XTTS: Prerequisites

When migrating Oracle Database to a different endian format using transportable tablespaces and incremental backups (XTTS), a list of requirements must be met. The following list of requirements exist when using:

V4 Perl Script

The most important requirements – for a complete list check MOS note:

  • Windows is not supported.
  • RMAN on the source system must not have DEVICE TYPE DISK configured to COMPRESSED.
  • RMAN on the source system must not have default channel configured to type SBT.
  • For Linux: Minimum version for source and destination is 11.2.0.3.
  • Other platforms: Minimum version for source and destination is 12.1.0.2.
  • Disk space for a complete backup of the database on both source and target host. If your data files take up 100 TB, you need an additional 100 TB of free disk space. For 12c databases, and if your data files have a lot of free space, the backup might be smaller due to RMAN unused block compression.

Also worth mentioning is that the Perl script during the roll forward phase (applying level 1 incremental) will need to restart the target database. Applying the incremental backups on the target data files happens in NOMOUNT mode. Be sure nothing else uses the target database while you roll forward.

Block Change Tracking (BCT) is strongly recommended on the source database. Note, that this is an Enterprise Edition feature (in OCI: DBCS EE-EP or ExaCS). If you don’t enable BCT the incremental backups will be much slower because RMAN has to scan every single data block for changes. With BCT the database keeps track of changes in a special file. When RMAN backs up the database, it will just get a list of data blocks to include from the change tracking file.

What If – V3 Perl Script

If disk space is a problem or if you can’t meet any of the other requirements, check out the below two MOS notes:

They describe a previous version of the Perl script, version 3. The scripts use DBMS_FILE_TRANSFER to perform the conversion of the data files in-flight. That way no extra disk space is needed. However, DBMS_FILE_TRANSFER has a limitation that data files can’t be bigger than 2 TB.

Also, the V3 scripts might be useful for very old databases.

Transportable Tablespaces In General

To get a complete list of limitations on transporting data, you should look in the documentation. The most notable are:

  • Source and target database must have compatible character sets. If the character sets in both databases are not the same, check documentation for details.
  • No columns can be encrypted with TDE Column Encryption. The only option is to remove the encryption before migration and re-encrypt afterward.
  • TDE Tablespace Encryption is supported for same-endian migration if the source database is 12.1.0.2 or newer. If you need to go across endianness, you must decrypt the tablespaces and re-encrypt after migration. Remember, Oracle Database 12.2 can encrypt tablespaces online.
  • If you are migrating across endianness, you must convert the data files. You must have disk space to hold a copy of all the data files. In addition, you should perform the conversion on the platform that has the best I/O system and most CPUs. Typically, this is the cloud platform, which also offers scaling possibilities.
  • Requires Enterprise Edition.
  • The database timezone file version in the target database must be equal to or higher than the source database.
  • The database time zone must match if you have tables with TIMESTAMP WITH LOCAL TIME ZONE (TSLTZ). If you have such tables, and the database time zone does not match, those tables are skipped during import. You can then move the affected tables using a normal Data Pump table mode export and import. To check the database time zone:
    SQL> select dbtimezone from dual;
    
    You can alter the time zone for a database with an ALTER DATABASE statement.

Full Transportable Export/Import

FTEX automates the process of importing the metadata. It is simpler to use and automatically includes all the metadata in your database. Compared to a traditional transportable tablespace import, FTEX is a lot easier and removes a lot of manual work from the end user. But there are a few requirements that must be met:

  • Source database must be 11.2.0.3 or higher.
  • Target database must be 12.1.0.1 or higher.
  • Requires Enterprise Edition.
  • COMPATIBLE must be set to 12.0.0 or higher in both source and target database. If your source database is an Oracle Database 11g, this is not possible. In that case, set version to 12 or higher during Data Pump export instead.

If you can’t meet the requirements, check out traditional transportable tablespace. It have different requirements, and it allows more customization.

Other Blog Posts in This Series

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