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
HP NonStop RDF System Management Manual—524388-003
5-8
Processor Failures
Processor Failures
All RDF processes other than RDFCOM run as process pairs. If a CPU failure causes
a primary RDF process to fail, the backup process takes over without interruption in
service.
If any RDF process pair stops unexpectedly, the monitor sends abort messages to the
other RDF processes in order to bring about an orderly shutdown of RDF. You can then
restart the subsystem by merely issuing a START RDF command.
The subtopics that follow discuss how RDF responds to extractor, receiver, updater,
and RDF state transition failures.
Extractor Failure
Although the extractor runs as a process pair, the primary process does not maintain
restart information nor checkpoint this information to its backup. Instead, the receiver
maintains all restart information for the extractor, ensuring that the extractor is
restartable. The restart point is based on the audit trail position of the last record stored
in the image trail on the backup system.
If the extractor process pair inadvertently stops, you can (as stated above) restart the
RDF subsystem by merely issuing a START RDF command.
If the primary CPU of the extractor process fails, the backup extractor process requests
from the receiver a new starting position in the audit trail, ensuring a correct restart
position. This extractor-receiver protocol also provides protection against messages
from the extractor erroneously arriving out-of-order: if a message arrives out-of-order,
the receiver simply directs the extractor to restart.
When the CPU that failed comes back up, RDF switches the extractor to run on the
reactivated primary CPU.
Note. If the monitor process pair unexpectedly stops (for example, as in a double CPU failure),
you must stop the other RDF processes manually and then restart the subsystem. The easiest
way to do this is to issue a series of commands of the following form: STATUS *,PROG RDF-
software-loc.procname, STOP. The following command provides an example:
STATUS *, PROG RDF-software-loc.RDFUPDO, STOP
The RDF-software-loc could, for example, be $SYSTEM.RDF. Note that issuing this
command in this situation is only safe, however, if this is the backup system for a single RDF
environment. Alternatively, after stopping the extractor, you can stop all updaters and the
receiver on the backup system by issuing a STOP RDF command on the backup system.
Caution. During the interval between loss of the extractor and RDF subsystem restart, you
should not add any disk volumes to the RDF configuration (with the ADD VOLUME command).