The serial ATA (serial advanced technology attachm
ent), or SATA computer bus, is a storage-interface for connecting host bus adapters to mass storage devices such as hard disk drives and optical drives. The SATA host adapter is integrated into almost all modern consumer laptop computers and desktop motherboards.
Serial ATA was designed to replace the older ATA (AT Attachment) standard (also known as EIDE). It is able to use the same low level commands, but serial ATA host-adapters and devices communicate via a high-speed serial cable over two pa
irs of conductors. In contrast, the parallel ATA (the redesignation for the legacy ATA specifications) used 16 data conductors each operating at a much lower speed.
SATA offers several compelling advantages over the older parallel ATA (PATA) interface: reduced cable-bulk and cost (reduced from eighty wires to seven), faster and more efficient data transfer, and hot swapping.
Features
Hotplug
All SATA devices support hotplugging. However, proper hotplug support requires the device be running in its native command mode not via IDE emulation, which requires AHCI (Advanced Host Controller Interface). Some of the earliest SATA host adapters were not capable of this and furthermore some older operating systems, such as Windows XP, do not directly support AHCI.
Advanced Host Controller Interface
As their standard interface, modern SATA controllers use the AHCI (Advanced Host Controller Interface), allowing advanced features of SATA such as hotplug and native command queuing (NCQ). If AHCI is not enabled by the motherboard and chipset, SATA controllers typically operate in "IDE emulation" mode which does not allow features of devices to be accessed if the ATA/IDE standard does not support them.
Windows device drivers that are labeled as SATA are usually running in IDE emulation mode unless they explicitly state that they are AHCI mode or in RAID mode. While the drivers included with Windows XP do not support AHCI, AHCI has been implemented by proprietary device drivers. Windows, Windows 7, FreeBSD, Linux with kernel version 2.6.19 onward as well as Solaris and OpenSolaris have native support for AHCI.
ent), or SATA computer bus, is a storage-interface for connecting host bus adapters to mass storage devices such as hard disk drives and optical drives. The SATA host adapter is integrated into almost all modern consumer laptop computers and desktop motherboards.Serial ATA was designed to replace the older ATA (AT Attachment) standard (also known as EIDE). It is able to use the same low level commands, but serial ATA host-adapters and devices communicate via a high-speed serial cable over two pa
irs of conductors. In contrast, the parallel ATA (the redesignation for the legacy ATA specifications) used 16 data conductors each operating at a much lower speed.SATA offers several compelling advantages over the older parallel ATA (PATA) interface: reduced cable-bulk and cost (reduced from eighty wires to seven), faster and more efficient data transfer, and hot swapping.
Features
Hotplug
All SATA devices support hotplugging. However, proper hotplug support requires the device be running in its native command mode not via IDE emulation, which requires AHCI (Advanced Host Controller Interface). Some of the earliest SATA host adapters were not capable of this and furthermore some older operating systems, such as Windows XP, do not directly support AHCI.
Advanced Host Controller Interface
As their standard interface, modern SATA controllers use the AHCI (Advanced Host Controller Interface), allowing advanced features of SATA such as hotplug and native command queuing (NCQ). If AHCI is not enabled by the motherboard and chipset, SATA controllers typically operate in "IDE emulation" mode which does not allow features of devices to be accessed if the ATA/IDE standard does not support them.
Windows device drivers that are labeled as SATA are usually running in IDE emulation mode unless they explicitly state that they are AHCI mode or in RAID mode. While the drivers included with Windows XP do not support AHCI, AHCI has been implemented by proprietary device drivers. Windows, Windows 7, FreeBSD, Linux with kernel version 2.6.19 onward as well as Solaris and OpenSolaris have native support for AHCI.
Cables, connectors, and ports
Connectors and cables present the most visible differences between
SATA and parallel ATA drives. Unlike PATA, the same connectors are used on 3.5-inch SATA hard disks for desktop and server computers and 2.5-inch disks for portable or small computers; this allows 2.5-inch drives to be used in desktop computers with only a mounting bracket and no wiring adapter. Smaller disks may use the mini-SATA spec, suitable for small-form-factor Serial ATA drives and mini SSDs.
There is a special connector (eSATA) specified for external devices, and an optionally implemented provision for clips to hold internal connectors firmly in place. SATA drives may be plugged into SAS controllers and communicate on the same physical cable as native SAS disks, but SATA controllers cannot handle SAS disks.
