Use Round Robin Databases-- they're made for high volume timeseries data. They're fixed in size, so they won't grow after you create them. They also support automatic rollup, so you could save 1 datapoint per second for 10 minutes, then save the average of 15 datapoints for the past day, etc.

Caveats:

1) You can't change the schema once you create the file. Adding new fields means adding a new file or recreating your existing file

2) With heavy I/O you may need to put these files on a RAM disk, and then periodically flush the persistency.