©Copyright IBM Corp. 1999 5
Chapter 2. Summary of Considerations
This book describes the exploitationof storage by DB2 for OS/390 (DB2). Two
major areas are analyzed:
1. DB2 and storage management
2. DB2 and storage servers
This chapter summarizes the major conclusions of thisproject.

2.1 DB2 and Storage Management

Adet ailed analysisof the different types of DB2 data sets shows that DFSMS can
automaticallym anageall of the data sets DB2 uses and requires. However,there
are considerations and choices that need to be made to tailor DFSMS to suit the
individual customer’ssystems environment and organization.
In general, a large percentage of your data sets can be managed with DFSMS
storage pools,t hus reducing theworkload and the interaction of your DB2
database administrators(DB As) and storageadm inistrators.Only the most
critical data, as defined with service levelagreements or as revealed by
monitoring, may requires pecialattention.

2.1.1 Benefits of DFSMS

Using DFSMS, theDB2 administrator gains the following benefits:
• Simplified data allocation
• Improved allocation control
• Improved performance management
• Automated disk space management
• Improved data availability management
• Simplified data movement
See 4.4, “Benefits” on page 32 for more details.
Another very important benefit is that, withD FSMS,the DB2 environment is
positioned to take immediate advantageof available and future enhancements.
For example,the following enhancements are availabletoday to DB2 with the
appropriate level of DFSMS:
•DFSMS1.4
• Space allocation failures are reduced with the support of a maximum
number of 255 extentsper c omponentof VSAM data set for multivolume
data sets (the limit is 123 data sets for a single volume allocation).
• Image copy with concurrent copy support for RAMAC Virtual Array
SnapShot.
•DFSMS1.5
• Support for 254 table space or index space partitions or pieces up to 64G B
with the use of VSAM Extended Addressability for Linear Data Sets; also
4,000 TB support for LOBs.