NationMaster - Encyclopedia: Serial ata

Serial Advanced Technology Attachment (SATA, IPA: /ˈseɪtə/, /ˈsætə/ or 'sɑːtə) is a computer bus primarily designed for transfer of data between a computer and mass storage devices such as hard disk drives and optical drives. SATA or Sata can refer to: Serial ATA, a computer bus technology for connecting hard disks and other devices SATA International, an airline based in Ponta Delgada, the Azores, Portugal Michael Sata, leader of the Patriotic Front of Zambia Sata, a traditional dish from the Malaysian state of Terengganu Category... ImageMetadata File history File links Download high resolution version (766x683, 135 KB) Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... A motherboard is the central or primary circuit board making up a complex electronic system, such as a modern computer. ... In telecommunications and computer science, serial communications is the process of sending data one bit at one time, sequentially, over a communications channel or computer bus. ... In computer architecture, a bus is a subsystem that transfers data or power between computer components inside a computer or between computers and typically is controlled by device driver software. ... Many different consumer electronic devices can store data. ... A hard disk drive (HDD), commonly referred to as a hard drive, hard disk or fixed disk drive,[1] is a non-volatile storage device which stores digitally encoded data on rapidly rotating platters with magnetic surfaces. ... Optical Storage is made possible by data storage devices such as optical discs and holographic storage systems. ...

The main advantages over the older parallel ATA interface are faster data transfer, ability to remove or add devices while operating (hot swapping), thinner cables that let air cooling work more efficiently, and more reliable operation with tighter data integrity checks. ATA connector on the left, with two motherboard ATA connectors on the right. ... The movement of data from one location to another is called data transfer. ... Hot swapping or hot plugging is the ability to remove and replace components of a machine, usually a computer, while it is operating. ...

It was designed as a successor to the Advanced Technology Attachment standard (ATA), and is expected to eventually replace the older technology (retroactively renamed Parallel ATA or PATA). Serial ATA adapters and devices communicate over a high-speed serial cable. ATA connector on the left, with two motherboard ATA connectors on the right. ... A retronym is a type of neologism coined for an old object or concept whose original name has come to be used for something else, is no longer unique, or is otherwise inappropriate or misleading. ... In telecommunications and computer science, serial communications is the process of sending data one bit at one time, sequentially, over a communications channel or computer bus. ...

Advanced Host Controller Interface

The standard interface for SATA controllers is Advanced Host Controller Interface (AHCI), which allows advanced features of SATA such as hot plug 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 that are not supported by the ATA/IDE standard. Windows device drivers that are labeled as SATA are usually running in IDE emulation mode unless they explicitly state that they are AHCI. While the drivers included with Windows XP do not support AHCI, AHCI has been implemented by proprietary device drivers.^[1] Windows Vista and the current versions of Mac OS X and Linux [1] have native support for AHCI.^{[citation needed]} The Advanced Host Controller Interface (AHCI) is a hardware mechanism that allows software to communicate with Serial ATA (SATA) devices such as host bus adapters which are designed to offer features not offered by Parallel ATA (PATA) controllers besides higher speeds, such as hot-plugging and native command queuing. ... The Advanced Host Controller Interface (AHCI) is a hardware mechanism that allows software to communicate with Serial ATA (SATA) devices such as host bus adapters which are designed to offer features not offered by Parallel ATA (PATA) controllers besides higher speeds, such as hot-plugging and native command queuing. ... Hot swapping is the ability to remove and replace components of a machine, usually a computer, while it is operating. ... Native Command Queuing (NCQ) is a technology designed to increase performance of SATA hard disks by allowing the individual hard disk to receive more than one I/O request at a time and dynamically change the order in which they are applied. ... Windows XP is a line of operating systems developed by Microsoft for use on personal computers, including home and business desktops, notebook computers, and media centers. ... Windows Vista (pronounced ) is a line of operating systems developed by Microsoft for use on personal computers, including home and business desktops, laptops, Tablet PCs, and media centers. ... Mac OS X (pronounced ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ... This article is about operating systems that use the Linux kernel. ...

