Abstract: Due to the heterogeneity and dynamicity of grid resources,therc arc a lot of problems unsolved in grid task scheduling. To cope with the shortcoming of traditional reliability evaluation model, a new type of failure named dead- line-missing-failure was introduced to support reliability evaluation for tasks with deadline constraint. Considering the impact of local tasks, we used a stochastic service model to describe dynamic workloads of Grid resources. A corre- sponding calculation method and proof for resource reliability were proposed. Based on the proposed grid resource relia- bility evaluation modcl,a mufti objective grid task scheduling model was presented. hhe task scheduling was formulated as an optimization problem to maximize the reliability and minimize the cost. Fer the issue, a chemical reaction optimiza- tion algorithm, called CRO, was developed to solve the NP problem. Experimental results verify the performance of pro- posed reliability model and CRO algorithm is superior to GA and PSO for Grid reliability-cost optimization problem in quality and cffcicncy.

Key words: Chemical reactive optimization, Grid, Reliability, Cost, Scheduling algorithm, Stochastic service model