BW Archiving - Delete step

I have a question about how the delete is handled after the write of the archive files has taken place.

I am archiving data from a very large DSO. (160Gig).

I am archiving one year at a time. 2010 and 2009 worked fine.

When I archived 2008, the system tried to handle the delete in a very different way. Rather than using a selective delete, the job tried to copy the entire table excluding the archive criteria. I guess after than it would drop the table and then reload it. But the table is 160, so the transaction log filled up and the system crashed.

Is there a threshold? i.e. if the number of records to be archived is less than a certain value in the delete is handled by a normal selective delete, but if the number of records to be archived is higher than the threshold then it copies the table excluding the records to be deleted, drops the table and reloads it from the copy?

If this is the case, can this be turned off? i.e. force the system to use the selective delete only