Serial ATA or SATA is simply the hard disk standard created to replace the parallel ATA interface, aka IDE. The theoretical maximum throughput of Serial ATA is a disk of 150 MB / s or 300 Mb / s, compared to 133 MB / s of an IDE hard drive. We will explain everything you need to know about Serial ATA.
The traditional IDE port (now called "Parallel ATA", or simply parallel IDE PATA) transfers data in parallel. The advantage of parallel transmission is that it is faster than serial transmission, it transmits several bits at a time. Its major disadvantage, however, is in relation to noise. How many wires have to be (at least one for each bit to be transmitted at a time), a wire generates interference in another. It is for this reason that the hard drives ATA-66 and above need a special cable, 80-way.The difference between this 80-wire cable and IDE cable common to 40 lanes is that it has a ground wire between each original wire, which acts as a shield against interference. In our tutorial Everything You Need to Know About ATA-66 hard drives, ATA-100 ATA-133 and an in-depth this issue. Currently the maximum transfer rate we have in the IDE standard is 133 MB / s (ATA-133).
Serial ATA, on the other hand, the transmission of data is in serial mode, ie, transmitting one bit at a time. Most people think that serial transmission is slower than parallel transmission. It turns out that this is only true if we compare the two types of transmissions using the same clock rate. In this case the parallel transmission will be at least eight times faster, since at least eight bits (one byte) will be transmitted per clock cycle, while in only one serial transmission bit is transmitted per clock cycle. However, if a higher clock rate is used in serial transmission, it can be faster than parallel transmission. This is exactly what happens with Serial ATA.
The problem in increasing the throughput of parallel transmission is having to increase the clock, since the higher the clock are the biggest problems related to electromagnetic interference. Since serial transmission uses only one wire to transmit data, it has fewer problems with noise which allows for high clock rates, resulting in a higher transfer rate.
The throughput of the Serial ATA standard is 1,500 Mbps. As this pattern uses the 8B/10B encoding scheme (the same encoding scheme used in Fast Ethernet networks) - where each group of eight bits is coded into a signal of 10 bits - its effective throughput is 150 MB / s. Serial ATA devices working at this speed are also known as SATA-150. Serial ATA II provides new features as technology Native Command Queuing (NCQ), plus a transfer rate of 300 MB / s, double the original SATA standard. Devices that can run at this speed are also known as SATA-300. The next standard to be released will be SATA-600.
It is important to note that the SATA II and SATA-300 are not synonymous. You can build a device that runs only at 150 MB / s but using at least one of the new features offered by SATA II, and NCQ. This would be a SATA II device, although not run at 300 MB / s.
The Native Command Queuing (NCQ) increases hard disk performance by reordering the commands send by the computer. In summary, if your motherboard has SATA II with NCQ support, buy a hard drive that also has support for this technology.
It is also important to note that Serial ATA implements two separate data paths, one for transmitting and one for receiving data. On parallel only one path is used, which is shared for both data transmission and reception. Serial ATA cable consists of two pairs of wires (one for transmission and another for receiving) using differential transmission. In addition to the wireless transmission and reception, three ground wires are used. Serial ATA cable uses therefore seven wires.
Another advantage of using serial transmission is that fewer wires are needed in the cable. Parallel IDE ports use a 40-pin connector and one 80-wire cable. The Serial ATA uses a seven-pin connector and a cable with seven wires. This helps a lot in the airflow inside the PC, since thinner cables do not obstruct the air passage.
In the following figures you can compare Serial ATA to IDE Parallel: Serial ATA cable as it looks, its size compared to the IDE cable 80-way and the physical aspect of the Serial ATA port for IDE port.
Installation
Installing Serial ATA differs somewhat from the conventional installation of IDE devices, since the Serial ATA is a point-to-peer, meaning you can connect only one device per port (IDE ports allow the installation of two per port using the master / slave configuration). Therefore, installing a Serial ATA device is easier than installing an IDE device: connect one end of the Serial ATA port (usually located on the motherboard) and plug the other end of the device you want to connect ( a hard disk, for example). Since this connector has a notch, the facility can not be done the wrong way.
The Serial ATA standard also defines a new type of power connector of 15 pins. This became the standard connector from the ATX specification 1.3. So if your PC has an ATX power supply 1.3 or higher, it will have this connector. Despite a 15-pin connector is used, this connection uses only five wires (a +12 V, a +5 V, +3.3 V and one of two ground wires).
Some Serial ATA drives still use the old power connector 4-pin, which should be used if you are installing your hard drive into a PC with an inferior power supply to ATX specification 1.3. You should only use this connector if your power supply does not have Serial ATA power cable.
