【REVIEW】 now, SATA interface, a variety of storage devices has become the "new favorite", SATA hard drives PATA hard drive to replace a desktop hard drive mainstream SATA drive interface is also moving closer. However, the external storage device (such as mobile hard disk) interface is still widely used USB2.0 or IEEE1394, although the two interface data transfer rate up to a 480Mpbs/400Mbps, but they do not play hard drive and other equipment, the greatest potential. This is because the mobile hard disk USB2.0 or IEEE1394 bridge chip must be used to implement the interface of the conversion, this connection will undoubtedly affect the device performance. Now, eSATA interface, there, it also brings us "flying" general feeling.
Now, SATA interface, a variety of storage devices have gradually become the "new favorite", SATA hard drives PATA hard drive to replace a desktop hard drive mainstream SATA drive interface is also moving closer. However, the external storage device (such as mobile hard disk) interface is still widely used USB2.0 or IEEE1394, although the two interface data transfer rate up to a 480Mpbs/400Mbps, but they do not play hard drive and other equipment, the greatest potential. This is because the mobile hard disk USB2.0 or IEEE1394 bridge chip must be used to implement the interface of the conversion, this connection will undoubtedly affect the device performance. Now, eSATA interface, there, it also brings us "flying" general feeling.
What is eSATA?
eSATA stands for External Serial ATA (external serial ATA), which is the standard SATA interface, the external expansion. In other words, eSATA is the "external" version of the SATA, which is used to connect an external rather than internal SATA devices. For example, has a eSATA interface, you can easily SATA hard drive with eSATA interface to connect the motherboard, rather than replace the SATA hard drive to open the case.
Relative to the SATA interface to it, eSATA some changes in the hardware specifications of the data line interface to install a metal shrapnel Department to ensure the physical connection of firmness. The original L-shaped plug SATA is the use of different interfaces direction, while the eSATA is up and down through the plug end of a different thickness and groove to prevent accidental interpolation, it also supports hot-swappable. Although the change in the interface methods, but the underlying physical eSATA specification did not change, still using the 7-pin data cable, so only need to change the interface, can achieve the compatibility of SATA devices.
eSATA interface (left) is flat, while the SATA interface is L-shaped
Ordinary 3.5-inch hard drive maximum data transfer rate of 60MB / s, using the external 3.5-inch hard disk box when, USB2.0 or IEEE 1394 interface data transfer speed will be the bottleneck. If you use an external RAID 0 storage device, then the maximum bandwidth of 480Mbps interface will severely limit the performance of the hard disk to play. Therefore, eSATA is a very good solution. And eSATA HDD Enclosure with SATA hard disk in the middle no bridge chip conversion, is a native storage device interface.
What features eSATA?
While eSATA is an extension of SATA interfaces, and the manufacturer does not need to SATA protocol and the processing chip to make any changes, but to ensure the safe move SATA chassis, the SATA-IO through the audit of international organizations, there must be many local needs to be improved.
eSATA interface, the first feature is the need to provide hot swap. In addition to the current old serial, parallel, external interface, such as PC, the other including USB, IEEE1394 interface, including many of the technical support hot swap, and eSATA for storage devices such specialized services to support hot swap the meaning of the interface is more important . You might ask, SATA hot swap specification is not already included technology? Why eSATA also need to increase the same thing? In fact, the existing number of motherboard SATA 1.0 standard controller does not support hot swap functionality, when the user is running in the system will disconnect when the SATA device is likely to cause system crashes. To solve this problem, SATA 2.5 specification on the hot-plug the security and reliability have made further strengthened.
ESATA interfaces on the motherboard
In addition to strengthening the normative hot swappable, eSATA interfaces must be redesigned to meet the requirements of the external connection. Original SATA cable inside the chassis and interfaces without any protection and locking devices, while the joints are very fragile. In general, the internal chassis plug SATA interface is about 50 times easier to problems due to poor contact and so that the interface design, for external devices is undoubtedly fatal! After all, no one wanted to own a few times or eSATA hard drives in plug abandoned after minor collisions.
As an external connection standard, eSATA need strength, resistance to electromagnetic interference, all the cables meet the requirements in terms of flexibility. Therefore, eSATA device interface and cable are used all-metal shielding. Full metal shielding design can not only reduce the electromagnetic interference, but also help to reduce the static electricity produced during hot swap. At the same time, to prevent accidental disconnect interfaces are external, eSATA standard also requires the installation of cable interfaces shrapnel style metal locking device. According to the test, eSATA interface, the new design will ensure that equipment can be at least 2,000 hot-plug.
eSATA port complex is also able to chip in a SATA channels provide up to 4 SATA interfaces. As the SATA 2.5 specification SATA interface transfer rate of 300MB / s, while today's fastest SATA hard drive only the internal transfer rate 80MB / s. By a simple port multiplexing chip, a SATA channel 4 eSATA devices can be shared to achieve higher connection density. Of course, sharing the same channel eSATA storage devices can not be accumulated over a maximum transfer rate of 300MB / s.
