Availability Guide for Application Design

Data Protection and Recovery
Availability Guide for Application Design—525637-004
4-12
Interface on an HP NonStop System
Interface on an HP NonStop System
For requester, server, or monolithic programs (programs that combine requester and
server features) that execute on an HP NonStop system, you can access the
transaction control features of TMF through the TMF program interface from the
following supported languages: COBOL85, COBOL, NonStop SQL/MP, C, TAL, and
Pascal. Table 4-3 on page 4-11 lists the statements for each language to start, commit,
or abort a transaction.
Duplicate Databases
The data-protection methods discussed so far offer little protection against total site
failure. Major environmental catastrophes such as earthquake, flood, fire, or explosion
can destroy data on even the best-designed fault-tolerant systems.
For installations that cannot afford outage even in the most extreme of environmental
conditions, maintaining a duplicate database at a remote site provides the fastest way
of getting the application up and running again. Refer to the Introduction to NonStop
Operations Management for details on preparing a remote site.
A duplicate database can also provide backup during planned downtime of the primary
system or in the unlikely event of a multiple-point failure in the primary system such as
both halves of a mirrored disk failing.
This subsection discusses two approaches to maintaining duplicate databases:
•
Using one of the Remote Duplicate Database Facility (RDF) products
•
Performing every transaction against each copy of the database
Table 4-4. Programmatic Interface to Transaction Control Facilities on an HP
System
Function... In the language... Is provided by the statement...
To start a
transaction
COBOL85
NonStop SQL/MP
C, TAL, Pascal
ENTER TAL BEGINTRANSACTION
BEGIN-TRANSACTION
BEGIN WORK
BEGINTRANSACTION
To commit a
transaction
COBOL85
NonStop SQL/MP
C, TAL, Pascal
ENTER TAL ENDTRANSACTION
END-TRANSACTION
COMMIT WORK
ENDTRANSACTION
To abort a
transaction
COBOL85
NonStop SQL/MP
C, TAL, Pascal
ENTER TAL ABORTTRANSACTION
ABORT-TRANSACTION
ROLLBACK WORK
ABORTTRANSACTION