CA ARCserve D2D, during the merge process applies the changed blocks of data from an incremental session to the previous full session to create a new full (or baseline) image. This process would help maintain the specified number of recovery points set by the user.
After the first full backup, CA ARCserve D2D would continue with incremental backups. After the limit is reached, 3 in the below example, CA ARCserve D2D would merge the oldest incremental into the parent (full) backup to create a new baseline image. After all the blocks from the oldest incremental are written into the parent backup, that incremental session will be purged (discarded).
In the below example the Recovery point limit is set to 3 that is why we have three child jobs, so at any point of time the maximum number of recovery points available will be three. The moment the 4th child job runs the oldest child job is merged to the parent full backup and the session will get purged. The maximum number of recovery points which can be set is 1344 and the default limit is 31.