Incremental Conversion during Release Upgrade

SAP Upgrades invariably lead to changes in the structure of database tables. Sometimes, this means that a complete restructure is necessary, with the conversion of each row in the table. In previous SAP Releases, this conversion occurred during upgrade downtime, so increasing that downtime. Incremental table conversion with transaction ICNV now lets you perform conversions before the upgrade, that is, during production operation.
Benefits

• Reduced downtime during upgrade
• Conversion of large tables during production operation

Features

• During the "prepare" phase of the upgrade, the system checks whether transaction ICNV can run with your database.
• If so, the system identifies all tables that might benefit from incremental conversion. For example, this includes tables containing large amounts of data, which would considerably extend the downtime of the upgrade.
• This all takes places automatically without any extra work.

Execution
If you have tables that might benefit from incremental conversion, then the system asks you in phase ICNVREQ to start transaction ICNV, leading to the following:
The system asks you:

1. Which modified tables you want to incrementally convert back to the standard SAP table definition
2. Which non-modified tables you want to incrementally convert

Steps

1. SAPup will prompt you to start ICNV during the Upgrade process
2. Start the incremental conversion (Login with TCODE ICNV)
3. Select Tables for Incremental conversion
4. Start Initialization followed by Data Transfer
5. Monitor the ICNV progress
6. Monitor the ICNV process & the DB growth closely. ICNV requires additional resource usage of the database, as well as a sufficient number of background work processes. It is also recommended that you execute ICNV as early as possible. This requires more careful planning.
7. Continue Upgrade process once 95% to 100% conversion is done for all the tables in list.

The system estimates the time taken for the conversion, so helping you to plan the start of the upgrade. Large tables are converted during uptime but the switch to the new structure is made only during downtime(PARCONV_UPG).
The procedure is designed to not be overly complicated and is fully integrated into the upgrade process. The conversion process is executed during uptime. The database load is expected to be higher during this process and therefore, it is possible to define exclusion times during which no ICNV processes are running. The conversion process calculates the estimated end of the process. This information helps you plan the upgrade timings.
The conversion is completed during upgrade downtime in phase PARCONV_UPG. Since most of the conversion has already been done, the downtime is significantly reduced.
Learning's
Do not attempt to modify tables that are being incrementally converted. These tables are locked until the end of the upgrade, so updates (including transaction SE11) are not possible.
Observe the resource usage of the database so that you can spot bottlenecks early on. You might have problems because extra space is required, as each converted table has to be replicated before conversion
Make sure that enough batch work processes are available, preferably one batch work process for each table to be converted. If you are converting a large number of tables, transaction ICNV distributes the tables to the available batch work processes.
Only start the upgrade when at least 95% of tables have been converted. This means that you have the greatest possible advantage in reducing downtime.