CPSC-608 Database Systems Fall 2011 Instructor: Jianer Chen Office: HRBB 315C Phone: Notes #13

Coping with System Failures System may fail because of Program or data errors Disk crashes Computer room fires System fails (power off, code execution errors)

Coping with System Failures System may fail because of Program or data errors Disk crashes Computer room fires System fails (power off, code execution errors) System programs cannot help }

Coping with System Failures System may fail because of Program or data errors Disk crashes Computer room fires System fails (power off, code execution errors) A recovery program may help

Coping with System Failures Facts Main memory is volatile; Disk is non-volatile.

Coping with System Failures What we want to recover: Partial changes by a transaction

Coping with System Failures What we want to recover: Partial changes by a transaction What is a transaction? Some thing you want it be a single logic step

Coping with System Failures What we want to recover: Partial changes by a transaction What is a transaction? Some thing you want it be a single logic step What is a logic step? ACID: Atomicity, Consistency, Isolation, and Durability

secondary storage (disks) database administrator DDL language database programmer DML (query) language DBMS file manager buffer manager main memory buffers index/file manager DML complier DDL complier query execution engine transaction manager concurrency control lock table logging & recovery Graduate Database

secondary storage (disks) database administrator DDL language database programmer DML (query) language DBMS file manager buffer manager main memory buffers index/file manager DML complier DDL complier query execution engine transaction manager concurrency control lock table logging & recovery Graduate Database