SATA: Serial Advanced Technology Attachment

Computers are made up of a number of technologies that work together. Processors, memories, graphics chips and other devices evolve and enhance the user experience. With items such as hard drives, DVD or Blu-ray players and SSD drives could not be different. According to ABBREVIATIONFINDER, SATA stands for The Serial Advanced Technology Attachment.

In this text you will learn more about this technology, such as its differentials compared to the Parallel ATA (or IDE) standard, the basic differences of its versions, as well as its main features and advantages.

SATA x IDE (PATA)

The SATA (Serial ATA) standard is a technology for hard disks, optical drives and other data storage devices that came on the market in the year 2000 to replace the traditional PATA interface (Parallel ATA , ATA only , or IDE).

The name of both technologies already indicates the main difference between them: the PATA makes transfer of data in parallel, that is, it transmits several bits at a time, as if they were side by side. In SATA, the transmission occurs in series, as if each bit were one after the other.

Because of this, you can imagine PATA is faster, right? Actually, it’s not. Parallel data transmission (usually 16 bits at a time) causes a problem known as “noise”, which is nothing more than loss of data caused by interference. To address the problem, manufacturers have implemented mechanisms in PATA HDs to reduce noise. One is the recommendation to use flat cables (the cable connecting the HD to the motherboard) with 80 lanes (that is, with eighty wires) instead of the traditional 40-way cables. The other ways act as a kind of shield against interference.

In the case of the SATA standard, the noise practically does not exist, even though its cable of connection to the computer usually has only 4 ways and is also armored. This ends up bringing another advantage to the SATA, because as the cable has reduced dimensions, the internal space of the computer is better utilized, facilitating even the circulation of air. The cable can also be larger, can work without problems having 1 meter, for example.

In addition, SATA technology works with higher clock rates compared to PATA. Higher frequencies result in more data being transmitted at a time, but more room for noise (interference). However, serial transfer serves as protection against this problem.

The Parallel ATA standard has its data transmission speed limited because of noise. The latest specification of this technology is the ATA 133 that allows, at most, a transfer rate of 133 MB per second. Serial ATA, for its part, can use much higher speeds.

There is another interesting feature in the SATA standard: HDs using this interface do not need jumpers to identify the master (primary) or slave (secondary) disk . This is because each device uses a single transmission channel (PATA allows up to two devices per channel), linking its full capacity to a single HD.

In order to avoid incompatibility with Parallel ATA devices, it is possible to install type HDDs on SATA interfaces through adapter cards. In addition, many manufacturers have released motherboard models with both interfaces. This occurred mainly during the transition period from one technology to another. Today, it is quite difficult to find new devices with PATA interface.

Another interesting feature of SATA is the possibility of using the hot-swap technique , which makes it possible to exchange a Serial ATA device with the connected computer. For example, it is possible to swap an HD without having to disconnect the machine for this. This feature is very useful on servers that need maintenance / repairs, but they can not stop working.

It is also worth mentioning that it is possible to find equipment of the type multiplier port that allow the connection of more than one device in a single port SATA, similar to what happens with the USB hubs.

SATA Interface Versions

As with other technologies, the SATA standard is improved over time, resulting in new versions. The following is a brief description of the existing versions until the closing of this text.

SATA I

The first version of SATA works with a maximum data transfer rate of 150 MB per second (MB / s). This version also receives the following names: SATA 150 , SATA 1.0 , SATA 1.5 Gb / s (1.5 gigabits per second) or, as you know, just SATA I .

Theoretically, this version of SATA can work with transfer rates of up to 1.5 Gb / s, resulting in a maximum range of 192 MB / s (megabytes per second). However, the interface uses an 8B / 10Bname encoding scheme that limits this speed to 1.2 Gb / s, something around 150 MB.

The 8B / 10B encoding has this name because each 8-bit set is handled in a 10-bit packet. The two additional bits are used for synchronization purposes, making data transmission more secure and less complex.

The SATA I frequency is 1.5 GHz.

SATA II

It did not take long for a version called SATA II ( SATA 3 Gb / s , SATA 2.0 or SATA 300 ) to emerge , the main characteristic of which is the data transmission speed of up to 300 MB / s, twice SATA I, higher by also using 8B / 10B encoding. This substantial gain of speed is mainly due to the clock of this version, of 3 GHz.

Interestingly, many hard drives that use this specification can rely on a jumper that limits the device’s speed to 150 MB / s, a measure applied to make these hard drives work on SATA I-only motherboards.

Here is a note: the entity that controls the SATA standard (made up of a group of manufacturers and related companies) is currently called SATA-IO ( SATA International Organization ). The problem is that the previous name of this organization was SATA-II, which generated some confusion with the second version of the technology.

