1. Oracle Database High Availability
Brandon Kuschel
Jian Liu
Source:
Oracle Database 11g Release 2 High Availability
An Oracle White Paper
November 2010

2. Overview Human Error Protection Data Corruption Protection
Oracle Flashback Technologies
Oracle Recovery Manager
Data Corruption Protection
Fast Recovery Area
Oracle Secure Backup
Data Recovery Advisor
Storage Failure Protection
Automatic Storage Management
Site Protection
Oracle Data Guard
Oracle GoldenGate

3. Oracle Database's HA Solution Set

4. Human Error Protection
Example: Bug in SQL statement
Isolation: Preventing errors via access control
Faster recovery with Flashback technologies
Undo: Query
Undo: Versions Query:
SELECT * FROM emp VERSIONS BETWEEN TIMESTAMP time1 AND time2 WHERE…
Transaction Query:
SELECT * FROM FLASHBACK_TRANSACTION_QUERY WHERE XID = transactionID
Undo Transaction - Atomicity
Full Table
Undo Drop
Entire Database
Fine-grained access control available via Virtual Private Database feature
Query: Query data at some point in time in the past.
Versions Query: Retrieve all different versions of data between two points in time. Useful for seeing how and when data has changed.
Transaction Query: See all changes made by a transaction. Produce SQL code to undo the transaction.
Transaction: Undo a single transaction. Optionally undo dependent transactions as well.
Table: Recover one or more tables to a given point in time.
Drop: Restores a dropped table, including its indexes, constraints, and triggers from the dropped objects Recycle Bin. Saves the work of doing a restore then recreating all table attributes.
Database: Quickly restores a database to a specific point in time by only restoring the blocks that have been changed. A normal recovery would require the entire database to be restored.

5. Data Corruption Protection
Ex: Fault during single read/write operation
Two-Phase Commit
Prepare: Write to log and lock table
Commit: Write to disk if ready then log as committed
Prevent corruption by setting parameters
Wide range of backup options
RMAN (Oracle Recovery Manager)
Configure backup and recovery policy
Verify backups aren't corrupt
Fast recovery backup
Stored on disk onsite - secondary storage
Only the newest files are stored here
Tertiary (remote) backup
Backups are copied to tape or uploaded to Amazon S3
Data Recovery Advisor
Identifies the available recovery options
Temporary fault can be in file system, volume, device driver, storage controller, or disk drive.
Prepare phase: Each node can respond as prepared, read-only (data on node not changed by SQL statements to be committed), or abort. One abort aborts transaction.
Commit phase: Send message to all nodes asking them to commit.
Use DB_ULTRA_SAFE. Automatically enables checks for critical corruption: block header checks, full-block checksums, and lost-write verification
Backup to disk, tape, and cloud. Provides for recovery from multiple failure situations.
RMAN keeps history of all backup and recoveries and verifies all data blocks.
FRA includes RMAN backups, control files, archived logs, and data file copies. Old files should have been backed up to tape before being deleted.
Data recovery advisor helps save time reading through error files while preparing for recovery.

6. Storage Failure Protection
Ex: Disk drive crash
ASM (Automatic Storage Management)
Database-specific RAID
Block Repair
Automatically: relocate valid blocks from the mirrored copy
Manually: relocate specific blocks
Rolling Upgrades
Keeping application online while upgrading ASM
ACFS and ADVM
ASM Cluster File System
Extends ASM functionality to support all non-Oracle database files
ASM Dynamic Volume Manager
Provides a general purpose volume management platform for 3rd party file system

7. Standby database options
Site Protection
Ex: fire, storm, power outage
Oracle Data Guard options:
Standby database up-to-date
Standby database is a snapshot
Use standby to perform planned
maintenance in a rolling fashion
Oracle GoldenGate – Distributed databases
All databases are active for reading/writing
Oracle Streams
Standby database options
Site failures - natural disasters, power outages, communications outages, etc
Structure of distributed database

8. References
Oracle Database 11g Release 2 High Availability:
Using Oracle Flashback Transaction Query
Oracle Recovery Manager
Oracle Secure Backup
ASM in Oracle Database 10g
Oracle Data Guard 11g
Oracle GoldenGate 11g
Two-Phase Commit Mechanism