Hard Drives SATA-300 may have a jumper setting to force it to work like a SATA-150. The problem is that this jumper is installed in the SATA-150, limiting the performance of the disk if it is installed on a motherboard with SATA-300 ports. The correct setting of this jumper is very important and will describe in detail in the next page.
Installing a SATA hard disk is therefore very simple: remove or change the jumper SATA-150/300 (if your disk has this jumper, will talk about setting this jumper on the next page), connect the cable Serial ATA data and power cable with your computer turned off. This is all you need to do.
Jumper SATA-150/SATA-300
As some hard drives SATA-300 do not work properly on motherboards with SATA-150 ports, some have a jumper SATA-150/SATA-300 (also known as jumper 1.5 Gbps / 3 Gbps). The problem is that by default this jumper is set to position "SATA-150", thus limiting the performance of hard disk if it is installed on a motherboard with SATA-300 ports. We will show you the performance impact caused by wrong configuration of a SATA-300 below.
So before installing a SATA-300 hard drive you should check if it has a jumper SATA-150/SATA-300 and if this jumper is set in the correct position: If you have an old motherboard with SATA-150 you should maintain this position jumper on SATA-150, but if your motherboard has SATA-300 - as with almost all motherboards on the market today - you should move it to position "SATA-300". This information can usually be found on the label of the hard disk.
This particular hard drive (a Seagate Barracuda 7200.10 160 GB) comes with a jumper limiting the performance of the disk at 150 MB / s (1.5 Gbps), see Figure 9. To make it work properly as a SATA-300 device must remove this jumper (see diagram in Figure 8). In this case the jumper can be removed with a small screwdriver, small pliers or tweezers. Note that depending on the model of hard drive you can move the position of this jumper instead of removing it. So it is very important that you pay attention to what is written on the label of your hard drive.
What is the performance impact of a hard disk SATA-300 configured incorrectly? We did some tests to verify this. We measured the throughput of our Seagate Barracuda 7200.10 160 GB with three programs different: SpeedDisk32, HD Tach and HD Tune. We started the test with the jumper in its default configuration (SATA-150 ") and then removed it, which meant that the disk device actually works as a SATA-300.
As you can see the results in all three programs show the same thing. Although the transfer rates of maximum and minimum average remained the same, with the jumper in position-300 SATA transfer rate of pressure increased from 60% to 69%.
In short, do not forget to verify the existence and correct configuration of this jumper when installing hard drives SATA-300!
The traditional IDE port (now called "Parallel ATA", or simply parallel IDE PATA) transfers data in parallel. The advantage of parallel transmission is that it is faster than serial transmission, it transmits several bits at a time. Its major disadvantage, however, is in relation to noise. How many wires have to be (at least one for each bit to be transmitted at a time), a wire generates interference in another. It is for this reason that the hard drives ATA-66 and above need a special cable, 80-way.The difference between this 80-wire cable and IDE cable common to 40 lanes is that it has a ground wire between each original wire, which acts as a shield against interference. In our tutorial Everything You Need to Know About ATA-66 hard drives, ATA-100 ATA-133 and an in-depth this issue. Currently the maximum transfer rate we have in the IDE standard is 133 MB / s (ATA-133).
Serial ATA, on the other hand, the transmission of data is in serial mode, ie, transmitting one bit at a time. Most people think that serial transmission is slower than parallel transmission. It turns out that this is only true if we compare the two types of transmissions using the same clock rate. In this case the parallel transmission will be at least eight times faster, since at least eight bits (one byte) will be transmitted per clock cycle, while in only one serial transmission bit is transmitted per clock cycle. However, if a higher clock rate is used in serial transmission, it can be faster than parallel transmission. This is exactly what happens with Serial ATA.
The problem in increasing the throughput of parallel transmission is having to increase the clock, since the higher the clock are the biggest problems related to electromagnetic interference. Since serial transmission uses only one wire to transmit data, it has fewer problems with noise which allows for high clock rates, resulting in a higher transfer rate.
The throughput of the Serial ATA standard is 1,500 Mbps. As this pattern uses the 8B/10B encoding scheme (the same encoding scheme used in Fast Ethernet networks) - where each group of eight bits is coded into a signal of 10 bits - its effective throughput is 150 MB / s. Serial ATA devices working at this speed are also known as SATA-150. Serial ATA II provides new features as technology Native Command Queuing (NCQ), plus a transfer rate of 300 MB / s, double the original SATA standard. Devices that can run at this speed are also known as SATA-300. The next standard to be released will be SATA-600.
