Shadow Instance Handling During The Upgrade

This topic deals with the setup and operation of the shadow instance that was installed in parallel to the productive instances. It involves the environment in which the kernel is operated during the upgrade.

Database Implementation

All basis tables are imported into the productive database schema with a specific shadow table name. These shadow table names are composed of the original table name and a question mark ? for the IBM i database and a tilde ~ for all other databases.

Then an additional user or schema is installed in parallel, under which the views are created for all the new SAP basis tables. These views can be implemented as database synonyms, aliases, or views. In addition, all other shadow objects (such as views or functions) are created for the system.

The views of the new basis tables on the shadow instance have the same name as the original table and refer to the shadow table of the user, schema, or database.

The connection for the kernel and the tools to the shadow instance is controlled as follows:

The environment variable auth_shadow_upgrade = 1 or profile parameter auth/shadow_upgrade = 1 switches the connection to the shadow system.
During the shadow operation, the kernel of the shadow Instance uses the synonyms, aliases, or views with the original names of the tables to access the shadow tables of the original database.
Do not configure or setup the connection to the shadow system manually. If necessary, the Software Update Manager takes care of the configuration

Kernel Directories

The Software Update Manager automatically starts the load of the shadow instance kernel from the directory <SUM directory>/exe

The directories for the shadow instance are <SUM directory>/system/<SID>/SYS/profile and <SUM directory>/system/<SID>/D<NR>/work.

The shadow instance has its own instance number message server, enqueue server, dispatcher, dialog process, batch process, and update process. The <SID> is identical to the one in the original system.

Starting the Shadow Instance

SAPup automatically starts the shadow instance in the START_SHDI_* phases. You can manually start or stop the shadow instance using the commands SAPup startshd or SAPup stopshd. See also Starting and Stopping the Shadow Instance Manually.

To lock or unlock the shadow instance, use the commands SAPup lockshd or SAPup unlockshd.

Logging on to the Shadow Instance

Follow the regular logon procedure when you log on to the shadow instance. However, you must specify the instance number of the shadow instance.

The user DDIC is created in the shadow instance by default in client 000. It has the same password as the user DDIC in client 000 in the original system.

The functions of the shadow instance are limited.