There are SATA ports (on motherboards of a PC) that can use SATA data cable with locks or clips, thus, reducing the chance of accidentally unplugging while the PC is turned on. So does the same with SATA power connector and SATA data connector connected to a SATA HDD or SATA optical drive . Also, the
Connectors and cables present the most visible differences between
SATA and parallel ATA drives. Unlike PATA, the same connectors are used on 3.5-inch SATA hard disks for desktop and server computers and 2.5-inch disks for portable or small computers; this allows 2.5-inch drives to be used in desktop computers with only a mounting bracket and no wiring adapter. Smaller disks may use the mini-SATA spec, suitable for small-form-factor Serial ATA drives and mini SSDs.There is a special connector (eSATA) specified for external devices, and an optionally implemented provision for clips to hold internal connectors firmly in place. SATA drives may be plugged into SAS controllers and communicate on the same physical cable as native SAS disks, but SATA controllers cannot handle SAS disks.
There are SATA ports (on motherboards of a PC) that can use SATA data cable with locks or clips, thus, reducing the chance of accidentally unplugging while the PC is turned on. So does the same with SATA power connector and SATA data connector connected to a SATA HDD or SATA optical drive . Also, the
re are right-angled and left-angled connectors only on one end of SATA data cable, which can only be used when connecting to a SATA HDD or SATA optical drive.
Comparisons between SATA and SCSI
SCSI currently offers transfer rates higher than SATA, but it uses a more complex bus, usually resulting in higher manufacturing costs. SCSI buses also allow connection of several drives (using multiple channels, 7 or 15 on each channel), whereas SATA allows one drive per channel, unless using a port multiplier.
SATA 3 Gbit/s offers a maximum bandwidth of 300 MB/s per device compared to SCSI with a maximum of 320 MB/s. Also, SCSI drives provide greater sustained throughput than SATA drives because of disconnect-reconnect and aggregating performance. SATA devices generally link compatibly to SAS enclosures and adapters, while SCSI devices cannot be directly connected to a SATA bus.
SCSI, SAS and fibre-channel (FC) drives are typically more expensive so they are traditionally used in servers and disk arrays where the added cost is justifiable. Inexpensive ATA and SATA drives evolved in the home-computer market hence there is a view that they are less reliable. As those two worlds overlapped, the subject of reliability became somewhat controversial. Note that, generally, the failure rate of a disk drive is related to the quality of its heads, platters and supporting manufacturing processes, not to its interface.
Difference between IDE, SCSI and SATA
Integrated Drive Electronics (IDE) is one of the oldest interfaces for hard drives, marking a new era in computer history. It was the first interface to make hard drives affordable for everyone. The most prominent feature of IDE is that there was little cabling when hooking up a hard drive to the computer, which led to a hassle-free setup. IDE was introduced in 1986 Compaq computers.
SCSI currently offers transfer rates higher than SATA, but it uses a more complex bus, usually resulting in higher manufacturing costs. SCSI buses also allow connection of several drives (using multiple channels, 7 or 15 on each channel), whereas SATA allows one drive per channel, unless using a port multiplier.
SATA 3 Gbit/s offers a maximum bandwidth of 300 MB/s per device compared to SCSI with a maximum of 320 MB/s. Also, SCSI drives provide greater sustained throughput than SATA drives because of disconnect-reconnect and aggregating performance. SATA devices generally link compatibly to SAS enclosures and adapters, while SCSI devices cannot be directly connected to a SATA bus.
SCSI, SAS and fibre-channel (FC) drives are typically more expensive so they are traditionally used in servers and disk arrays where the added cost is justifiable. Inexpensive ATA and SATA drives evolved in the home-computer market hence there is a view that they are less reliable. As those two worlds overlapped, the subject of reliability became somewhat controversial. Note that, generally, the failure rate of a disk drive is related to the quality of its heads, platters and supporting manufacturing processes, not to its interface.
Difference between IDE, SCSI and SATA
Integrated Drive Electronics (IDE) is one of the oldest interfaces for hard drives, marking a new era in computer history. It was the first interface to make hard drives affordable for everyone. The most prominent feature of IDE is that there was little cabling when hooking up a hard drive to the computer, which led to a hassle-free setup. IDE was introduced in 1986 Compaq computers.
Small Computer System Interface (SCSI) is a standard amongst certain devices that can be connected to a computer, such as hard drives. SCSI was introduced in 1986 as a component of Apple and Amiga computers. The basic idea was to give a faster alternative to Integrated Drive Electronics (IDE) and present an interface which almost any device can be designed to communicate with. Hard drives are the most popular devices that support SCSI, since it has a much higher bandwidth capacity than IDE. However, this high bandwidth capacity comes at a price. Most people do not find such hard drives worth the expense. Those who do invest plenty of money in SCSI hard drives are usually data centers and large companies that host their own servers.
The advent of Serial AT Attachment (SATA) in 2003 was successful and quickly became affordable to the public. The specific design of SATA was to beat the IDE benchmarks and render IDE obsolete. Its first release had a 1.5 GB/s throughput, and new versions of it just keep coming. The high bandwidth and affordability makes it perfect for home users and data centers alike. After SATA was introduced, motherboard manufacturers quickly put aside IDE and gave more importance to SATA technology.
Nice Post. SATA's hard drives performance is good.
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