveals that the proposed algorithm has comparable result with the existing algorithms(No wear leveling, Hot/Cold) and shows approximately 690% improvement in terms of the wear leveling.

IntelliGenWiki: An Intelligent Semantic Wiki for Life Sciences

IntelliGenWiki: An Intelligent Semantic Wiki for Life Sciences

Medical Heritage Library

Screen reading on laptops, tablets, and devices is becoming a more widely accepted form of consuming information. As this trend develops, large-scale book digitization and metadata projects are becoming an increasingly important part of the library and information world. The Internet Archive, launched in 1996, was, along with the Gutenberg Project, one of the pioneer projects aimed at making large numbers of scanned texts and other digitized media forms freely available to users. Libraries, both academic and public, have adopted the Internet Archive's Texts section as a method of providing free access to scanned book content and accompanying metadata in a variety of file formats. One new book digitization project making use of the Internet Archive is the Medical Heritage Library (MHL), a cooperative endeavor of ten institutions that is funded by grants from the Arthur P. Sloan Foundation and the National Endowment for the Humanities. Participants include the National Library of Medicine and the libraries of Columbia, Harvard, and Yale Universities. The project was conceived in 2009 and made its debut the following year. It currently contains more than 28,000 scanned items. The MHL, modeled on the highly successful Biodiversity Heritage Library, is a collection of scanned public domain books on medicine, pharmacy, nursing, and allied areas. Its curators maintain a regularly updated home page and a Facebook page featuring news about the project, images from recently released books, and links to articles concerned with the history of medicine. MHL book scans are contributed by the participating institutions and are made available for in-browser reading and file download in a dedicated section of the Internet Archive. Basic metadata for each text is included, and downloads are available in portable document format (PDF), Kindle, and a variety of other file formats. A link is provided in the record for each book to a corresponding record in the Open Library, a supplementary project to the Internet Archive's Texts section, which attempts to offer a single open and publicly editable web page for every book in existence. Readers using the browser version can search inside the text and jump to the page on which the desired word is found. Three different page display options are available: one-page, two-page, and thumbnail views. The browser reader also features a read-aloud option, which uses optical character recognition (OCR) to treat the scanned images as an audio book. In addition to searching for items, users may browse the MHL by book title or by author. Users may also browse through a list of subjects and keywords assigned to items in the collection, although the terms used in this option are not clearly identified as being drawn from Library of Congress (LC), Medical Subject Headings (MeSH), or both controlled vocabularies. The quality of the scanned images is uniformly high. Color plates and illustrations in the originals are reproduced in color. The potential for special collections librarians and others to integrate the scanned books in the MHL and similar projects into their collections and reference work is tremendous. In addition to substantially broadening the scope of materials available to the researchers at a single institution, these images may contribute to the preservation of the originals by serving as digital copies. Opportunities for textual analysis, both large and small scale, are substantial as well (the growing field of digital humanities serves as one example). These uses, and others, invite exploration by librarians.

The history of Physics Update

<xhtml:span xmlns:xhtml="http://www.w3.org/1999/xhtml" xml:lang="en"> When <em>Physics Today</em> surveys its print readers and logs the habits of its online readers, the Physics Update department routinely comes top or near the top in popularity. Many online readers evidently like the department so much they bypass the homepage and go directly to the <a href="http://blogs.physicstoday.org/update/">Physics Update page</a>.</xhtml:span>

A framework to enable a gold sStandard of care for all people nearing the end of their life

The Gold Standards Framework (GSF) is a systematic, evidence-based approach to improve and optimise the organisation and quality of care for patients and their families or carers in the last year or years of life. It is concerned with helping people to ‘live well until the end of life’ and includes care in the final months or years of life for people with any end-stage illness in differing care settings. The work of the National GSF Centre, now based at Walsall teaching Primary Care Trust (tPCT), West Midlands, and linked with the University of Birmingham, includes three workstreams or programmes: primary care, care homes and other areas of support in end-of-life care. Welcome to the update page from the National GSF Centre. We are grateful to the editors of End of Life Care for inviting us to contribute a regular page to this excellent journal. …

A three-year study on the freshness of web search engine databases

This paper deals with one aspect of the index quality of search engines: index freshness. The purpose is to analyse the update strategies of the major web search engines Google, Yahoo, and MSN/Live.com. We conducted a test of the updates of 40 daily updated pages and 30 irregularly updated pages. We used data from a time span of six weeks in the years 2005, 2006 and 2007. We found that the best search engine in terms of up-to-dateness changes over the years and that none of the engines has an ideal solution for index freshness. Indexing patterns are often irregular, and there seems to be no clear policy regarding when to revisit Web pages. A major problem identified in our research is the delay in making crawled pages available for searching, which differs from one engine to another.