Features

The current SATA specification can support data transfer rates as high as 3.0 Gbit/s per device. SATA uses only 4 signal lines; cables are more compact and cheaper than for PATA. SATA supports hot-swapping and NCQ. 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 Serial Attached SCSI (SAS) controllers and communicate on the same physical cable as native SAS disks, but SATA controllers cannot handle SAS disks. Hot swapping or hot plugging is the ability to remove and replace components of a machine, usually a computer, while it is operating. ... Native Command Queuing (NCQ) is a technology designed to increase performance of SATA hard disks by allowing the individual hard disk to receive more than one I/O request at a time and dynamically change the order in which they are applied. ... 2. ...

Throughput

SATA 1.5 Gbit/s

First-generation SATA interfaces, also known as SATA/150 or unofficially as SATA 1, communicate at a rate of 1.5 gigabits per second (Gbit/s). Taking into account 8b10b coding overhead, the actual uncoded transfer-rate is 1.2 Gbit/s, or 1,200 megabits per second (Mbit/s). The theoretical burst throughput of SATA/150 is similar to that of PATA/133, but newer SATA devices offer enhancements such as NCQ which improve performance in a multitasking environment. Data transfer rates are limited by mechanical hard drives themselves, not the interfaces: the fastest modern desktop hard drives transfer data at a maximum of about 120 MB/s,^[2] which is well within the capabilities of even the older PATA/133 specification. A gigabit per second (Gbps or Gbit/s) is a unit of data transmission equal to 1,000 megabits per second or 1,000,000 kilobits per second or 1,000,000,000 bits per second. ... A gigabit is a unit of information or computer storage, abbreviated Gbit or sometimes Gb. ... In telecommunications, 8b/10b is a line code that maps 8-bit symbols to 10-bit symbols to achieve DC-balance (see DC coefficient) and bounded disparity, and yet provide enough state changes to allow reasonable clock recovery. ... In telecommunications and computing, bit rate (sometimes written bitrate) is the frequency at which bits are passing a given (physical or metaphorical) point. It is quantified using the bit per second (bit/s) unit. ... The Megabit is a unit of information storage, abbreviated Mbit or sometimes Mb. ... ATA connector on the left, with two motherboard ATA connectors on the right. ... Native Command Queuing (NCQ) is a technology designed to increase performance of SATA hard disks by allowing the individual hard disk to receive more than one I/O request at a time and dynamically change the order in which they are applied. ... Typical hard drives of the mid-1990s. ... This article is about a unit of data. ...

During the initial period after SATA/150's finalization adapter and drive manufacturers used a "bridge chip" to convert existing PATA designs for use with the SATA interface.^{[citation needed]} Bridged drives have a SATA connector, may include either or both kinds of power connectors, and generally perform identically to their PATA equivalents. Most lack support for some SATA-specific features such as NCQ. Bridged products gradually gave way to native SATA products.^{[citation needed]} Native Command Queuing (NCQ) is a technology designed to increase performance of SATA hard disks by allowing the individual hard disk to receive more than one I/O request at a time and dynamically change the order in which they are applied. ...

SATA 3.0 Gbit/s

Soon after SATA/150's introduction a number of shortcomings were observed. At the application level SATA could only handle one pending transaction at a time, like PATA; the SCSI interface has long been able to accept multiple outstanding requests and service them in the order which minimizes response time. This feature, Native Command Queuing (NCQ), was adopted as an optional supported feature for SATA 1.5 Gbit/s and SATA 3.0 Gbit/s devices. Scuzzy redirects here. ... Native Command Queuing (NCQ) is a technology designed to increase performance of SATA hard disks by allowing the individual hard disk to receive more than one I/O request at a time and dynamically change the order in which they are applied. ...

