The Standard Serial ATA or SATA (Serial Advanced Technology Attachment), allows you to connect to a compatible device motherboard (mass memory, DVD player, etc.). It notably specifies a data transfer format and a wire format.
Serial ATA has multiple benefits compared to its predecessor, the main three being its flow, cable management and the hot plug.
The old ATA standard is commonly referred to as Parallel ATA (P - ATA).
The first Serial ATA models, appeared in 2003 allow a theoretical rate of 1.5 Gbit/s, but have been designed to go much faster. The Serial ATA II double its flow to 3 Gbit/s and SATA III 6 Gbps appeared in 2009.
The theoretical throughput of 1.5 Gbps corresponds to 187.5 MB/s; in practice, it does not exceed 150 MB/s, which is only 17 MB/s more than the fastest of the Parallel ATA : the ATA/133.
Main advantages of SATA compared with the PATA :
-The PATA shares the same slick data with another device, which potentially reduces the bandwidth of each of 50%
-The water of the SATA interface is much easier to use, and place, than the POWA of the fact of its small size.
-Parallel buses now have difficulties to raise their rates because of a problem of synchronization of the data lines. Serial ATA uses the new LVDS for signalling.
-For multiple hard disks, in SATA, each disk has the maximum allowed by its standard and the controller. The SATA II standard allows the use of port multipliers.
SATA II standards (practical peak flow ~ 300 MB/s) and SATA III (practical peak flow ~ 600 MB/s) become useful for applications between several SSD, which flows begin to exceed the 400-500 MB/s for the high-end models early 2012.
|2||A + (transmit)|
|6||B + (receive)|
Cables and connectors
The biggest change compared to the Parallel ATA is located in the physical appearance of the cables used. Data are transmitted in 2 pairs (one pair for transmission) and one for the reception, protected by 3 ground wires. These seven drivers being grouped on a flat, flexible, tablecloth with 8 mm at each end connectors.
It can reach a length up to 1 meter. Compared to the short (45 cm) cable of 40 or 80 wires Parallel ATA, air flow, and therefore the cooling of equipment, is improved by this smaller width of cable. The concept of master/slave between the devices report has been abandoned.
Serial ATA has only one device per cable (point-to-point connection). The connectors have the notches, so it is not possible to put connectors of cable backwards. Some cables are equipped with locking. The absence of locking can cause unexpected disconnection in case of manipulation, which is strongly discouraged anyway. The same physical connectors are used for hard disks of 3.5 and 2.5 inches as well as desktop PC's internal CD/DVD writers and readers.
Serial ATA uses coding 8B / 10B to make transfers, allowing to work on better frequencies.
The native Serial ATA hard disks also require a power supply connector different, part of the standard. The standard power connector similar data, but larger.
A 3.3 V supply is added compared to the PATA, bringing to a total of 15 pins to ensure three if necessary supply voltages : 3.3 V, 5 V and 12 V.
A SATA I, II or III element can be connected to a motherboard SATA I, II or III. The obtained debit will be one of the slowest component. Ex. : a hard drive SATA III on a motherboard SATA II will have a throughput limited by the motherboard to 300 MB/s.
m-SATA or mini-SATA
It is an adaptation of the SATA Protocol intended for netbooks and computer laptops, but also to devices using small HDDs or SSDS. The mini-SATA connector is smaller than the SATA but offers the same performance as the latter. The mini-SATA resembles a mini PCI-Express card, it supports the latest (2013) the 6 Gbps SATA III standard.
e-SATA or external-SATA
It is an adaptation of the SATA Protocol to the connection of external devices. Its main features are :
Voltage show above the standard SATA (500-600 mV instead of 400-600 mV);
Tension of receiving less than the standard SATA (240-600 mV instead of 325-600 mV);
Protocol identical, in order to use the same facilities;
Maximum cable length is greater than the standard SATA (2 m instead of 1 m).
Several manufacturers offer combo plugs where eSATA port sharing, for reasons of space, the taking of a USB2. The USB since USB 3.0 competition seriously eSATA port because it offers rates comparable or even superior to the latter in being more ergonomic as including power supplies 10 lines.
The Micro-SATA interface is available for disks 1.8 \hard, it is especially intended for the ultraportable PCs and tablets. The Micro-SATA connector looks like the standard SATA connector smaller, the power connector is more compact (9 pin instead of 15) and has a keyway located between pins 7 and 8. Theoretical transfer rates of 230 MB/s read and 180 MB/s write.