/rds-db2

RDS for Db2 — Mainframe Migration Reference

Source blogs:

• https://aws.amazon.com/blogs/database/migrating-tables-from-ibm-db2-for-z-os-to-amazon-rds-for-db2/
• https://aws.amazon.com/blogs/database/choosing-the-right-code-page-and-collation-for-migration-from-mainframe-db2-to-amazon-rds-for-db2/

z/OS to RDS Db2 — Overview

Migrating from Db2 for z/OS is a replatform (different OS/endianness). You cannot restore a z/OS backup image to RDS for Db2. The process requires:

1. Schema conversion (DDL extraction + transformation)
2. Data migration (export/load, federation, or replication tools)

Schema conversion (DDL)

Recommended tool: ADB2GEN (IBM Db2 Administration Tool for z/OS)

ADB2GEN extracts DDL for tables, indexes, views, triggers, check constraints, referential constraints, identity columns, sequences, and GRANT statements with high fidelity.

Python conversion script

A Python script converts ADB2GEN output to RDS for Db2 compatible DDL:

python zos_to_luw_ddl_conversion.py <zos_ddl_file> <target_schema> <target_data_tablespace> <target_index_tablespace> <output_file>

# Example:
python zos_to_luw_ddl_conversion.py EMPLOYEE.DDL SCHEMA1 TS_DATA_8K TS_INDEX_8K EMPLOYEE.out

What the script handles

Create tablespaces before running DDL

call rdsadmin.create_bufferpool('<DBNAME>', 'BP8K', 10000, 'Y', 'Y', 8192);
call rdsadmin.create_tablespace('<DBNAME>', 'TS_DATA_8K', 'BP8K', 8192);
call rdsadmin.create_tablespace('<DBNAME>', 'TS_INDEX_8K', 'BP8K', 8192);

Code page and collation selection (summary)

Code page, collation, and territory are immutable after database creation, so choose them before you create the target database with rdsadmin.create_database(name, pagesize, codeset, territory, collation). Quick mapping:

Watch-outs: UTF-8 expands accented characters from 1 to 2 bytes (truncation risk — consider CODEUNITS32), and ISO-8859-1 silently substitutes out-of-range characters with 0x1A.

For full code page and collation guidance, see code-page-collation.md — the CCSID inventory, the complete decision matrix, rdsadmin.create_database examples, CODEUNITS32 vs OCTETS trade-offs, and source-CCSID checks.

Data migration tools for z/OS

Db2 Federation (RDS → z/OS)

RDS for Db2 supports homogeneous federation. Catalog the z/OS database from within RDS, then load data directly:

-- Catalog the z/OS server in RDS
db2 catalog tcpip node ZOSNODE remote <zos-host> server <port>
db2 catalog database <zos-dbname> as ZOSDB at node ZOSNODE

-- Load from z/OS cursor into RDS table
LOAD FROM (SELECT * FROM ZOSDB.<schema>.<table>) OF CURSOR INSERT INTO <rds-schema>.<table>

Mainframe tools workflow

1. Extract data using HPU/File-AID/UNLOAD in DEL or IXF format

2. Convert EBCDIC → ASCII (mainframe tools or iconv)

3. Copy to S3 using AWS CLI on mainframe (Go SDK for AIX where CLI unavailable)

4. Load into RDS from S3:

   CALL SYSPROC.ADMIN_CMD('LOAD FROM DB2REMOTE://myS3/<path/to/file.ixf> OF IXF INSERT INTO <schema>.<table>');

Best practices for mainframe migration

1. Run precheck on source before the final backup (see migration.md).
2. Choose code page early — immutable after database creation.
3. Use IXF format — avoids delimiter conflicts, preserves types.
4. ADB2GEN for DDL extraction — highest fidelity for z/OS.
5. Test character round-trips — insert international chars, export, import, verify display.
6. Large tables: Db2 federation or S3 load for bulk, then CDC via Qlik/Precisely/Q Replication.
7. Cold data early; hot data near cutover.
8. Validate with DBeaver / DataGrip / IBM Data Studio for character display consistency.