What is SATA 6. SATA (Interface): Types and speed

#Sata.

Serial ATA (Serial Advanced Technology Attachment)

- A new sequential interface for connecting disk drives, which is replaced by the UltraAta33 / 66/100/133 parallel interface, also known as ATA (IDE) or PATA (Parallel ATA). The serial data interface does not require a stranded plume (7 contacts against 40), so the cable connecting hard drives, SSD or optical drives To the motherboard, much thinner traditional, which contributes to better ventilation inside the case. Another advantage is that the maximum cable length reaches one meter. Increased and bandwidth - at the fastest parallel interface Ultradma 133, it is equal to 133 MB / s, while according to Serial ATA the first version, the data is transmitted at a speed of 150 MB / s. Another advantage of the new interface can be considered the possibility of hot replacement. hard disks or SSD. This possibility for obvious reasons does not apply to hDD With installed operating systemThis is used by the computer - you can connect or disable additional hard drives, and the following rules must be followed: when the storage is added, the loop is first connected, then the power is to be removed, then you must first turn off the power cord, and then the train.

The SATA interface has two data channels, from the controller to the device and from the device to the controller. To transmit the signal, LVDS technology is used, the wires of each pair are shielded vita pairs.

The SATA interface devices use two connector - 7-pin data transmission and 15-pin to provide a power supply. In some hard drives, a 4-pin Molex type connector was used as an alternative power connector. There is also a 13-pin combined connector (7 contacts for data transmission and 6 to power the device) - usually such a connector equipped with HDD and intended for portable devices Type of small-sized laptops or tablets. To connect such drives to the standard SATA connector, you must need a special adapter.

SATA Revision 1.0 (SATA 1.5 Gbit / S)

- The first version of the standard that ensured the actual bandwidth at the level of 1.2 Gb / s (150 MB / s). The actual data transfer rate was approximately 20% lower than the stated 1.5 Gbit / s, for the simple reason that the coding system 8B / 10B was used, i.e. for every 8 bits useful information There are 2 service bits. The main advantage of the SATA interface in front of its predecessor (PATA) is to support the optimization technology of command alternation (), which increases the speed of programs intensively performing random reading operations, especially in multitasking mode.

SATA REVISION 2.0 (SATA 3 GBIT / S)

- The second generation of the interface whose bandwidth increased by approximately two times to 2.4 Gb / s (300 MB / s). The popular names of this interface are SATA II and SATA 2.0. The new audit of the SATA interface has become relevant with the advent of the first SSD drives, the read speed of which exceeded the bandwidth of the SATA / 150 interface.

SATA Revision 3.0 (SATA 6 Gbit / S)

- To date, the last generation of the interface, which, taking into account the same 10B / 8B coding, provides the ability to transmit data at a speed of up to 6 Gb / s (600 MB / s). In addition to the increased interface bandwidth, the drive power management was improved. The final version of the standard was presented on May 27, 2009 and is used to this day. By the way, the SATA-IO consortium does not welcome the interface designations as SATA III, SATA 3.0 or SATA GEN 3 - the official name of the SATA 6GB / S interface. This audit of the interface is completely compatible with previous versions interface, i.e. Any hard drive or SSD with a new interface can easily be connected to a motherboard or controller with SATA / 150 or SATA / 300 interface. There are still some restrictions on working with outdated controllers, which are described in. The last revision of the SATA interface, unlike the previous two revisions, provides sufficient bandwidth for solid-state drives (SSD) created on the basis of the latest and, whose speed for reading and record can exceed the mark of 500 MB / s.

Since 2009, SATA 6GB / S is the newest architecture for hard disks based on plates. "6 Gb / s" refers to the data rate of 6 gigabits per second, which is twice the speed of the previous generation SATA. The International Organization of Serial ATA (SATA-IO), which develops SATA standards, demanded that this SATA third generation is called SATA 6GB / S to avoid adding confusion to the SATA nomenclature, which has already been confused by confusing second generation names.
SATA technology has changed the technology of connection of hard drives, switched from wide uncomfortable parallel cables and ATA data connectors (PATA) to reduce serial cables and connectors. Switching to a full-duplex sequential connection opened the door for faster speeds than the parallel technology could operate, and also opened the inside of the computers' enclosures, which made it possible to increase the air flow, which was vital for faster processors (CPU) and high capacity disks.

