What is SATA 6Gb/s?

SATA is the abbreviation of Serial ATA, namely Serial ATA. It is a computer bus whose main function is to transfer data between the motherboard and a large number of storage devices such as hard disks and optical drives. This is a new type of hard disk interface that is completely different from serial PATA, which is named because it uses serial transmission of data. The SATA bus uses an embedded clock signal and has stronger error correction capabilities. Compared with the past, the biggest difference is that it can check the transmission instructions (not just data). If errors are found, they will be corrected automatically. Improved the reliability of data transmission to a certain extent. The serial interface also has the advantages of simple structure and hot plug support.

Foreword

The emergence of the SATA standard has caused a big wave in the computer storage industry. In addition to changing the past parallel transmission method to a serial method, not only has the effective reduction in the size of the cable, but also the transmission speed Considerable improvement.

Changes to the SATA standard

In fact, the common name of SATA II is the name of a committee. The purpose of the committee was to establish the earliest SATA 1.x standard. The organization was later renamed SATA International (SATA-IO). But the name of SATA II has remained. As related products introduced by different manufacturers have different functions or support levels, the naming rules of each SATA product are different.

Because SATA-IO does not mandate the naming rules and functional requirements, it also caused a lot of product positioning difficulties in the early stages of promotion. In terms of naming, most manufacturers usually use specific functions as the naming rule. Most of them are usually based on their maximum transmission speed. Common names such as SATA 300, SATA 3Gb / s, and SATA 3G are used. Some also directly use SATA II Supports the name of the specifications. Later products have quite complete hardware specifications, so most of them abandoned the past speed naming rules. In addition, SATA-IO will be identified by various manufacturers in the autumn IDF exhibition at the end of August 2005. SATA II content: such as 3Gbps, local command queue (NCQ), port multipliers, and port selectors, are unified into the standard specification of SATA 2.5, which greatly reduces market disruption. In the first quarter of 2007, SATA-IO introduced the version 2.6 specification, and a further version 3.0 specification will be launched in the second half of the year.

The advantages of SATA still have to face the reality

The emergence of SATA 1.0 represents the computer industry's formal transition from low-clock side-by-side transmission to high-clock sequence transmission. The initial specification is set at 1.5Gbps, which obviously has more abundant transmission energy than the IDE interface in the past. However, although SATA provides such a wide bus, the speed of hard disk drives is very slow, and the increase in speed and disk density is not fast enough, so the increase in SATA bus speed is not significant.

SATA has become a universal storage interface standard

An example that many people like to cite: riding a 50CC lamb motorcycle on a 200-speed highway, which is enough to fully describe the embarrassment faced by hard disk drives. According to the SATA 1.0 specification, its maximum transmission speed is about 150Mbyte / s, and even a high-end SATA hard disk with a speed of more than 10,000 rpm, the continuous transmission speed cannot exceed 100MByte / s. I want to make use of the high bus bandwidth of SATA. , You must use a disk array to have a solution, and another method that can take advantage of the high bandwidth of the SATA interface is to use a hard disk external device with a port sharer to divide the bandwidth of a single SATA port evenly to different numbers. Hard disk use, as far as a single hard disk is concerned, the transfer speed will not have a greater advantage than in the IDE interface.

The difference between eSATA connector and SATA connector

ESATA and SATA interface

Secondly, although SATA has a standard for hot plugging, most of the connecting cables are designed for internal hard disks. The maximum number of plugging and unplugging is only about 200 times. If the number of plugging and unplugging is exceeded, the cable connector will be deteriorated. It may cause damage to the hard disk. Even for eSTAT cables for external applications, the number of insertions and removals is still only about 2,500 times, which is far from the USB interface. However, this aspect involves the connection between the cable material and the cost. Although, in theory, a higher number of plugs can be reached, but whether the price is acceptable to consumers is also key. Although the SATA cable has the advantage in width, the length is limited to less than 2 meters, which is a considerable limitation for some applications, but this can be solved by xSATA.

Enhancements to the SATA version 2.6 specification

The technologies added in SATA version 2.6 are mainly for small embedded storage or mobile applications. These technologies include the following:

1. The SATA optical drive can be installed in the built-in daughter card cables and connectors in small devices (such as small form factor).

2. A 1.8-inch hard disk can be mounted to a mini SATA connector such as a UMPC.

3. Now that the micro-connector specifications are available, it is naturally necessary to design built-in or external multi-channel cables and connectors for such micro-connectors.

4. NCQ priority enhancement allows data to be dynamically assigned priority levels for transmission of data in complex loading environments to avoid traffic jams.

5. Allow notebook computer to shut down or not use NCQ function, in order to avoid the situation that the driver is incomplete, it will slow down the system performance.

Below: Miniaturized connection interface made by SATA 2.6. (SATA-IO)

SATA version 2.6 enhanced for mobile applications

From the above strengthening points, we can see that SATA version 2.6 is mainly aimed at smaller applications, such as samll form factor or internal and external specifications such as UMPC. However, the number of storage devices in such applications is limited. And the speed of the storage device itself will be affected by different factors such as the rotational speed (for example, the 1.8-inch hard disk commonly used in UMPC has a maximum transmission speed of about 20MByte / s, which is less than one-third of the traditional 3.5-inch hard disk.) In the SATA specification It seems that the import is not so necessary. UMPC itself is not capable of supporting disk arrays. The only application that can use the power of SATA is to use a port sharer to connect multiple external storage devices.

The disadvantages of traditional mechanical hard drives are clearly visible on the UMPC. Not only is the power consumption large, the speed is slow, and the capacity growth rate is not fast. Therefore, the sudden rise of solid-state disks (SSDs) may become a boost in the promotion of SATA bandwidth. However, from another perspective, the UMPC may also have a built-in Express Card interface. Compared with SATA, the expansion of Express Cards in terms of specifications, speed performance, and connection methods is actually more advantageous than SATA. In the next two to three years, the price and capacity of SSDs will still be unacceptable to the average consumer, and traditional micro hard disks still have their living space. Therefore, the competition between SATA and Express Cards in this regard is still uncertain.

The next stage of SATA 3.0

The biggest improvement of SATA 3.0 is to increase the maximum transmission bandwidth of the bus to 6Gbps. This greatly increases the application space of port sharers and connectors. In external applications with high-capacity and high-speed transmission requirements Can play its strengths. The connection test with better endurance is also in progress, but so far, its details are not clear, but with its large bandwidth, it is actually beyond the scope of general consumer applications and focuses on The market for specific professional applications is also much smaller.

Mechanical hard disks will continue to exist for a long time to come, and the increase in transmission speed will also maintain the current rate. Therefore, hardware manufacturers are bound to develop more different connection methods in order to effectively consume these huge The bandwidth allows consumers to more directly feel the benefits of increased numbers, instead of focusing only on the promotion of written specifications, which cannot bring users the benefits of related applications.