Availability Guide for Application Design

Data Protection and Recovery
Availability Guide for Application Design—525637-004
4-18
Database Management and Availability
to two locations. The application is more complex to develop and throughput might be
reduced while waiting for ready-to-commit messages from remote sites.
Database Management and Availability
This subsection introduces the features of NonStop SQL/MP that eliminate or reduce
downtime of the database or of the SQL programs that access the database. Note that
NonStop SQL/MP is not the only database manager available on HP NonStop
Systems; you can also use the Enscribe software, which is part of the HP NonStop
operating system.
Reorganizing and reconfiguring databases are briefly discussed here. Another set of
database design issues relates to running batch-type operations concurrently with
online operations. Refer to Eliminating Batch Windows on page 4-24 for some
guidelines.
Two Database Managers: NonStop SQL/MP and Enscribe
The NonStop SQL/MP product is a relational database manager. It manages data in
tables and indexes. The tables and the indexes can be partitioned across a set of files
that can be anywhere on the local or wide-area network. Each index is B-tree, which is
an associative file structure that provides keyed and key-sequenced access to data. A
catalog on each node keeps track of files that make up each table. For a complete
introduction to the NonStop SQL/MP product, refer to the Introduction to NonStop
SQL/MP.
The Enscribe database record manager is a database management software product
that provides a record-at-a-time interface between server processes and a database.
Refer to the Enscribe Programmers Guide for details on using this interface.
Reorganizing a Database While Avoiding Application Downtime
Databases organized as B-trees can be reorganized using the FUP RELOAD
command without taking the database offline. Key-sequenced Enscribe files and
NonStop SQL/MP tables and indexes can be reorganized in this way.
As data records are added and deleted in an Enscribe file or as rows and columns are
added and deleted in a NonStop SQL/MP table, database access becomes inefficient.
Reorganizing the file or table using the FUP RELOAD command restores efficient
access. Refer to the File Utility Program (FUP) Management Programming Manual for
details.
Reconfiguring a NonStop SQL/MP Database While Avoiding
Application Downtime
Your SQL database can be protected against unplanned outages by mirrored disks and
disk process pairs as described in Section 2, Overview of Server and Network Fault