Introduction Parallel machines have become quite common and affordable prices of microprocessors,memory and disks have dropped sharply Data storage needs are growing increasingly large user data at web-scale 100's of millions of users,petabytes of data transaction data are collected and stored for analysis. multimedia objects like images/videos Parallel storage system requirements storing large volumes of data processing time-consuming decision-support queries providing high throughput for transaction processing Very high demands on scalability and availability Database System Concepts-7th Edition 21.2 ©Silberscha乜，Korth and SudarshanDatabase System Concepts - 7 21.2 ©Silberschatz, Korth and Sudarshan th Edition Introduction ▪ Parallel machines have become quite common and affordable • prices of microprocessors, memory and disks have dropped sharply ▪ Data storage needs are growing increasingly large • user data at web-scale ▪ 100’s of millions of users, petabytes of data • transaction data are collected and stored for analysis. • multimedia objects like images/videos ▪ Parallel storage system requirements • storing large volumes of data • processing time-consuming decision-support queries • providing high throughput for transaction processing • Very high demands on scalability and availability