Identifying Unallowed Table Accesses in the Upgrade Subsystem

This section explains unallowed table accesses in the upgrade subsystem during the execution of a Zero Downtime Option (ZDO) maintenance event.

The upgrade subsystem must only perform changes on tables that are cloned. All tables that are classified as shared tables must not be changed by the upgrade subsystem. Structural changes cannot be kept unidentified as the table classification algorithm in phase RUN_RSPTBFIL_ZDM_CLASSIFY calculates the delta between source and target structure of all tables known in the ABAP Data Dictionary. Hence, no unallowed table access can happen by a structural change.

However, if table content in shared tables is changed from the upgrade subsystem, the upgrade procedure detects an unallowed table access and the transaction fails.

Note

Technically, the write access on shared tables from the upgrade subsystem is prevented. If a write access on such a shared table happens, a short dump occurs. This ensures that the bridge subsystem running does not see data that belongs to the target release written by the upgrade subsystem.

This image pictures the different table classifications that can occur in a ZDO run and shows with an arrow what an unallowed table access is. On top and below two bars indicate the bridge and the upgrade schema. When the upgrade accesses a shared table, this is called an unallowed table access which needs to be examined by SAP.

Unallowed table access can happen in different ways:

An application-defined procedure (AIM, XPRA, or XCLA) tries to write into a table that is not declared in the ZDO enablement.
Someone logged on to the upgrade subsystem and performed manual activities.

In both cases, the unallowed table access is recorded in an internal control table. At the end of the ZDO procedure, shortly before restarting the system, Software Update Manager checks if unallowed table access happened. If Software Update Manager finds unallowed table access, the phase RUN_ZDM_AIM_TRACE_CHECK_SANDBOX will stop with an error that cannot be skipped and an incident at SAP is required.