I routinely load and reload ~7 billion rows into oracle 11g, once every 5 months or so. It takes about 4 days, 20 days if you do something stupid like create the indexes before loading, although I think oracle can go quite a bit faster, and that 4 days is limited by processing and non-DB I/O.
We use oracle because the partitioning options are better and bitmapped indexes. (We wanted more partitions so we could use a hierarchical triangular mesh for point-radius searches)
MySQL can do a whole lot more then that too. I routinly get 15k to 20k writes per second while the server is under normal load. You can spike that a great deal higher depending on what else your doing and what kind of table your writing.
Dell X4240 with dual quad core opteron 2384 (2700Mhz), 64GB memory, 6TB disk space in RAID-5, I believe 10000RPM drives. Oracle partitions are set by week, then subpartitioned by hierarchical triangular mesh region (http://www.skyserver.org/htm/), and our data is inherently anisotropic. Block size is 4kb I believe.
We use oracle because the partitioning options are better and bitmapped indexes. (We wanted more partitions so we could use a hierarchical triangular mesh for point-radius searches)