XTTS (Cross-Platform Transportable Tablespaces)

XTTS (Cross-Platform Transportable Tablespaces) is the Oracle technique for moving tablespaces between different platforms and database versions — for example from Oracle 11gR2 on Linux x86 to Oracle 19c on OCI — by physically transporting datafiles rather than performing a logical export/import. For databases in the terabyte range, this approach reduces the final cutover downtime from days to a few hours.

How it works #

The process is structured in three distinct phases:

1. RMAN level 0 backup — a full copy of the source tablespace datafiles, transferred to the destination and restored.
2. Cyclic incrementals (level 1) — run multiple times in the weeks before cutover, progressively shrinking the delta between source and destination.
3. Final cutover — the last incremental is applied with the source tablespace in read-only mode; plugging it into the destination completes the migration.

# Example: generating the RMAN script for a level 0 backup
$ORACLE_HOME/perl/bin/perl xttdriver.pl --backup_to_dest \
  --tablespaces USERS,FINANCE \
  --level 0

The xttdriver.pl script (available on Oracle MOS) orchestrates backup, endian conversion, and file transfer.

When to use it #

XTTS is the right choice when:

• The database exceeds a few hundred GB and a Data Pump export would require unacceptable maintenance windows.
• The migration crosses major versions (e.g. 11g → 19c) or platforms with different endianness.
• The SLA mandates a maximum downtime measurable in hours, not days.

The main drawback is operational complexity: it requires precise coordination between source and destination DBAs, character set compatibility checks, and separate handling of non-transportable objects (sequences, synonyms, grants) that must be migrated independently via Data Pump.