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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Checking Exception Files for Uncommitted
Transactions
primary database to the exact same state that the backup database was in when the
takeover operation completed.
You then configure the RDF subsystem to run from the backup to the primary system
to bring the primary database back up to date with updates that took place while the
primary was down.
When the primary database is fully current, you then perform a planned switchover
from the backup to the primary system, and restart your applications on the primary
system.
If the purger issues an 858 event message, file recovery on the primary system is not
possible.
Checking Exception Files for Uncommitted Transactions
Exception files are used by updaters to store information about each audit record that
the updater undoes during the three possible undo passes. An exception record logs
information about a specific audit record that the updater has undone. This may or
may not be useful information for you. If the volume of audit is small, then logging an
exception record for each record undone may have only a slight performance impact
during the takeover operation. If, however, the volume of audit to be undone by an
updater is large (e.g thousands of records), then logging an exception record for each
record undone could have an impact on the takeover operation.
You can choose whether you want exception records for each transaction when you
configure the RDF UPDATEREXCEPTION attribute. If you set it ON, the updater logs
an exception record for each audit record on which it executes undo. If set OFF, then
an exception record is only written for the first and last audit records undone. Please
note that if you set UPDATEREXCEPTION OFF, you can still determine which
transactions were undone by using the READLIST utility to read the undo files.
Your database administrator can use the RDFSNOOP utility to examine exception
records in exception files. See Appendix B, Additional Reference Information for
information about RDFSNOOP.
Note. You always use the logged MAT position from the 888 event message to initiate the file
recovery operation, even if the RDF configuration is replicating auxiliary audit trails.
Caution. The absence of exception file records after a successful takeover operation does not
necessarily indicate that the backup database is logically identical to the primary database. It is
possible that no audit data reached the backup system for some transactions committed on the
primary system. That is, the transaction was started and committed, but the primary system
failed before the associated audit was transmitted to the backup system.