Finally, eSATA interfaces also need to PCB layout and power aspects of the standard to be promulgated by the SATA-IO eSATA certification mark. This stage, although most of the SATA hard drive can work in the eSATA interface, but because there is no corresponding protection case and power supply system, which exposed the hard drive is prone to failure. SATA-IO recommends that users try to purchase certified eSATA external storage device and board.
Where is the advantage of eSATA is reflected in
And common external USB2.0 and IEEE1394 interface, compared to two common, eSATA biggest advantage is the data transmission capacity. theory eSATA 1.5Gbps transfer rate up to or 3Gbps, much higher than the 480Mbps USB2.0 and IEEE 1394's 400Mbps. In the actual test, from the size of the computer to copy a 1.36GB file to a different interface to external storage devices, eSATA interface, the time-consuming equipment is far less than USB2.0 or IEEE 1394 device, nearly faster times. With the emergence of eSATA, the external interface transfer rate for the first time such equipment is far greater than the internal hard drive transfer rate.
Several major theoretical interface speed and loss of speed compared
Little Knowledge: sustained transfer rate, burst transfer rates and interface transfer rate
Parameters describing the state of hard work, many of them and performance relationship is the biggest sustained transfer rate and burst transfer rates. The former means that when hard work, you can speed up a long time stability (similar to athletes in endurance); the latter can be achieved in an instant to drive the maximum transmission rate (the equivalent explosive force), continuing the hard disk transfer rate depends on the mechanical structure , and burst transfer rates between the hard disk cache has a lot.
And compared these two parameters, interface transfer rate is more like a standard, it provides hard data devices such as the transmission speed limit, it is like the highway speed limit signs. Hard at work, sustained transfer rate is less than interface transfer rate, burst transfer rate may be close to the maximum interface transfer rate, but the duration will not be long.
In achieving cost, eSATA is undoubtedly an advantage. The traditional USB or IEEE 1394 external devices, through USB or IEEE 1394 interfaces to read and write data from the hard disk, you must use an interface circuit, while the cost of this conversion circuit 5 to 10 dollars. In addition, the interface converter's delay on the data transmission speed of a great impact, which was tested, IEEE 1394 rate of loss (loss of speed than the peak velocity) reached 20%, USB1.0 and USB2.0 33%, respectively and 25%, while the rate of loss of SATA 0, SATA and PATA This is because the same are based on the ATA protocol, so in the transmission process does not require protocol conversion, it will not only cost savings, and hard drive performance is not!
eSATA will give us?
SATA interface for eSATA born out of excellent features, it also developed many new application, the most meaningful program is through the built-in eSATA SATA hard drives and external hard drives set up RAID 1 system, backup data quickly and completely. The past, users have to set up RAID 1 system, must be installed in the chassis, the same two-capacity hard drive. Now with eSATA interfaces, RAID 1 implementation can be more flexible. For example, users need to backup data in the time, just plug in the eSATA drive interface, and simple settings in the BIOS can not reduce the operating speed of access to a backup storage of data in exactly the same. End-users only need to connect eSATA external hard drive interface disconnect, to complete the entire backup process. And previous RAID 1 is different, so the backup at any time according to user needs, backup hard drive can keep out of other PC connected to read data.
In addition, with the Blu-ray recorders and other devices appear, the original USB 2.0, IEEE1394 interface, apparently unable to meet the data recording device on demand, produce burning failure is common. With eSATA interface, external drive can easily access and built-in optical drive the same performance and stability, a fundamental solution to the external transfer rate of optical storage devices, slow, poor stability problems.
It is particularly worth mentioning is that, eSATA to SATA safe hot swappable storage devices also have the opportunity with large capacity and low price of occupation of near-line and offline storage market. Users need only plug in the eSATA drive on these servers, will be able to rapidly increase the total storage capacity of 500GB, or even more, and the whole process need not restart the computer.
Written in the last
Present, including Seagate, etc., many storage vendors are beginning to shift their focus external hard drive. At CES2006, the Seagate on the display of the newly developed series of external hard disk eSATA Pushbutton Back-up, including the interface 500GB capacity product speeds of up to 300MB / s. In addition, Data-Tec, IO DATA and other companies have launched their own eSATA external hard drive or DVD recorder, at the same time, the market also appeared with the eSATA interface board products, such as ASRock's 775XFire-eSATA2, ASUS's P5W DH so.
Seagate's eSATA external hard drive
Despite the technical advantages eSATA prominent, but there are also some shortcomings, as it only provides a data interface, the lack of power supply (all based on eSATA interface devices have to use an external power supply). However, we have reason to believe that, with the eSATA technology continues to improve, and SATA hard drives, Blu-ray, HD DVD high bandwidth requirements of interfaces such as the growing number of equipment, eSATA external storage devices will become an important interface standard.