Stable-Storage Implementation Maintain multiple copies of each block on separate disks copies can be at remote sites to protect against disasters such as fire or flooding. Failure during data transfer can still result in inconsistent copies:Block transfer can result in Successful completion Partial failure:destination block has incorrect information Total failure:destination block was never updated Protecting storage media from failure during data transfer(one solution): 。 Execute output operation as follows (assuming two copies of each block): 1.Write the information onto the first physical block. 2.When the first write successfully completes,write the same information onto the second physical block. 3.The output is completed only after the second write successfully completes. Database System Concepts-7th Edition 19.6 @Silberschatz,Korth and SudarshanDatabase System Concepts - 7 19.6 ©Silberschatz, Korth and Sudarshan th Edition Stable-Storage Implementation ▪ Maintain multiple copies of each block on separate disks • copies can be at remote sites to protect against disasters such as fire or flooding. ▪ Failure during data transfer can still result in inconsistent copies: Block transfer can result in • Successful completion • Partial failure: destination block has incorrect information • Total failure: destination block was never updated ▪ Protecting storage media from failure during data transfer (one solution): • Execute output operation as follows (assuming two copies of each block): 1. Write the information onto the first physical block. 2. When the first write successfully completes, write the same information onto the second physical block. 3. The output is completed only after the second write successfully completes