Can anyone help me understand the differences between SSD , SAS and SATA storages ?

Solid-state drive (SSD): It refers to a solid-state disk well defined as a data storage device that uses electric circuits as memory to store data in a stable manner. In this way, the stored data remains undamaged even when electricity is removed from the drive. SSD drives utilize compatible interface technologies similar to traditional block I/O hard drives such as SATA/SAS drives. In comparison to traditional hard drives, SSD drives are less exposed to physical shock and deliver greater performance. Unlike traditional hard drives, SSD drives do not include any type of moving mechanical components.

Serial ATA (SATA): This device has swapped the standard parallel ATA or commonly known as IDE drives. IDE or Integrated Drive Electronics means the disk control electronics is positioned on the drive itself. It allows newer hard drives to be able to switch out more easily or even to be utilized on different computers and with uncomplicated access to the data. SATA drives spin rate ranges between 5400-7800 RPM with data transfer rates up to 3/GS (gigabits per second). SATA drives are extensively used and popular in the market today due to their largest drive capacities. SATA drives today range up to two (2) Terabyte capacities and continue to grow

Serial Attached SCSI (SAS): Such drives have replaced traditional SCSI drives, which utilize the enterprise SCSI command sets for advanced functions. The SAS drives usually have much higher spin rates usually ranging between 10,000 to 15,000 rpm as well as provide faster access time. A key difference is that SAS includes better device consistency and enhance performance for data access read and write. Drive reliability is a major factor as SAS drives have a much greater mean time between failures (MTBF).

The key factor in determining which type of Hard disk drive is required for a new server depends on estimated usage of the server. Three key metrics including speed, reliability and storage capacity requirements will conclude the cost.