Sometimes people comes to me and ask what is the HHD. This question is now coming more frequently. And hence now I am summing here what I know about these HHDs.



Traditional Hard drives
Traditionally, we use magnetic hard drive which uses moving parts to save data that is called  platters. Hard disk is a non -volatile data storage device ie. that data remains there even if there is no power. Traditional hard disk drive have  small flash memory, namely buffer (randing from 2mb-16mb) which stores frequently used data so that can make access faster. But traditional buffer memory is volatile, as soon as power goes, data is gone.

Hybrid Hard drives
The idea of buffer is further modified and hence these new hard drive evolved namely HHD, they are also called as ReadyDrive the technology made to utilize HHDs by windows Vista.
So real working is that apart of traditional storage of method, non-volatile flash storage is also included in hard drives. This way frequently accessed data get retrieved fast as well saving energy too.

Working
Working is simple, HHDs remain idle for most of the time. The data which comes get stored in buffer ie. flash memory and when it get full then it get transferred to Platter ie. harddrive's main storage and again Flash memory is freed up. This way very less amout of Hard drives physical activity is required thus saving energy  and time too.

Conclusion
Benefits for using such drive will include faster access time, saving of energy resulting in increased performance of various application. This technology is still in state of evolution though HHDs are available in market but not really popular yet.

Though this technology seems promising, it has few drawbacks too, like increased cost of hardware, because flash memory is costly so it will increase cost of hard drive too.
It is said that as hard drive to spin again and again when data stored on hard drive (ie. non cached ) is accessed then will increase seek time also for non cached data.

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