First-generation SATA devices were at best a little faster than parallel ATA/133 devices. A 3 Gbit/s signaling rate was added to the Physical layer (PHY layer), effectively doubling maximum data throughput from 150 MB/s to 300 MB/s. SATA/300's transfer rate is expected to satisfy drive throughput requirements for some time, as the fastest desktop hard disks barely saturate a SATA/150 link. A SATA data cable rated for 1.5 Gbit/s will handle current second-generation SATA 3.0 Gbit/s drives without any loss of sustained and burst data transfer performance. This article does not cite any references or sources. ... In communication networks, throughput is the amount of digital data per time unit that is delivered over a physical or logical link, or that is passing through a certain network node. ...

Backward compatibility between SATA 1.5 Gbit/s controllers and SATA 3.0 Gbit/s devices was important, so SATA/300's autonegotiation sequence is designed to fall back to SATA/150 speed (1.5 Gbit/s rate) when in communication with such devices. In practice, some older SATA controllers do not properly implement SATA speed negotiation. Affected systems require the user to set the SATA 3.0 Gbit/s peripherals to 1.5 Gbit/s mode, generally through the use of a jumper.^[3] Chipsets known to have this fault include the VIA VT8237 and VT8237R south bridges, and the VIA VT6420 and VT6421L standalone SATA controllers.^[4] SiS's 760 and 964 chipsets also initially exhibited this problem, though it can be rectified with an updated SATA controller ROM.^{[citation needed]} This article does not cite any references or sources. ...

This table shows the real speed of SATA 1.5 Gbit/s and SATA 3 Gbit/s (note the bottom row shows megabytes per second (MB/s, not Mbit/s):

SATA II Misnomer

The 3.0 Gbit/s specification has been widely referred to as "Serial ATA II" ("SATA II" or "SATA2"), contrary to the wishes of the Serial ATA International Organization (SATA-IO) which defines the standard. SATA II was originally the name of a committee defining updated SATA standards, of which the 3 Gbit/s standard was just one. However since it was among the most prominent features defined by the former SATA II committee, the name SATA II became synonymous with the 3 Gbit/s standard, so the group has since changed names to the Serial ATA International Organization, or SATA-IO, to avoid further confusion.

SATA 6.0 Gbit/s

SATA's roadmap includes plans for a 6.0 Gbit/s standard. In current PCs, SATA 3.0 Gbit/s already greatly exceeds the sustainable (non-burst) transfer rate of even the fastest hard disks. The 6.0 Gbit/s standard is useful right now in combination with port multipliers, which allow multiple drives to be connected to a single Serial ATA port, thus sharing the port's bandwidth with multiple drives.^[5] Solid-state drives may also one day make use of the faster transfer rate. This article refers to both flash and DRAM-based solid state drives. ...

Cables and connectors

Connectors and cables are the most visible difference between SATA and Parallel ATA drives. Unlike PATA, the same connectors are used on 3.5-in (90 mm) SATA hard disks for desktop and server computers and 2.5-in (70 mm) disks for portable or small computers; this allows 2.5" drives to be used in desktop computers without the need for wiring adapters (a mounting adaptor is still likely to be needed to securely mount the drive).

SATA power connectors and data connectors have been criticized for their fragility and poor robustness — the thin plastic tops of the connectors (see power connector picture at right) can easily break due to shearing force when the user pulls the plug at a non-orthogonal angle, as can the connectors on drives they connect to.^{[dubious – discuss]} In the case of a broken connector on a hard drive, this could result in a complete loss of access to all data stored on the drive.

Data

The SATA standard defines a data cable with seven conductors (3 grounds and 4 active data lines in two pairs) and 8 mm wide wafer connectors on each end. SATA cables can be up to 1 m (39 in) long, and connect one motherboard socket to one hard drive. PATA ribbon cables, in comparison, connect one motherboard socket to up to two hard drives, carry either 40- or 80-conductor wires, and are limited to 45 cm (18 in) in length by the PATA specification (however, cables up to 90 cm (36 in) are readily available). Thus, SATA connectors and cables are easier to fit in closed spaces and reduce obstructions to air cooling. They are more susceptible to accidental unplugging and breakage than PATA, but cables can be purchased that have a 'locking' feature, whereby a small (usually metal) spring holds the plug in the socket. Wikipedia does not have an article with this exact name. ... Left: 20-way grey ribbon cable with wire no. ... Air cooling is a method of dissipating heat. ...

