Availability Guide for Application Design

Availability Guide for Application Design—525637-004
4-1
4 Data Protection and Recovery
The database-related products introduced in this section provide protection of your
data not only if a single component fails, but also in the unlikely event of multiple
component failure, system failure, or even catastrophic site failure. You can also
protect your data against possible corruption due to concurrent access by
simultaneous online transactions or by contention between online transactions and
batch-mode operations. Protection mechanisms secure your data whether the data is
stored on disk in regular NonStop Structured Query Language/MP (NonStop SQL/MP)
files or Enscribe files, or in the form of queued messages.
Data-protection features provided by products such as Transaction Management
Facility (TMF), NonStop SQL/MP, Remote Duplicate Database Facility (RDF), and the
Queue Manager can help solve the following availability issues:
•
Ensure concurrent access to your data while maintaining data integrity.
•
Prevent incomplete transactions from invalidating your data.
•
Avoid loss or corruption of data due to multiple failures.
•
Avoid loss or corruption of data due to environmental catastrophe.
•
Avoid application downtime due to environmental catastrophe.
•
Keep a client/server application running (with reduced function) when a server
temporarily becomes unavailable.
•
Avoid application downtime due to batch windows.
This section provides an overview of HP’s transaction management and resource
management facilities related to data integrity. It explains how they solve the problems
listed above. These products and features include:
•
The TMF product, providing isolated transactions, recovery, and programmer
interfaces
•
The Remote Duplicate Database Facility (RDF) products, providing support for
current backup databases at remote sites
•
HP database management tools: the NonStop SQL/MP product, Enscribe
software, and the NetBatch-Plus batch processing product
•
The Queue Manager, providing transaction-protected access to files containing
queues of requests
This section discusses the availability features of these products.
Transaction Protection
The TMF product assists availability by providing transaction protection, database
consistency, and rapid database recovery. Working with any of HP’s transaction
monitoring products, TMF ensures availability without the application programmer