Extramural Research Updates Move Online

For the past 10 years, the NIEHS Division of Extramural Research and Training (DERT) has used the Extramural Update page in Environmental Health Perspectives (EHP) as a vehicle to communicate with the scientific community about new program initiatives, updates on NIH policy, programmatic accomplishments, leadership changes, and future directions at NIEHS. Highlights from past columns include: Research programs Programs featured in the Extramural Update have included Superfund, Environmental Health Sciences Core Centers, Children’s Centers, Parkinson’s Disease Collaborative Centers, and the Worker Education and Training Program. Newly developed programs described have included the DISCOVER Program, Outstanding New Environmental Scientists (ONES), and Oceans and Human Health. Community outreach and education programs Descriptions of the various education and outreach programs involved in translating research findings for different target audiences—including community organizations, health care professionals, and health decision makers—have highlighted the positives outcomes of these efforts. World Trade Center and Hurricane Katrina responses NIEHS and grantees have worked together to respond to environmental and public health needs resulting from these catastrophic events. New initiative planning from DERT retreats The extramural community was provided with a window into the research planning and priority-setting processes within DERT and NIEHS. The Division announced areas of research that were of interest to NIEHS in order to help guide potential applicants. Grantee and trainee recognitions Significant awards and honors attained by NIEHS grantees and trainees were communicated, such as the Karen Wetterhahn awards and NIEHS MERIT recipients. During the summer of 2007, NIEHS will launch a totally redesigned and updated website that will include a modern look, easier navigation, and new features to enhance its usability. DERT will use the new website to continue its communication with the extramural community. The change of venue will provide DERT with greater flexibility to respond more quickly to emerging events and issues of importance to the extramural community. The additional flexibility will also enable DERT to expand the content of the Extramural Update web page. As this change takes effect, look to the NIEHS website for the latest information and developments in extramural research that you have been used to seeing in the Extramural Update section of EHP. DERT wishes to thank the staff at EHP for the decade-long collaboration that has enhanced the visibility of DERT, its staff members, and its scientific programs and accomplishments. The Division looks forward to continuing its collegial and collaborative relationship with the journal in other areas of mutual benefit.

B-tree concurrency control and recovery in page-server database systems

We develop new algorithms for the management of transactions in a page-shipping client-server database system in which the physical database is organized as a sparse B-tree index. Our starvation-free fine-grained locking protocol combines adaptive callbacks with key-range locking and guarantees repeatable-read-level isolation (i.e., serializability) for transactions containing any number of record insertions, record deletions, and key-range scans. Partial and total rollbacks of client transactions are performed by the client. Each structure modification such as a page split or merge is defined as an atomic action that affects only two levels of the B-tree and is logged using a single redo-only log record, so that the modification never needs to be undone during transaction rollback or restart recovery. The steal-and-no-force buffering policy is applied by the server when flushing updated pages onto disk and by the clients when shipping updated data pages to the server, while pages involved in a structure modification are forced to the server when the modification is finished. The server performs the restart recovery from client and system failures using an ARIES/CSA-based recovery protocol. Our algorithms avoid accessing stale data but allow a data page to be updated by one client transaction and read by many other client transactions simultaneously, and updates may migrate from a data page to another in structure modifications caused by other transactions while the updating transaction is still active.

Conference Calendar - update page number only from 13/7

Conference Calendar - update page number only from 13/7

The evolution of a manufacturing Web site

The Boeing Commercial Airplanes Wing Responsibility Center (WRC) needed a way to communicate quickly and effectively between its various plant locations. An important requirement was the ability to provide a common means to update and disseminate information, such as vital organizational statistics, in a timely manner.Several Web applications were built for the site, providing data entry and validation, charting, reporting, paging, e-mail notification, automatic detection of broken links, and the ability to build and update pages without the knowledge of HTML or a Web authoring tool. The site and its applications work daily to support the people who build the wings for Boeing airplanes.

On coupling multiple systems with a global buffer

We conduct a performance study of coupling multiple systems with a global buffer, and present several results obtained from a multiple-system simulator. This simulator has been run against three workloads, and the coupled system behavior with these three different inputs is studied. Several statistics, including those on local and global buffer hits, page writes to the global buffer, cross-invalidations, and castouts are reported. Their relationship to the degree of data skew is explored. Moreover, in addition to the update-caching approach, a design alternative for the use of a global buffer, namely read-caching, is explored. In read-caching, not only updated pages but also pages read by each node are kept in the global buffer, thereby facilitating other nodes access to the same pages at the cost of a higher global buffer usage. Also investigated is the case of no-caching, i.e., without using a global buffer. Several simulation results are presented and analyzed.

Performance analysis of buffer coherency policies in a multisystem data sharing environment

Six buffer coherency policies for a multisystem transaction processing environment are compared. These policies differ in their basic approaches on how and when the invalidated pages are identified or if the updated pages are propagated to the buffers of the remote nodes. They can be classified as detection, notification (of invalid pages), and (update) propagation oriented approaches. The policies trade off CPU overhead of coherency messages with buffer hit probability in different ways, resulting in a tradeoff of response time and maximum throughput. The main contribution is to develop analytical models to predict buffer hit probabilities under various buffer coherency policies assuming the LRU replacement policy and the independent reference model (IRM). The buffer models are validated using simulation models and show excellent agreement. Integrated analytic models capturing buffer hit probability and CPU overhead are developed to predict the overall response times under these coherency policies. The difference in buffer hit probabilities amongst various policies are found to be very sensitive to the skewness of the data access.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A study of checkpoint generations for a database recovery mechanism

This paper discusses checkpoint generations for a database recovery mechanism. The density of checkpoint generations is analytically derived from minimizing the expected total overhead to completion of a phase, and this density yields the optimum sequence of checkpoint generations measured in unit of update pages. We further present the numerical examples for the results obtained and show that the sequence gives effective checkpoint generations.