SQL Remote User's Guide
Administering SQL Remote for Adaptive Server Enterprise
Adaptive Server Enterprise transaction log and backup management
The Adaptive Server Enterprise log transfer interface allows the Message Agent to scan the Adaptive Server Enterprise transaction log. When this interface is being used, it sets a truncation point in the transaction log. The truncation point prevents Adaptive Server Enterprise from re-using pages in the transaction log before they have been scanned by SSREMOTE. For this reason, DUMP TRANSACTION will not necessarily release transaction log pages that are before the oldest open transaction. DUMP TRANSACTION will not release transaction log pages beyond the "truncation point".
The SQL Remote setup script (ssremote.sql) initializes the truncation point with the following command
dbcc settrunc( 'ltm', 'valid' ).
The truncation point can be reset with the following command
dbcc settrunc( 'ltm', 'ignore' ).
This command tells Adaptive Server Enterprise to ignore the truncation point, allowing transaction log pages beyond the truncation point to be released for reuse. You should only use this command when you are no longer interested in SQL Remote replication with the database and you want to be able to reclaim space in the transaction device with DUMP TRANSACTION commands. Continuing to run SQL Remote after ignoring the truncation point will fail to replicate any transactions that were in transaction log pages that were not scanned by the Message Agent and were freed by DUMP TRANSACTION.