Please enable JavaScript.
Coggle requires JavaScript to display documents.
Backups - Coggle Diagram
Backups
Recovery and Atomacity
Log Records
Use in recording database modifications
The log is a sequence of log records
Several types of log records in a update log record
Transaction identifier
Data-item identifier
Old value
New value
Database Modification
The Transaction performs computations in private part of memory
The Transaction modifies the data block
The database systen executes the output operation
Concurrency Control and Recovery
Prevent a transaction from modifying data of another transaction
Transaction Commit
A transaction has commited when has been output to stable storage
CheckPoins
Not permit any updates to be performed while the checkpoint operation is in progress
Buffer Management
Log- Record Buffering
Database buffering
Operating System Role in Buffer Management
Fuzzy Checkpointing
Early Lock Release and Logical Undo
Operations
Logical Operations
Logical Undo Log Records
Transaction Rollback with Logical Undo
Concurrency Issues in Logical Undo
ARIES**
Data Structures
Recovery Algorithm
Analysis Pass
Redo Pass
Undo Pass and Transaction Rollback
Other Features
Recovery Algorithm
Transaction Rollback
Register information to log for rollback
Recovery After a System Crash
The redo phase, all transactions recovery to the last checkpoint
Undo phase, the system rolls back all transactions
Failure Classification
Types
Transaction failure
Logical Error
Do not continue with your normal execition
System Error
The system has entered an undesired state
System crash
There is a hardware malfunction
Disk failure
A disk block loses its content
Storage
Categories
Volatile Storage
Nonvolatile Storage
Stable Storage
Replicate information in nonvolatile storage media
Protection from failure during data transfer
Successful completion
The information arrived safely
Partial failure
A failure occurred in the transfer and has incorrect information
Total failure
The failure occurred early dureng the transfer
Failure with Loss of Nonvolatile
Storage
Remote Backup Systems