CORE: Augmenting Regenerating-Coding-Based Recovery for Single and Concurrent Failures in Distributed Storage Systems

Data availability is critical in distributed storage systems, especially when node failures are prevalent in real life. A key requirement is to minimize the amount of data transferred among nodes when recovering the lost or unavailable data of failed nodes. This paper explores recovery solutions based on regenerating codes, which are shown to provide fault-tolerant storage and minimum recovery bandwidth. Existing optimal regenerating codes are designed for single node failures. We build a system called CORE, which augments existing optimal regenerating codes to support a general number of failures including single and concurrent failures. We theoretically show that CORE achieves the minimum possible recovery bandwidth for most cases. We implement CORE and evaluate our prototype atop a Hadoop HDFS cluster testbed with up to 20 storage nodes. We demonstrate that our CORE prototype conforms to our theoretical findings and achieves recovery bandwidth saving when compared to the conventional recovery approach based on erasure codes.Comment: 25 page

Assessing the Risk of 100-year Freshwater Floods in the Lamprey River Watershed of New Hampshire Resulting from Changes in Climate and Land Use

What is the coastal resource issue the project sought to address? Both the magnitude and frequency of freshwater flooding is on the rise in seacoast NH and around much of New England. In the Great Bay watershed, this is the result of two primary causes: 1) increases in impervious surface stemming from a three-to-four fold increase in developed land since 1962; and 2) changing rainfall patterns in part exemplified by a doubling in the frequency of extreme weather events that drop more than 4 inches of precipitation in less than 48 hours (Wake et al., 2011) over the same time period. Moreover, the size of the 100-year precipitation event in this region has increased 26% from 6.3 inches to 8.5 inches from the mid 1950’s to 2010 (NRCC and NRCS, 2012). One consequence is the occurrence of three 100-year floods measured on the Lamprey River at Packers Falls since 1987, and a fourth if the three days of flooding in March of 2010 had occurred instead in two days (Figure 1). Flooding events are expected to continue to increase in magnitude and frequency as land in the watershed is further developed and climate continues to change in response to anthropogenic forcing (e.g., Hayhoe et el., 2007; IPCC, 2007; Karl et al., 2009). Land use management strategies, in particular low impact development (LID) zoning requirements, are one strategy that communities can employ for increased resiliency to flooding with the greatest influence in urban environments

Platte River Basin Study

Under the Western Water Policy Review Act of 1992 (P.L. 102-575, Title XXX), Congress directed the President to undertake a comprehensive review of Federal activities in the 19 Western States that directly or indirectly affect the allocation and use of water resources, whether surface or subsurface, and to submit a report of findings to the congressional committees having jurisdiction over Federal Water Programs

Assessing the Risk of 100-year Freshwater Floods in the Lamprey River Watershed of New Hampshire Resulting from Changes in Climate and Land Use

What is the coastal resource issue the project sought to address? Both the magnitude and frequency of freshwater flooding is on the rise in seacoast NH and around much of New England. In the Great Bay watershed, this is the result of two primary causes: 1) increases in impervious surface stemming from a three-to-four fold increase in developed land since 1962; and 2) changing rainfall patterns in part exemplified by a doubling in the frequency of extreme weather events that drop more than 4 inches of precipitation in less than 48 hours (Wake et al., 2011) over the same time period. Moreover, the size of the 100-year precipitation event in this region has increased 26% from 6.3 inches to 8.5 inches from the mid 1950’s to 2010 (NRCC and NRCS, 2012). One consequence is the occurrence of three 100-year floods measured on the Lamprey River at Packers Falls since 1987, and a fourth if the three days of flooding in March of 2010 had occurred instead in two days (Figure 1). Flooding events are expected to continue to increase in magnitude and frequency as land in the watershed is further developed and climate continues to change in response to anthropogenic forcing (e.g., Hayhoe et el., 2007; IPCC, 2007; Karl et al., 2009). Land use management strategies, in particular low impact development (LID) zoning requirements, are one strategy that communities can employ for increased resiliency to flooding with the greatest influence in urban environments

Settling Basins and Terraces for Cattle Manure (2002)

Fast-moving liquids pick up and transport solids, which settle out of the flow when velocity is reduced. Often, settling basins are designed to limit flow velocities to 1.5 feet per second, or less. Settling may remove 35 percent to 60 percent of the solids from a dilute liquid slurry, with as little as 10 minutes detention time (30 to 60 minutes detention time is common).New 3/02/3.5

Settling basins and terraces for dairy waste (1995)

"New/8/95/3.5M.""Water Quality.""Focus area : nutrients and bacterial wastes.""Published by University Extension, University of Missouri-System.

Decade of SCADA implementation, A

Presented at Meeting irrigation demands in a water-challenged environment: SCADA and technology: tools to improve production: a USCID water management conference held on September 28 - October 1, 2010 in Fort Collins, Colorado.Irrigated agriculture began in southwest Idaho's Lower Payette Valley in the 1880's. By 1900, over 30,000 irrigated acres had been developed, served by a system of over 20 canals diverting natural flows. High springtime river flows were often reduced to a trickle by August. Two Bureau of Reclamation dams were built to provide supplemental storage and to bring another 53,000 acres into production. Like many early canal systems, the Payette Valley canals were built with only a few manually operated water control structures or water measurement devices. Diversions were difficult to control due to variable river flows and much water was wasted. Water rights were difficult to administer, due to the lack of accurate water measurement. In dry years there were often disputes among users on different canals as natural flows declined. In 1997, the first canal headworks in the Payette were automated, utilizing solar power and simple off-the-shelf components. The success of this single project encouraged more irrigation entities to improve water control capabilities utilizing SCADA. New control structures were built and automated and communication links were put in place to monitor canal operations and to update water accounting. Today, there are over 40 automated control gates, 14 telemetered water measurement sites, and 11 new water measurement structures. Diversion data daily and accurately account for water use in the basin. Telemetry has enabled canal operators to monitor facilities and to respond quickly to changing water needs or emergency situations. Canal systems in the valley are being operated more efficiently, reducing both diversion rates and operational spills. This more efficient operation has helped to improve water supply reliability. These changes have also served to bring a greater sense of cooperation to water users throughout the Payette Valley

A study of the break-up characteristics of Chena River Basin using ERTS imagery

The author has identified the following significant results. The Chena River Basin was selected because of the availability of ground truth data for comparison. Very good agreement for snow distribution and rates of ablation was found between the ERTS-1 imagery, the snowmelt model, and field measurements. Monitoring snowmelt rates for relatively small basins appears to be practical. The main limitation of the ERTS-1 imagery is the interval of coverage. More frequent overflights providing coverage are needed for the study of transient hydrologic events. ERTS-1 data is most useful when used in conjunction with snowmelt prediction models and existing snow course data. These results should prove very useful in preliminary assessment of hydrologic conditions in ungaged watersheds and will provide a tool for month-to-month volume forecasting