RDF System Management Manual
Table Of Contents
- RDF System Management Manual
- What’s New in This Manual
- About This Manual
- 1 Introducing RDF
- RDF Subsystem Overview
- RDF Processes
- RDF Operations
- Reciprocal and Chain Replication
- Available Types of Replication to Multiple Backup Systems
- Triple Contingency
- Loopback Configuration (Single System)
- Online Product Initialization
- Online Database Synchronization
- Online Dumps
- Subvolume- and File-Level Replication
- Shared Access DDL Operations
- EMS Support
- SMF Support
- RTD Warning Thresholds
- Process-Lockstep Operation
- Support for Network Transactions
- RDF and NonStop SQL/MX
- Zero Lost Transactions (ZLT)
- Monitoring RDF Entities With ASAP
- 2 Preparing the RDF Environment
- 3 Installing and Configuring RDF
- 4 Operating and Monitoring RDF
- 5 Managing RDF
- Recovering From File System Errors
- Handling Disk Space Problems
- Responding to Operational Failures
- Stopping RDF
- Restarting RDF
- Carrying Out a Planned Switchover
- Takeover Operations
- Reading the Backup Database
- Access to Backup Databases in a Consistent State
- RDF and NonStop SQL/MP DDL Operations
- RDF and NonStop SQL/MX Operations
- Backing Up Image Trail Files
- Making Online Dumps With Updaters Running
- Doing FUP RELOAD Operations With Updaters Running
- Exception File Optimization
- Switching Disks on Updater UPDATEVOLUMES
- 6 Maintaining the Databases
- 7 Online Database Synchronization
- 8 Entering RDFCOM Commands
- 9 Entering RDFSCAN Commands
- 10 Triple Contingency
- 11 Subvolume- and File-Level Replication
- 12 Auxiliary Audit Trails
- 13 Network Transactions
- Configuration Changes
- RDF Network Control Files
- Normal RDF Processing Within a Network Environment
- RDF Takeovers Within a Network Environment
- Takeover Phase 1 – Local Undo
- Takeover Phase 2 – File Undo
- Takeover Phase 3 – Network Undo
- Takeover Phase 3 Performance
- Communication Failures During Phase 3 Takeover Processing
- Takeover Delays and Purger Restarts
- Takeover Restartability
- Takeover and File Recovery
- The Effects of Undoing Network Transactions
- Takeover and the RETAINCOUNT Value
- Network Configurations and Shared Access NonStop SQL/MP DDL Operations
- Network Validation and Considerations
- RDF Re-Initialization in a Network Environment
- RDF Networks and ABORT or STOP RDF Operations
- RDF Networks and Stop-Update-to-Time Operations
- Sample Configurations
- RDFCOM STATUS Display
- 14 Process-Lockstep Operation
- Starting a Lockstep Operation
- The DoLockstep Procedure
- The Lockstep Transaction
- RDF Lockstep File
- Multiple Concurrent Lockstep Operations
- The Lockstep Gateway Process
- Disabling Lockstep
- Reenabling Lockstep
- Lockstep Performance Ramifications
- Lockstep and Auxiliary Audit Trails
- Lockstep and Network Transactions
- Lockstep Operation Event Messages
- 15 NonStop SQL/MX and RDF
- Including and Excluding SQL/MX Objects
- Obtaining ANSI Object Names From Updater Event Messages
- Creating NonStop SQL/MX Primary and Backup Databases from Scratch
- Creating a NonStop SQL/MX Backup Database From an Existing Primary Database
- Online Database Synchronization With NonStop SQL/MX Objects
- Offline Synchronization for a Single Partition
- Online Synchronization for a Single Partition
- Correcting Incorrect NonStop SQL/MX Name Mapping
- Consideration for Creating Backup Tables
- Restoring to a Specific Location
- Comparing NonStop SQL/MX Tables
- 16 Zero Lost Transactions (ZLT)
- A RDF Command Summary
- B Additional Reference Information
- C Messages
- D Operational Limits
- E Using ASAP
- Index
Managing RDF
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Reading the Backup Database
Note that if you have an RDF Network, there are some situations where File Recovery
with the TOMATPOSITION option is not possible. If that is the case, RDF logs an RDF
Event 858 at the end of the takeover operation.
Offline Method of Resynchronizing the Primary Database
When the failed primary system is restored to operable condition, you can take the
following steps to restore the original RDF configuration and make the old primary
database the current primary database again (where \A is the old primary system and
\B is the old backup system):
1. Stop the applications and TMF on \B.
2. Save the database on \B to tape.
3. Restart the applications and TMF on \B.
4. Initialize RDF on \B to the shutdown timestamp generated in Step 1.
5. Configure RDF to go from \B to \A.
6. Start RDF (\B to \A) with update off.
7. Restore the database on \A.
8. Turn on updating.
9. When RDF has caught up, do a planned switchover from \B to \A (as described
earlier in this section).
Reading the Backup Database
Unlike databases protected by TMF, backup databases for RDF protection have no
locks on rows or records, even while these rows or records are being updated.
Therefore, applications can read the backup databases at any time; the data can,
however, be inconsistent because reading and updating can occur simultaneously.
Except immediately after a takeover operation, after the updaters have stopped as the
result of a STOP TMF command, or after the updaters have stopped as the result of a
STOP UPDATE, TIMESTAMP command (discussed in the next topic, below), you only
have the equivalent of BROWSE ACCESS to the backup database. BROWSE
ACCESS, a NonStop SQL/MP access option for transaction consistency, provides
immediate access to the data; however, the data can be inconsistent because a
transaction might not be completely applied to the backup database when the query is
in progress. This access provides the lowest consistency but the highest concurrency.
Immediately after a takeover operation or after the updaters have stopped as the result
of a STOP TMF or STOP UPDATE, TIMESTAMP command, you have the equivalent
of STABLE ACCESS to the backup database; at those points, the backup database is
consistent with regard to all transactions whose outcomes (commit or abort) are known
at the backup system.