HDD Read ahead
After execution of the command the hard disk drive magnetic head keeps "soaring" over the track from which the information has been requested and the HDD electronics continue to read out the information, sending it to the random access memory (buffer). Receiving command to start reading the hard drive firmware examines the buffer for requested sector and if the latter is present, the firmware transfers it to the computer with the maximum interface speed. As the sectors belonging to one file are usually on one and the same track, the technology of read ahead allows accelerating the access to the information. The increase in the size of the random access memory improves the efficiency of the given technology, while the high density of record, casual data access and reading of the big files decreases it.