The original SATA, also known as SATA 150 or SATA / 150, had a maximum data transfer rate of 1.5 Gb / s or 150 megabytes per second (MB / s). Self quick discs PATA can compete with original SATA, but PATA maximized their impregnable architecture, while SATA just started her work.

The second generation of SATA, often called SATA II, doubled the speed of up to 3 Gb / s or 300 MB / s. Due to the SATA II data transfer rate also called SATA 300, SATA / 300 or SATA 3. You already see confusion with SATA II, which is synonymous with SATA 3.

Now add the third generation SATA, and it is clear why SATA-IO does not want the latest iteration to be called SATA 3, SATA III or even the third generation SATA. By data transfer rate, SATA 6 Gb / s immediately specifies the specification.

According to SATA-IO, the technology is back compatible with previous versions of SATA, and can use the same cables and connectors. Since SATA disks make up almost 100% of the disks used today, the update to SATA 6 Gb / s will be the same as easy as the purchase and installation of a new disk.

SATA 6 Gb / s approached just in time to combine well with USB 3.0, more new USB standard. USB 3.0 supports the maximum theoretical speed of 600 MB / s, ideally suitable for SATA new generation. While USB 3.0 cannot realize your maximum level in the real world, you can not not think that all the time you saved, with external Drivesupporting USB 3.0, and two or more sATA disks 6 Gbps to accelerate saving backups On disk.

While some new technologies are introduced as many new problems as they correct, no one looked back since the introduction of SATA technology. Now with SATA 6 Gb / s and USB 3.0 on the horizon you can argue that everyone looks forward.

Despite the fact that modern HDD has not yet reached the limits of the second version of the SATA standard, for solid-state drives of its capabilities are not enough, and many manufacturers believe that it is time for SATA 3.0.

New round of evolution

To begin with, I clarify the situation with the names: SATA 3.0 is a revision of the technical documentation describing the new generation of the standard, the real devices are characterized as SATA 6 GBIT / S supports the set of functions described in SATA 3.0.

The two main changes in the third interface generation are increased to 6 GB / with bandwidth and extended NCQ capabilities.

The first update will not be in demand even with tight discs of the last generation, because today they do not provide linear reading rates exceeding 150-160 MB / s, however, it is quite relevant for SSD.

The greatest value for traditional drives will have a function is isochronous, i.e. constant data transmission. Heavily loaded HDD, reading and recording information in several streams (rather common in the home PC. The situation in the light of the development of file sharing networks) is often not able to provide a steady read speed for a comfortable viewing of video or listening to audio. SATA 3.0 provides for the activation of a peculiar analogue of QUALITY OF SERVICE network protocols: The application reserves the maximum priority, and the data requested by them is always read primarily and the continuous flow.

Revolutionary such changes, of course, cannot be called, SATA 6 Gbit / S is only a new stage in the evolutionary development of the standard, eliminating some disadvantages of the previous version and revealing the already achieved bandwidth. More interesting practical implementations This interface.

Two approaches to one task

ASUS P7P55D-E Premium

Gigabyte GA-P55A-UD6

Obviously, drives with support for the new SATA standard will first be installed in the latest PCs on Intel and AMD platforms. For the first manufacturer, it is primarily Socket 1156 and the P55 chipset, on the basis of which in the ASUS and Gigabyte rules have already appeared motherboards with support for SATA 6 Gbit / S, equipped with the Marvell 912X series controllers in Gigabyte products, characterized rAID support, and 9123 on ASUS boards.

SATA 6 Gbit / S support demanded from the engineers of both companies of non-trivial technical solutions, and they approached their embodiment in different ways. The reason for this is a feature chipset Intel. P55: Despite the stated compatibility with PCI Express 2.0, the eight lines of this tire provided by the I / O hub, only PCI Express 1.1 correspond to the bandwidth. 250 MB / s are not provided for this lines for a new disk interface, because developers had to go through coating paths.

In ASUS P7P55D-E Premium, data exchange between the controller and the chipset is organized by the simplest engineering point of view: four PCI Express Lines from the IOH logic set lead to the PEX PLX8613 switch, which converts it to two PCI Express 2.0 channels. To it, in turn, the aforementioned Marvell 9123 is connected and uSB controller 3.0 production NEC. Dry figures (4 GB / s for PCI Express 2.0 against 6 GB / s for a new audit SATA) say that this is still not enough, but modern drives are still unlikely to fully load this channel.

