146 The Business Value of DB2 UDB for z/OS
Automatic secondary space allocation
Before Version 8, DBAs had to spend time manually resizing the amount of
disk space suballocated for table spaces. This enhancement allows the DBA
to instruct DB2 to manage all table secondary expansions autonomically.
Using DB2 UDB for z/OS Version 8, customers can now fully exploit the immense
storage capabilities of the 64-bit memory model with no changes to their
applications. This allows DB2 systems to cache significantly more data, allowing
it to vertically scale. Since the length of many DB2 objects, such as table, view
names, and column names, have increased, this additional storage could not
have come at a better time. The customer can combine data sharing, which
helps in scaling horizontally, and benefit from excellent availability, by being able
to scale vertically. Customers can expect some increase in CPU requirements
following the move to a 64-bit environment.
Backup and recovery
A quick backup and recovery implies more database availability. The tables of
packaged software generally have application enforced Referential Integrity (RI)
and rarely have database enforced RI. Therefore you cannot use the QUIESCE
utility to establish a point where the set of table spaces related to the referential
structures are in a consistent state.
To help the DBAs in such situations, DB2 Version 8 has introduced the BACKUP
SYSTEM utility, which can backup an entire subsystem or data sharing group.
Similarly you can recover the entire subsystem by using the RESTORE SYSTEM
utility. The BACKUP SYSTEM utility when used along with FlashCopy makes the
backup extremely fast and promotes database availability. You can learn about
this entire backup and recovery process on the DB2 for z/OS Version 8 Web site
Many features in DB2 UDB for z/OS Version 8 have enhanced performance.
Some of these features are explained in the following sections.
These are mentioned from an application development point of view in 6.2.4,
“Rapid development of high performance applications” on page 138. This section
discusses those SQL improvements that are performance related and were not