DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

9.4 Migration
– Use “Inactive DBAT” instead of “Type 1 Inactive Thread”
– Use “Inactive Connection” instead of “Type 2 Inactive Thread”
► CCSIDs must be specified for EBCDIC, ASCII and Unicode even when you do not use
those encoding schemas in your application
► The DSNHDECP module must be defined by the user. It is not defined by DB2 by default.
► Buffer pools BP8K0, BP16K0, and BP32K must be defined in advance since some catalog
table spaces use 8 KB, 16 KB and 32 KB pages.
► For data sharing groups: GBP8K0, GBP16K0 and GBP32K also need to be allocated.
► The location name must be specified, even if DDF is not used. See PTF UQ90701 for
APAR PQ91009.
Migration is the process of converting an existing DB2 subsystem, user data, and catalog
data to a new version. This process has changed from DB2 V7 to V8 in order to minimize the
possible impact of regression and fallback incompatibilities. For more information refer to DB2
UDB for z/OS Version 8 Installation Guide, GC18-7418.
The migration to DB2 V8 is only allowed from V7. As mentioned, a DB2 V8 subsystem will
migrate going through three different modes:
► Compatibility mode (CM)
► Enabling-new-function mode (ENFM)
► New-function mode (NFM)
We are interested in the performance of the catalog migration, how long the migration will
take, and how big the catalog will be. In this section we are using general information from
several real migrations to illustrate the catalog migration. After reading this section you will be
able to determine how long it is going to take to migrate your catalog and how large it will be
after the migration.
During the migration process, you must go through CM and ENFM, before reaching the NFM.
When in CM, your Catalog and Directory have already successfully been converted to V8,
new columns have been added to existing tables, new indexes and table spaces have been
created and so on.
However, there are two other major changes to the DB2 catalog necessary to make most of
the new functions provided with DB2 V8 possible. These changes are:
► Change existing catalog columns so that they can store long names.
► Convert the catalog to Unicode.
In CM, these two changes have not been done. Furthermore, the only new functions available
for use in this mode of operation are those which allow fallback to V7.
In ENFM, you are in the process of converting your Catalog table spaces so that after
completion of the conversion, they now accept long names and exist in the Unicode encoding
scheme. Catalog conversion is performed by running job DSNTIJNE. You can spread
conversion of your catalog table across several maintenance intervals. Use job DSNTIJNH to
direct DSNTIJNE to halt after conversion of the current table space has completed. To
resume, simply rerun DSNTIJNE from the top. It will automatically locate the next table space
to be converted. The process of conversion is not disruptive, that is, you can continue
operation while being in ENFM. Once you have migrated all table spaces of your DB2 catalog
to Unicode, your DB2 subsystem will operate in NFM once you run the DSNTIJNF to indicate
Chapter 9. Installation and migration 353