Gigabyte GA-P55A-UD6 contains a significantly more sophisticated solution to the problem. It has a special P13PCIE switch, allowing depending on bIOS settings and connected to the device board to use either PCI-E lines provided by the chipset or emitting directly from the processor. If the capabilities of SATA 6 Gbit / S or USB 3.0 are not activated (or disabled manually in BIOS), controllers are satisfied with the speed provided by the chipset. If you need to fully disclose the potential of new standards, the board switches to the use of faster channels (in this case, the graphic connector switches to x8 mode). This solution has also indirect advantages: the path "Controller-processor-RAM" has a smaller latency than the "controller-chip-bus DMI processor-RAM".

Testing

Two hard disks were received in the test laboratory. Seagate Barracuda. Xt capacity of 2 TB supporting SATA 6 Gbit / s. We measured their speed both when connecting to the built-in Intel P55 chipset controller and to Marvell 912X controllers on the ASUS and GIGABYTE boards. In addition, an RAID 0 array on the Gigabyte platform was tested to evaluate whether PCI Express 1.1 is really a deterrent for a two-port controller.

The results are somewhat contradictory and radically diverged for a single HDD and RAID array. From the point of view of synthetic tests, the differences between controllers are minimal and fully explained by the features of their connection. Note that the increase in speed due to the greater data exchange rate with the unique disk buffer we did not find.

Nevertheless, Marvell 912x is simply not able to process as many requests as Intel P55. Judging by the iOMter tests, maximum performance of this core - 125-130 requests per second per channel, while the "native" controller processes 180 requests and is obviously not a deterrent for hard disk. However, this phenomenon is noted only in the FileServer profiles and WebServer utilities of the IOMETER utility, in the remaining cases of HDD "Rent" earlier than the controller.

As for the RAID regime, then the situation is fundamentally different: in terms of linear speed indicators, the array really exceeds the mark of 250 MB / s, which explicitly indicates the justification of the technical tricks applied by Gigabyte. In the connection mode to the chipset, the performance drops by 25% or more. What is especially interesting, at least a built-in Intel P55 controller and is not inferior to Marvell 9128 in synthetic tests, while simulating the operation of real PCs and servers, the latter is ahead of it very significantly. Perhaps it is precisely in this mode that the larger volume and the rate of data exchange with the HDD buffer contributes its contribution.

Test results suggest that today the implementation of SATA 6 Gbit / S is justified only for high-loaded RAID arrays and, possibly, SSD drives, and for one-piece configurations there are no advantages of the new generation of the interface. Availability of relevant controllers on the newest motherboards - Rather, the imaging than really necessary step. Nevertheless, the indicators even two-way RAID arrays confirm that the moment when SATA 3 Gbit / s becomes obsolete not only morally, is already very close.

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On the this moment The most common interface is. SATA Although you can find on sale, but the interface is already considered obsolete, moreover, they have already begun to do.

It is not necessary to be confused with SATA 3.0 Gbit / s, in the second case we are talking about the SATA 2 interface, which has a bandwidth equal to 3.0 Gbps (SATA 3 bandwidth is equal to 6 Gbps)

Interface - A device transmitting and converting signals from one component of the equipment to another.

Types of interface. PATA, SATA, SATA 2, SATA 3, and TD.

Different generation drives used interfaces: IDE (ATA), USB, Serial ATA (SATA), SATA 2, SATA 3, SCSI, SAS, CF, EIDE, Firewire, SDIO and Fiber Channel.

IDE (Attachment Advanced Technology ADVANCED TECHNOLOGY ATTACHMENT)- the parallel interface for connecting drives, which is why it was changed (with output SATA.) on the PATA (Parallel ATA). Previously used to connect hard drives, but was ousted by the SATA interface. Currently used to connect optical drives.

SATA (Serial ATA) - Serial interface for exchanging data with drives. A 8-PIN connector is used to connect. As in the case of PATA - It is obsolete, and is used only to work with optical drives. The SATA (SATA150) standard provided throughput equal to 150 MB / s (1.2 Gbit / s).

SATA 2 (SATA300). Standard SATA 2 increased bandwidth in two, up to 300 MB / s (2.4 Gb / s), and allows you to work at a frequency of 3 GHz. Standards SATA and SATA 2 are compatible with each other, however, for some models, you must manually install modes, rearrange the jumpers.

