Once the TADz usage import runs, does it delete old data or keep it in the database?
The Usage import does not delete old data. HSISUDEL is the Usage Deletion job and it needs to be run on a periodic basis.
From Chapter 3. Installing and customizing IBM Tivoli Asset Discovery for z/OS of the TADz Admin & Reference guide, under "Maintaining the Production Repository Database":
You must perform regular maintenance tasks on the production Repository database to ensure that performance is optimal. The maintenance tasks cull obsolete and unwanted data and reorganize the database as necessary.
About this task:
A database administrator or system programmer performs these maintenance
1. Run the following jobs on a regular basis to delete old usage data, save space, and improve processing time:
a. Run the HSISUDEL job to delete usage data that are older than a specified period. b. Run the HSISUSUM job to summarize usage data and compress records into monthly periods.
2. Run the HSISLDEL job to delete obsolete discovery and usage data for a specified system (LPAR).
3. Run the HSISTPRM job to reset the status flag back to normal for tables in the production Repository database, following a failure.
4. Run the following jobs on a regular basis to maintain the integrity and performance of data in the production Repository database:
a. Run the HSISUT01 job to backup the Repository database in DB2 or backup the zFS file system in SQLite.
b. Run the HSISUT02 job to restore the Repository database in DB2 or restore the zFS file system in SQLite.
c. Run the HSISUT03 job to reorganize the Repository database in DB2.
d. Run the HSISUT04 job to update Runstats statistics for the Repository database in DB2.
Note that the HSISUDEL utility parameters (KEEPDETAIL, FIRSTDATE & LASTDATE) can only be modified to indicate YEAR & MONTH.