Parallel ATA uses single-ended signalling. In this system, the noise combines with the data signal during the signal transmission. Noise causes significant interference with the data signal at higher speeds. In order to reduce the noise interference, the driving voltage of Parallel ATA is as high as 5 V. Although the higher voltage can reduce the noise interference, the 5 V is too high for modern high speed silicon devices. Thus the fabrication cost of driving ICs is higher, and the speed is limited in comparison to low voltage silicon ICs. Single-ended signalling is the simplest method of transmitting electrical signals over wires. ...

In comparison, SATA systems use differential signaling. In this system, it is easy to filter out the noise from the data signal at the receiving end. The higher noise rejection allows the SATA system to use only 500 mV peak-to-peak differential voltage to carry the signal at higher speeds without distortion or noise interference. It has been suggested that this article or section be merged into Low voltage differential signaling. ...

Compared with the 5 V driving voltage in PATA ribbon cables, the 0.5 V in SATA cables in theory make the SATA system much more power efficient. However most SATA chipsets need significantly more power than PATA chipsets, due to the faster required encoding per wire.

Power

The SATA standard also specifies a new power connector. Like the data cable, it is wafer-based, but its wider 15-pin shape prevents accidental misidentification and forced insertion of the wrong connector type. Native SATA devices favor the SATA power-connector over the old four-pin Molex connector (found on all PATA equipment), although some SATA drives retain older 4-pin Molex. Information from the Fujitsu Serial ATA Interface for Mobile Hard Disk Drives whitepaper [1]. Note that staggered spinup of disks is not confined solely to mobile drives, and is a feature of many multi-drive systems using RAID: Staggered spin-up is a simple mechanism by which the storage subsystem... This is a file from the Wikimedia Commons, a repository of free content hosted by the Wikimedia Foundation. ... A power connector is an electrical connector designed to carry a significant amount of electrical power, usually as DC or low-frequency AC. Some types of RF connector may also carry large amounts of power, but are considered as a separate category. ... A Molex connector is the vernacular term for a two-piece pin and socketinterconnection. ...

Adaptors are available to convert a 4-pin Molex connector to a SATA power connector. However, because the 4-pin Molex connectors do not provide 3.3 V power, these adapters provide only 5 V and 12 V power and leave the 3.3 V lines unconnected. This precludes the use of such adapters with drives that require 3.3 V power. Understanding this, drive manufacturers have largely left the 3.3 V power lines unused. However, without 3.3 V power, the SATA device may not be able to implement hotplugging as mentioned in the previous paragraph. International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ... Josephson junction array chip developed by NIST as a standard volt. ... For other uses, see Ampere (disambiguation). ... Hot swapping or hot plugging is the ability to remove and replace components of a machine, usually a computer, while it is operating. ... Information from the Fujitsu Serial ATA Interface for Mobile Hard Disk Drives whitepaper [1]. Note that staggered spinup of disks is not confined solely to mobile drives, and is a feature of many multi-drive systems using RAID: Staggered spin-up is a simple mechanism by which the storage subsystem... A Molex connector is the vernacular term for a two-piece pin and socketinterconnection. ... Hot swapping or hot plugging is the ability to remove and replace components of a machine, usually a computer, while it is operating. ...

Topology

SATA is a point to point architecture. The connection between the controller and the storage device is direct.

In a modern PC system, the SATA controller is usually found on the motherboard, or installed in a PCI slot. Some SATA controllers have multiple SATA ports and can be connected to multiple storage devices. There are also port expanders which allow multiple storage devices to be connected to a single SATA controller port.

