Derby - How Scalable?

[Rick Strong]

I've been using Cloudscape for quite a while in an application that 
hardly exercises it to its limits - relatively small amounts of data, 
few time critical functions, etc.. I gather that IBM is positioning 
Cloudscape as something of an entry-level product that one might migrate 
from when demands become too great, and move to DB2. As I'm preparing to 
move from an old version of Cloudscape to Derby, I'm wondering if Derby 
might actually be able to to accommodate larger datasets and support 
faster access than its positioning might suggest. This will be a servlet 
based system with up to ~100 concurrent users, each reading/writing data 
in 5-10K byte chunks every few seconds - this needs to be done in a 
timely manner. I'm not sure yet what our size limit on accumulated data 
would be, but bigger would of course be better.

Are there any opinions as to whether such a system might need to abandon 
Derby in favor of DB2 or something else, and if so what the approximate 
limits are? All opinions welcome.

Rick Strong