Database Management System · Unit 9
Database Recovery and Reliability
Exam-focused notes for Database Recovery and Reliability (Database Management System, BIT202): what the TU syllabus asks and how it has actually been tested, with 5 solved past questions from this unit.
What this unit covers
- Database recovery definition
- System log and log entries
- Types of failures
- Catastrophic failure
- Shadow paging technique
- Recovery using shadow paging
Database recovery definition
What is database recovery? How can shadow paging be used for database recovery? [5]
Database recovery is the process of restoring a database to a correct and consistent state after a failure (such as system crash, transaction failure, media failure, or power loss). The primary goals of database recovery are: - Atomicity: Ensure that incomp...
Full solved answer →Shadow paging technique
What is shadow paging? How it is used for database recovery? [5]
Shadow paging is a recovery technique used in database systems that maintains two page tables simultaneously: - Current Page Table - reflects all changes made by the current (active) transaction. - Shadow Page Table - a copy of the page table taken at the s...
Full solved answer →What is shadow paging? How it is used for database recovery? [5]
Shadow paging is a recovery technique used in database management systems that maintains two page tables simultaneously: - Current Page Table - reflects all changes made by the current (active) transaction. - Shadow Page Table - a copy of the page table tak...
Full solved answer →System log and log entries
What is the system log used for? What are the typical kinds of entries in a system log? [5]
Note: The reference notes did not contain specific content on this topic. The following answer is based on standard Operating Systems concepts as taught in BSc CSIT curriculum. --- A system log (also called a log file or audit log) is a file maintained by t...
Full solved answer →Types of failures
Discuss the different types of failures. What is meant by catastrophic failure? [5]
In software engineering and system reliability, failures are broadly classified into the following types: --- - Failures that occur only under certain input conditions. - They appear temporarily and may not be reproducible every time. - Example: A program c...
Full solved answer →Make Unit 9 stick
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