Hi Jeroen and Chris,
I totally agree with you about the risk of removing devices when it has already associated with a database, the reason of removing device comes from the user story of my product ( I believe it is just nice to have not require to implement in product ). There is a mechanism that allow user to define the scope of data range stored in database via month range, a device is organized with following structure: 1 device - 1 segment - 12 months partitions.
Let's assume that we have a device for year 2015 with above structure, and the retained months stored in database is 15 months. When we come to the last date of December of 2015, we need to create a new device for next year with same structure above to the data because the database uses month partition (everything is go smoothly here 
). After that user changes his mind, he decides to drop retained month(s) down to only 4 months. So we just need the second device for cycling use (drop old partitions and add new ones on the second device), the first device is redundant. That is the reason why I asked for removing device safely. Maybe we can re-use the first device when user increase the retained months. For conclusion, it's something that is nice to have , we can treat as limitation of Sybase
The real question is about capturing the database auto expansion event, there is some approaches from me and Pawel at the top of this topic, I'm working on it. If you have another suggestions, please share with me. Really Appreciate for your help.
Thanks
Khoa Tran