Encoding

These high-speed transmission protocols use a logic encoding known as 8b10b. The signal is sent using Non-return to Zero (NRZ) encoding with Low Voltage Differential Signaling (LVDS). In telecommunications, 8b/10b is a line code that maps 8-bit symbols to 10-bit symbols to achieve DC-balance (see DC coefficient) and bounded disparity, and yet provide enough state changes to allow reasonable clock recovery. ... Contrast with: return-to-zero. ... Low voltage differential signaling, or LVDS, is an electrical signaling system that can run at very high speeds over cheap, twisted-pair copper cables. ...

In the 8b10b encoding the synchronizing signal is included in the data sequence. This technique is known as Clock Data Recovery, because it doesn't use a separate synchronizing signal. Instead, it uses the serial signal's 0 to 1 transitions to recover the clock signal. In telecommunications, 8b/10b is a line code that maps 8-bit symbols to 10-bit symbols to achieve DC-balance (see DC coefficient) and bounded disparity, and yet provide enough state changes to allow reasonable clock recovery. ... Some digital data streams, especially high-speed serial data streams (such as the raw stream of data from the magnetic head of a disk drive) are sent without an accompanying clock. ...

External SATA

Standardized in mid-2004, eSATA defined separate cables, connectors, and revised electrical requirements for external applications: This is the official eSATA logo. ... This is the official eSATA logo. ...

Aimed at the consumer market, eSATA enters an external storage market already served by the USB and FireWire interfaces. Most external hard disk drive cases with FireWire or USB interfaces use either PATA or SATA drives and "bridges" to translate between the drives' interfaces and the enclosures' external ports, and this bridging incurs some inefficiency. Some single disks can transfer almost 120 MB/s during real use,^[2] more than twice the maximum transfer rate of USB 2.0 or FireWire 400 (IEEE 1394a) and well in excess of the maximum transfer rate of FireWire 800, though the S3200 FireWire 1394b spec reaches ~400 MB/s (3.2Gb/s). Finally, some low-level drive features, such as S.M.A.R.T., may not be available through USB or FireWire bridging.^[6] eSATA does not suffer from these issues. Josephson junction array chip developed by NIST as a standard volt. ... Note: USB may also mean upper sideband in radio. ... The 6-pin and 4-pin FireWire 400 Connectors The alternative ethernet-style cabling used by 1394c FireWire is Apple Inc. ... Electrostatic discharge (ESD) is the sudden and momentary electric current that flows between two objects at different electrical potentials. ... Electromagnetic interference (or EMI, also called radio frequency interference or RFI) is a (usually undesirable) disturbance caused in a radio receiver or other electrical circuit by electromagnetic radiation emitted from an external source. ... The 6-pin and 4-pin FireWire Connectors FireWire is Apple Inc. ... The 6-pin and 4-pin FireWire 400 Connectors The alternative ethernet-style cabling used by 1394c FireWire is Apple Inc. ... Self-Monitoring, Analysis, and Reporting Technology, or S.M.A.R.T., is a monitoring system for computer hard disks to detect and report on various indicators of reliability, in the hope of anticipating failures. ...

It is likely that eSATA co-exists with USB 2.0 and FireWire external storage for several reasons. As of early 2008 the vast majority of mass-market computers have USB ports and many computers and consumer electronic appliances have FireWire ports, but few devices have external SATA connectors. For small form-factor devices (such as external 2.5" (70 mm) disks), a PC-hosted USB or FireWire link supplies sufficient power to operate the device. Where a PC-hosted port is concerned, eSATA connectors cannot supply power, and would therefore be more cumbersome to use. Sky HD is the brand name of the HDTV service launched by BSkyB on 22 May 2006 in the UK and the Republic of Ireland to enable high definition channels on Sky Digital to be viewed. ...