Although about the requirement of specifications correctly call SATA 6GB / S. This standard in two increased data transfer rate to 6 Gb / s (600 MB / s). Also, positive innovations include the NCQ software control function and commands for continuous data transmission for a high priority process.

Although the interface was presented in 2009, he does not use much popular with the manufacturers and does not meet in stores not so often. In addition to hard drives, this standard is used in SSD (solid-state discs).

It is worth noting that in practice the bandwidth of SATA interfaces are not distinguished by the data rate. Almost the speed of recording and reading disks does not exceed 100 MB / s. An increase in indicators is only affected by the bandwidth between the controller and the drive.

SCSI (Small Computer System Interface) - The standard is applied in servers where the data is needed.
SAS (Serial Attached SCSI) - Generation that has come to change the SCSI standard that uses serial data transmission. Like SCSI is used in workstations. Fully together with Interface SATA.
CF (Compact Flash) - Interface for connecting memory cards, as well as for 1.0 inch hard drives. Two standards are distinguished: Compact Flash Type I and Compact Flash Type II, the difference in thickness.

Firewire. - Alternate interface of slower USB 2.0. Used to connect portable. Supports speed up to 400 MB / s, however, the physical speed is lower than that of the usual. When reading and writing, the maximum port is 40 MB / s.

Despite the fact that modern HDD has not yet reached the limits of the second version of the SATA standard, for solid-state drives of its capabilities are not enough, and many manufacturers believe that it is time for SATA 3.0.

New round of evolution

To begin with, we clarify the situation with the names of standards and interfaces. A common abbreviation SATA II (or SATA-2) is not really true and is simply established. In fact, the term SATA 2.0 is used for the standard, meaning the second revision of the documentation, which contains all information about it. For devices, (optical drives, hard drives, SSD, controllers, etc.), the set of technologies and its compliance described in the standard are important. If it fully satisfies the description, the device is characterized as supportive SATA 3 Gbit / S - this is how marketing purposes are called their physical embodiment.

Similar to the situation and with a new audit: Technical documentation describes the third generation of Standard - SATA 3.0, adopted on May 27, 2009, and real devices are considered supporting SATA 6 Gbit / S characteristics.

SATA 3.0 contains the following innovations:

• interface bandwidth increased to 6 GB / s;
• for NCQ introduced new team For isochronous data transfer mode, the possibility of NCQ software control is introduced;
• enhanced device management capabilities;
• there are new forms of connectors for 1.8-inch HDD and thin optical laptop drives

The first update will not be in demand even with tight discs of the last generation, since today they do not provide linear reading rates exceeding 150-160 MB / s. However, in the future, the SATA 3 Gbit / S threshold will probably be passed and they will also receive dividends from this innovation. solid-state drivesSince they have long been "overlapped" in the limit of the last revision of the interface. For the HDD, the only manifestation of the increased bandwidth of the tire will be the increased data exchange rate between the controller and the disc buffer, which the manufacturers did not fail, expanding its volume to 64 MB.

The greatest value for traditional drives will have a function is isochronous, i.e. constant data transmission. Heavy loaded HDD, which you have to read and record information in several streams (quite common in the home PC. The situation in the light of the development of file sharing networks) is often not capable of providing a steady read speed for a comfortable viewing of video or listening to audio, at least the amount of data readable and is small. SATA 3.0 provides for the possibility of activating a peculiar analogue of Quality of Service in network protocols: the application is redundant maximum priority, and the data requested by it is always read primarily and continuously. Most likely, it will greatly affect performance background processes, however, for the user most often more important than the so-called User Experience - the speed in the tasks that it determines as the main, and in this case new feature It will be more good.

Revolutionary such changes, of course, cannot be called, SATA 6 Gbit / S is only a new stage in the evolutionary development of the standard, eliminating some disadvantages of the previous version and revealing the already achieved bandwidth. The practical implementation of this interface is more interesting.

Two approaches to one task: ASUS P7P55D-E Premium and Gigabyte GA-P55A-UD6

ASUS P7P55D-E Premium

Gigabyte GA-P55A-UD6

Obviously, drives with support for the new SATA standard will first be installed in the latest PCs on Intel and AMD platforms. For the first manufacturer, it is primarily Socket 1156 and the P55 chipset, on the basis of which in the ASUS and Gigabyte rules have already appeared motherboards with SATA 6 GBIT / S support, equipped with the Marvell 912x - 9128 series controllers in Gigabyte products, characterized by RAID support, and 9123 on Asus boards. For AMD Socket AM3 Gigabyte also already prepared three models with support for the new standard, other vendors will surely wait to wait.

