I am not sure if this question makes sense, but I have been tasked to find this out:
What is largest amount of writeable data that MySql can handle before croaking, if the frequency of writes to the same table is about 1 per second? Do we really need Oracle or its ilk to handle a 150 megabyte database that has some fairly light concurrent traffic inserting/updating the same very large table? What if we had 2 tables, one for users A to M and another for users N to Z (just an example, don't take me literally.)
The MySql would be running under Linux on an Intel Dual 1.5Ghz system with 1 GB memory, pretty fast RAID 5 disks.