Desktops computers that lack a built-in eSATA interface can be upgraded with the installation of an eSATA host bus adapter (HBA), while notebooks can be upgraded with Cardbus^[7] or ExpressCard^[8] versions of an eSATA HBA. With passive adapters the maximum cable length is reduced to 1 meter due to the absence of compliant eSATA signal levels. Full SATA speed for external disks (115 MB/s) have been measured with external RAID enclosures.^{[citation needed]} In general terms, a Host Bus Adapter (HBA) is any adapter that allows a computer bus to attach to another bus or channel. ... The PCMCIA is the Personal Computer Memory Card International Association, an industry trade association that creates standards for notebook computer peripheral devices. ... ExpressCard is a hardware standard replacing PC cards (also known as PCMCIA cards), both developed by the Personal Computer Memory Card International Association (PCMCIA). ...

From the second half of 2008, SATA-IO expects eSATA to provide power to eSATA devices without the need for a separate power connection. In a news release from 2008-01-14, SATA-IO calls it the "Power Over eSATA initiative."^[9]

eSATA may be of interest to the enterprise and server market, which has already standardized on the Serial Attached SCSI (SAS) interface, because of its hotplug capability and low price. 2. ...

Prior to the final eSATA specification, there were a number of products designed for external connections of SATA drives. Some of these use the internal SATA connector or even connectors designed for other interface specifications, such as FireWire. These products are not eSATA compliant. The final eSATA specification features a specific connector designed for rough handling, similar to the regular SATA connector, but with reinforcements in both the male and female sides, inspired by the USB connector. It's harder to unplug, and can withstand yanking or wiggling which would break a male SATA connector (the hard drive or host adapter, usually fitted inside the computer). With an eSATA connector considerably more force is needed to damage the connector, and if it does break it is likely to be the female side, on the cable itself, which is relatively easy to replace.^{[citation needed]} The 6-pin and 4-pin FireWire 400 Connectors The alternative ethernet-style cabling used by 1394c FireWire is Apple Inc. ...

Backward and forward compatibility

SATA and PATA

At the device level, SATA and PATA devices are completely incompatible—they cannot be interconnected. At the application level, SATA devices are specified to look and act like PATA devices.^[10] In early motherboard implementations of SATA, backward compatibility allowed SATA drives to be used as drop-in replacements for PATA drives, even without native (driver-level) support at the operating system level. In technology, especially computing (irrespective of platform), a product is said to be backward compatible (or upward compatible) when it is able to take the place of an older product, by interoperating with other products that were designed for the older product. ...

The common heritage of the ATA command set has enabled the proliferation of low-cost PATA to SATA bridge-chips. Bridge chips were widely used on PATA drives (before the completion of native SATA drives) as well as standalone ‘dongles’. When attached to a PATA drive, a device-side dongle allows the PATA drive to function as a SATA drive. Host-side dongles allow a motherboard PATA port to function as a SATA host port.

Powered enclosures are available for both PATA and SATA drives, which interface to the PC through USB, Firewire or eSATA, with the restrictions noted above. PCI cards with a SATA connector exist that allow SATA drives to connect to legacy systems without SATA connectors. This article is about the computer bus type. ...

SATA 1.5 Gbit/s and SATA 3 Gbit/s

SATA is designed to be backward and forward compatible with future revisions of the SATA standard.^[11] Forward compatibility (sometimes confused with extensibility) is the ability of a system to accept input intended for later versions of itself. ...

According to the hard drive manufacturer Maxtor, motherboard host controllers using the VIA and SIS chipsets VT8237, VT8237R, VT6420, VT6421L, SIS760, SIS964 found on the ECS 755-A2 which was manufactured in 2003, do not support SATA 3 Gbit/s drives. To address interoperability problems, the largest hard drive manufacturer Seagate/Maxtor have added a user-accessible jumper-switch known as the Force 150, to switch between 150 MB/s and 300 MB/s operation.^[3] Users with a SATA 1.5 Gbit/s motherboard with one of the listed chipsets should either buy an ordinary SATA 1.5 Gbit/s hard disk, buy a SATA 3 Gbit/s hard disk with the user-accessible jumper, or buy a PCI or PCI-E card to add full SATA 3 Gbit/s capability and compatibility. Western Digital uses jumper setting called "OPT1 Enabled" to force 150 MB/s data transfer speed.