SATA 6 Gbit / S support demanded from the engineers of both companies of non-trivial technical solutions, and they approached their embodiment in different ways. The reason for this is the feature of the Intel P55 chipset: despite the stated compatibility with PCI Express 2.0, the eight lines of this tire provided by an I / O hub, only PCI Express 1.1 correspond to bandwidth. With these lines of 250 MB / s are not enough for a new disk interface (in the end, what's the point to put a quick controller and limit its tire to which it is connected?), Because developers had to go by coarse tracks.

In ASUS P7P55D-E, the exchange of data between the controller and the chipset is organized the most simple engineering point of view: four Lines of PCI Express from IOH Logic Sets to the PEX PLX8613 switch, which converts it to two PCI Express 2.0 channels throughput 500 MB / s. To it, in turn, the aforementioned Marvell 9123 and the USB 3.0 controller manufactured by NEC are connected. Dry figures (4 GB / s for PCI Express 2.0 against 6 GB / s for a new audit SATA) say that this is still not enough, but modern drives are still unlikely to fully load this channel.

Gigabyte GA-P55A-UD6 contains a significantly more sophisticated solution to the problem. Instead of a simple PCI Express bridge, it has a special P13PCIE switch, which allows you to use either the PCI-E lines connected to the BIOS cards, which are directly from the chipset, or exit directly from the processor (Recall that Core i7 and i5 on the LynnField core, Equally, as well as ready to exit the model with the Clarkdale kernel, equipped with a PCI Express 2.0 x16 controller directly on the crystal). If the capabilities of SATA 6 Gbit / S or USB 3.0 are not activated (or disabled manually in BIOS), controllers are satisfied with the speed provided by the chipset. If you need to fully disclose the potential of new standards, the board switches to the use of faster channels (in this case, the graphic connector switches to x8 mode). This mode has also indirect advantages: the "controller-processor-operational memory" path has a smaller latency than the "controller-chipset-bus DMI processor-RAM".

Testing

The test laboratory received two SEAGATE BARRACUDA XT hard disk with a capacity of 2 TB supporting SATA 6 Gbit / S. We measured their speed both when connecting to the built-in Intel P55 chipset controller and to Marvell 912X controllers on the ASUS and GIGABYTE boards. In addition, an RAID 0 array on the Gigabyte platform was tested to evaluate whether PCI Express 1.1 is really a deterrent for a two-port controller.

The results are somewhat contradictory and radically diverged for a single HDD and RAID array. From the point of view of synthetic tests (response time and maximum linear reading and recording speed) differences between controllers are minimal and fully explained by the features of their connection. Note that the increase in speed due to the greater data exchange rate with the unique disk buffer we did not find.

However, Marvell 912X is simply not able to process as many requests as Intel P55. Judging by the iOMter tests, the maximum performance of this kernel is 125-130 requests per second per channel, while the "native" controller processes 180 requests and is obviously not a deterrent for a hard disk. However, this phenomenon is noted only in the FileServer profiles and WebServer utilities of the IOMETER utility, in the remaining cases of HDD "Rent" earlier than the controller.

As for the RAID regime, then the situation is fundamentally different: in terms of linear speed indicators, the array really exceeds the mark of 250 MB / s, which explicitly indicates the justification of the technical tricks applied by Gigabyte. In the plug connection to the chipset, the performance drops by 25% or more, while the controller driver also adds speed due to the caching of requests in random access memory (No other latency of 3.3 ms is impossible to explain when writing). What is most interesting, at least a built-in Intel P55 controller and is not inferior to Marvell 9128 according to synthetic tests, while simulating the operation of real PCs and servers, the latter is ahead of it very substantially (with charts can be found on the site). Perhaps it is precisely in this mode that the larger volume and the rate of data exchange with the HDD buffer contributes its contribution.

The results of testing suggest that today the implementation of SATA 6 Gbit / S is justified for high-loaded RAID arrays and, possibly, SSD drives, and for one-piece configurations there are no advantages of the new generation interface. The presence of appropriate controllers on the latest motherboards is rather an imaging than really necessary step. Nevertheless, the indicators even two-digish RAID arrays confirm that the moment when SATA 3 Gbit / s becomes obsolete not only morally, is already very close.