MODELING AND EVALUATION OF A HYBRID OPTICAL AND MAGNETIC DISK STORAGE ARCHITECTURE

A hybrid storage system combining optical disks and magnetic disks is proposed and evaluated via mathematical models. Unlike most current applications of optical disk technology, which consider static databases or deferred update, this research considers environments with a moderate level of near real-time updates. An example of such an environment is databases for administrative decision support systems (DSS). The proposed hybrid storage system uses a write-once, read-many optical disk device (ODD) for the database and a conventional magnetic disk (MD) for storage of a differential file. Periodically, the differential file is used to refresh the ODD file by writing updated records to free space on the ODD. When available free space on the ODD is exhausted, the file is written to new ODD media - - a reorganization operation. Models of storage cost are developed to determine the optimum refresh cycle time, t*, and optimum reorganization cycle time, T*. Parameters of the model include data file volatility, file size, device costs, and costs for refresh and reorganization. Numerical results indicate that the hybrid system is attractive for a broad range of database environments

A differential refresh scheme for remote end-user\u27s views

The growth of end-user computing and recent developments in information technology, such as client/server architecture and data warehouse, promote the use of remote materialized views (RMVs) to support end-users. This article presents a differential scheme to refresh remote end-user\u27s views. The scheme stores the effects of updates relevant to the RMV in a difference table which is transmitted to the remote site upon receiving the refresh request to update the RMV. The scheme provides a fast response to a user\u27s refresh request. We discuss the data structures and algorithms of the scheme. Performance measures are developed and compared with the regeneration scheme

Mortality and cost outcomes of elderly trauma patients admitted to intensive care and the general wards of an Australian tertiary referral hospital

COPYRIGHT 2009 Australian Society of AnaesthetistsMortality and cost outcomes of elderly intensive care unit (ICU) trauma patients were characterised in a retrospective cohort study from an Australian tertiary ICU Trauma patients admitted between January 2000 and December 2005 were grouped into three major age categories: aged > or =65 years admitted into ICU (n = 272); aged -65 years admitted into general ward (n = 610) and aged or = 65 years, ventilated) were: ICU or = 65 not-ventilated (OR 0.061) and ward > or = 65 (OR 0.086); increasing injury severity score and increased Charlson comorbidity index of 1 and 2, compared with zero (OR 2.21 [1.40 to 3.48] and OR 2.57 [1.45 to 4.55]). The raw mean daily ICU and hospital costs in A$2005 (US$) for age or = 65 to ICU, and > or = 65 to the ward were; for year 2000: ICU, $2717 (1462) and$2777 (1494); hospital, $1837 (988) and$1590 (855); ward $933 (502); for year 2005: ICU,$3202 (2393) and $3086 (2307); hospital,$1938 (1449) and $1914 (1431); ward$1180 (882). Cost increments were predicted by age < or = 65 and ICU admission, increasing injury severity score, mechanical ventilation, Charlson comorbidity index increments and hospital survival. Mortality cost-effect was estimated at -63% by least squares regression and -82% by treatment-effects regression model. Patient demographic factors, injury severity and its consequences predict both cost and survival in trauma. The cost mortality effect was biased upwards by conventional least squares regression estimation.L.Y.L. Chan, J.L. Moran, C. Clarke, J. Martin and P.J. Solomo