Michel,
"Cache expiration", "DB2 & TSM data expiration" are two independent items when it comes to setting the expiration period. The "Life of Data & Indexes" in Application group "Storage Management" settings deals with "DB2 & TSM Data expiration". Cache expiration depends on the "number of days" you are setting up for expiration.
Starting with v8.4, both "Cache expiration" & "DB2 & TSM data expiration" are retroactive. Note that the expiration will depend on the load date when you don't have a date field which is defined as "segment" in the application group. If there's a segmentation date field defined in the application group, the expiration depends on this date field.
Data in cache is maintained in multiple filesystems based on the configuration done. cache1 filesystem contains softlinks to the compressed data objects available in other cache filesystems. It also, has expr and migr directories under it. In the expr directory, there will be sub-directories which have the names of dates in OD format. And these date sub-directories contain softlinks to CMOD compressed data objects. These date based directories are used for data expiration in cache once that date is reached.
TSM expiration depends on multiple factors. Please refer to
http://www.odusergroup.org/forums/index.php?topic=478.0DB2 & TSM expiration happens when you run the arsmaint -d. CMOD will wait for a confirmation from TSM that data is deleted and then only delete the data in DB2.
Feel free to ask more questions on this.
Sandeep Veldi