A method and apparatus for erase operations of a flash memory block. A request to write data to the storage system is received and the data is written to the set of one or more solid state storage devices in response to receiving the request. The submersible pump includes a first chamber and a second chamber that are parallel in manner and substantially hollow. The thrust force imparted to the drill string is adjusted in response to the computed yield point. 1where A, B, R1, R2, R3, R4, R5, R6 and k are as defined herein.