It is important to note that the SATA II and SATA-300 are not synonymous. You can build a device that runs only at 150 MB / s but using at least one of the new features offered by SATA II, and NCQ. This would be a SATA II device, although not run at 300 MB / s.
The Native Command Queuing (NCQ) increases hard disk performance by reordering the commands send by the computer. In summary, if your motherboard has SATA II with NCQ support, buy a hard drive that also has support for this technology.
It is also important to note that Serial ATA implements two separate data paths, one for transmitting and one for receiving data. On parallel only one path is used, which is shared for both data transmission and reception. Serial ATA cable consists of two pairs of wires (one for transmission and another for receiving) using differential transmission. In addition to the wireless transmission and reception, three ground wires are used. Serial ATA cable uses therefore seven wires.
Another advantage of using serial transmission is that fewer wires are needed in the cable. Parallel IDE ports use a 40-pin connector and one 80-wire cable. The Serial ATA uses a seven-pin connector and a cable with seven wires. This helps a lot in the airflow inside the PC, since thinner cables do not obstruct the air passage.
In the following figures you can compare Serial ATA to IDE Parallel: Serial ATA cable as it looks, its size compared to the IDE cable 80-way and the physical aspect of the Serial ATA port for IDE port.
Installation
Installing Serial ATA differs somewhat from the conventional installation of IDE devices, since the Serial ATA is a point-to-peer, meaning you can connect only one device per port (IDE ports allow the installation of two per port using the master / slave configuration). Therefore, installing a Serial ATA device is easier than installing an IDE device: connect one end of the Serial ATA port (usually located on the motherboard) and plug the other end of the device you want to connect ( a hard disk, for example). Since this connector has a notch, the facility can not be done the wrong way.
The Serial ATA standard also defines a new type of power connector of 15 pins. This became the standard connector from the ATX specification 1.3. So if your PC has an ATX power supply 1.3 or higher, it will have this connector. Despite a 15-pin connector is used, this connection uses only five wires (a +12 V, a +5 V, +3.3 V and one of two ground wires).
Some Serial ATA drives still use the old power connector 4-pin, which should be used if you are installing your hard drive into a PC with an inferior power supply to ATX specification 1.3. You should only use this connector if your power supply does not have Serial ATA power cable.
Hard Drives SATA-300 may have a jumper setting to force it to work like a SATA-150. The problem is that this jumper is installed in the SATA-150, limiting the performance of the disk if it is installed on a motherboard with SATA-300 ports. The correct setting of this jumper is very important and will describe in detail in the next page.
Installing a SATA hard disk is therefore very simple: remove or change the jumper SATA-150/300 (if your disk has this jumper, will talk about setting this jumper on the next page), connect the cable Serial ATA data and power cable with your computer turned off. This is all you need to do.
Jumper SATA-150/SATA-300
As some hard drives SATA-300 do not work properly on motherboards with SATA-150 ports, some have a jumper SATA-150/SATA-300 (also known as jumper 1.5 Gbps / 3 Gbps). The problem is that by default this jumper is set to position "SATA-150", thus limiting the performance of hard disk if it is installed on a motherboard with SATA-300 ports. We will show you the performance impact caused by wrong configuration of a SATA-300 below.
So before installing a SATA-300 hard drive you should check if it has a jumper SATA-150/SATA-300 and if this jumper is set in the correct position: If you have an old motherboard with SATA-150 you should maintain this position jumper on SATA-150, but if your motherboard has SATA-300 - as with almost all motherboards on the market today - you should move it to position "SATA-300". This information can usually be found on the label of the hard disk.
This particular hard drive (a Seagate Barracuda 7200.10 160 GB) comes with a jumper limiting the performance of the disk at 150 MB / s (1.5 Gbps), see Figure 9. To make it work properly as a SATA-300 device must remove this jumper (see diagram in Figure 8). In this case the jumper can be removed with a small screwdriver, small pliers or tweezers. Note that depending on the model of hard drive you can move the position of this jumper instead of removing it. So it is very important that you pay attention to what is written on the label of your hard drive.
What is the performance impact of a hard disk SATA-300 configured incorrectly? We did some tests to verify this. We measured the throughput of our Seagate Barracuda 7200.10 160 GB with three programs different: SpeedDisk32, HD Tach and HD Tune. We started the test with the jumper in its default configuration (SATA-150 ") and then removed it, which meant that the disk device actually works as a SATA-300.
As you can see the results in all three programs show the same thing. Although the transfer rates of maximum and minimum average remained the same, with the jumper in position-300 SATA transfer rate of pressure increased from 60% to 69%.
In short, do not forget to verify the existence and correct configuration of this jumper when installing hard drives SATA-300!
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