Taking advantage of this situation, many manufacturers inserted SATA-II seals into their SATA 1.0 hard drives in an apparent attempt to confuse the less attentive users, making them think that these drives were actually the second generation of SATA HDDs. Therefore it is necessary to look carefully at the technical specifications of the hard drive at the time of purchase.

Fortunately, few HD models fit in this context. Anyway, this situation evidences the fact that the denominations SATA I, SATA II and, later, SATA III, were never officially adopted, although its use in the market is common.

SATA III

2009 was the launch year for the final set of specifications for the third version of Serial ATA technology, called SATA III ( SATA 6 Gb / s , SATA 3.0 or SATA 600 ). This standard theoretically allows transfer rates of up to 600 MB per second.

SATA III also uses an enhanced version of the NCQ technology (discussed in the next topic), has better power management, and is compatible with 1.8-inch connectors specific to small-sized devices. The SATA III standard is especially interesting for use on SSD drives , which use flash memory to achieve higher throughputs than hard drives.

The SATA III specification works with up to 6 GHz frequency, also making use of 8B / 10B encoding.

It is worth noting that in terms of speed aspect, the mentioned values ​​(150 MB, 300 MB and 600 MB) are hardly achieved. These rates indicate the maximum data transmission capacity between the hard drive and the computer, but are hardly used in their entirety, as this depends on a combination of factors such as memory content, processing, other hard drive technologies, etc. .

Technologies related to SATA

Manufacturers can add technologies to their products to differentiate them in the market or to meet a particular demand, which means that certain features may not necessarily be mandatory on a hard drive just because it is SATA. Let’s look at some of them:

– NCQ (Native Command Queuing): NCQ is mandatory for SATA II and SATA III, but was optional in the SATA I standard. It is a technology that allows HD to organize the requests for recording or reading data in an order that causes the heads to move as little as possible, increasing (at least theoretically) the performance of the device and its useful life. Understand the operation of the NCQ here better ;

– Link Power Management: This feature allows the HD to use less electricity. For this, the hard drive can take three states: active ( active ), partially active ( partial ) or inactive ( slumber ). Thus, the HD receives power according to its current use;

– Staggered Spin-Up: This is a very useful feature in RAID systems , for example, it allows you to enable or disable HDs working together without interfering with the operation of the disk group. In addition, Staggered Spin-Up technology also improves the power distribution between disks;

– Hot Plug: In essence, this feature allows you to connect the disk to the computer with the operating system in operation. This is a feature commonly used on removable-type HDDs.

SATA connectors and cables

The connectors and cables used in SATA technology offer two major advantages to the user: they take up less space inside the computer; and have easier and safer docking (it’s virtually impossible to connect a SATA cable in an inverted way). The same goes for the power connector of the HD (or other compatible device).

The SATA connector consists of seven tracks:

  1. Ground
  2. A + (sending data)
  3. A- (sending data)
  4. Ground
  5. B + (data reception)
  6. B- (data reception)
  7. Ground

Channels A and B serve the data traffic itself. The channels with negative symbol (A- and B-) are “inverted replicates” used as protection against interference: on receiving the data, the + and – signals are compared and, from the differences, it is possible to identify “noises” in the streaming. The other pins are for grounding.

Note that because there are ways to send and receive data, the transmission in a SATA connection occurs in both directions, that is, it is a full-duplex technology , where you can receive and send information at the same time.

mSATA

You may see the name mSATA ( mini-SATA ) somewhere. This is not necessarily a new SATA specification, but rather a connection pattern especially designed for small-size SSDs that can be used, for example, in ultrabooks (notebooks with small thicknesses) or even tablets.

In this case, the SSD drive is usually provided in the form of a card, having dimensions similar to that of a credit card. The idea here is to alleviate the problem of the fragmentation of connector formats, since each manufacturer adopted a different standard.

eSATA

Coming from the term external SATAeSATA is a type of port that allows the connection of external devices to a SATA interface of the computer. This feature is particularly interesting for users who want to take advantage of the compatibility of external hard drives with SATA technology for higher data transfer rates.

Many manufacturers offer motherboards and notebooks that have a port that works as both eSATA and USB , and, of course, a port that is just eSATA. For cases where there is no such port, you can use adapters that are installed in PCI Express slots , for example.

ESATA offers the advantage of enabling the speed of the SATA version in use, on the other hand, it does not provide electrical power, which means that only devices with an external power supply can use it.

One of the solutions found by the industry to overcome this limitation is eSATAp, which is nothing more than a scheme that uses an eSATA-compatible USB port in conjunction with two power pins, usually 12V. If pins are required 5 V, you can use what is already provided by the USB port.

Finishing

The Serial ATA standard began to be officially developed in the year 1997 and emerged from an initiative of Intel with approximately 70 companies. The idea was formed by the prediction that future data storage technologies would require hitherto unsupported transfer rates. SATA technology proved to be a solution to this issue without, however, having higher production costs as a consequence, one of the factors that were decisive for its wide acceptance in the market.