How SMAPP works
The purpose of system-managed access-path protection (SMAPP) is to reduce the amount of time it takes to restart the system or vary on an independent disk pool, after an abnormal end.
It can take much longer than normal to restart the system when the system ends abnormally because of something like a power interruption. Also, if you are using an independent disk pool, the next vary on of the independent disk pool can take much longer than normal.
Access paths
An access path describes the order in which records in a database file are processed. A file can have multiple access paths, if different programs need to see the records in different sequences.
How SMAPP works with abnormal ends
When the system restarts after an abnormal end, the system rebuilds access paths that were open for updating at the time of the abnormal end. Rebuilding access paths contributes to this long restart time. Likewise, when you vary on an independent disk pool, the system rebuilds access paths that were open for updating at the time the independent disk pool ended abnormally. The system does not rebuild access paths that are specified as MAINT(*REBLD) when you create them. When protecting access paths with SMAPP, the system uses information that it has collected to bring access paths up to date, rather than rebuilding them.
You can specify the target time for rebuilding access paths after the system ends abnormally. The target time is a goal that the system does its best to achieve. The actual recovery time for access paths after a specific failure may be somewhat more or less than this target.
The target recovery time for access paths can be specified for the entire system or for individual disk pools. The system dynamically selects which access paths to protect to meet this target. It periodically estimates how long it will take to recover access paths that are open for change.
For new systems, the system-wide recovery time for access paths is 50 minutes, which is the default. If you move from a release that does not provide the SMAPP function to a release that supports SMAPP, the system-wide recovery time for access paths is also set to 50 minutes.