Comparisons with other interfaces

SATA and SCSI

SCSI currently offers transfer rates higher than SATA, but is a more complex bus usually resulting in higher manufacturing cost. Some drive manufacturers offer longer warranties for SCSI devices, however, indicating a possibly higher manufacturing quality control of SCSI devices compared to PATA/SATA devices. 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. Scuzzy redirects here. ...

SATA 3.0 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 are generally compatible with SAS enclosures and adapters, while SCSI devices cannot be directly connected to a SATA bus. 2. ...

SCSI, SAS and 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 the general opinion is that they are less reliable. As those two worlds started to overlap, the subject of reliability became somewhat controversial. It is worth noting that generally a disk drive has a low failure rate because of increased quality of its heads, platters and supporting manufacturing processes, not because of having a certain interface. Look up server in Wiktionary, the free dictionary. ... Hewlett-Packard Disk-Arrays: HASS (top) and NIKE (OEMd Data General SCSI Clariion) EMC CLARiiON CX500 (Cover removed on one Shelf) EMC Symmetrix DMX1000 A disk array is an enterprise storage system which contains multiple disk drives. ... This article is primarily about a certain class of Personal computers from the late 1970s to mid 1980s, see Domotics or Home servers for home computers used in home automation. ... A hard disk drive (HDD), commonly referred to as a hard drive, hard disk or fixed disk drive,[1] is a non-volatile storage device which stores digitally encoded data on rapidly rotating platters with magnetic surfaces. ...

eSATA in comparison to other external buses

Unlike PATA, both SATA and eSATA are designed to support hot-swapping. However, this feature requires proper support at the host, device (drive), and operating-system level. In general, all SATA/devices (drives) support hot-swapping (due to the requirements on the device-side), but requisite support is less common on SATA host adapters.^{[citation needed]} Point-to-Point telecommunications is most recently (2003) referenced regarding wireless data communications for Internet or Voice over IP via radio frequencies in the multi-gigahertz range. ... Switched Fabric is a Fibre Channel topology where many devices connect with each other via Fibre Channel switches. ... Hot swapping or hot plugging is the ability to remove and replace components of a machine, usually a computer, while it is operating. ... Fibre Channel Host Bus Adapter (64-bit PCI-X card) SCSI Host Bus Adapter (16-bit ISA card) In computer hardware, a host controller, host adapter, or host bus adapter (HBA) connects a host system (the computer) to other network and storage devices. ...

USB allows hot-swapping; this is supported by virtually every current operating system. However, USB-based storage hardware can infrequently sustain data loss when disconnected. This problem exists with media players and digital cameras using flash memory as well as mobile 2.5-inch (64 mm) USB hard drives.^{[citation needed]} Firmware damage and data loss can occasionally result from unclean spin-downs and power loss when the drive or device is removed from the USB port without first initiating a device shutdown via the computer's operating system.^[18]

SCSI devices with SCA-2 connectors are designed for hot-swapping. Many server and RAID systems provide hardware support for transparent hot-swapping. The SCSI standard prior to SCA-2 connectors was not designed for hot-swapping, but, in practice, most RAID implementations support hot-swapping of hard disks.

Contents

Advanced Host Controller Interface

Features

Throughput

SATA 1.5 Gbit/s

SATA 3.0 Gbit/s

SATA II Misnomer

SATA 6.0 Gbit/s

Cables and connectors

Data

Power

Topology

Encoding

External SATA

Backward and forward compatibility

SATA and PATA

SATA 1.5 Gbit/s and SATA 3 Gbit/s

Comparisons with other interfaces

SATA and SCSI

eSATA in comparison to other external buses

See also

Notes and references

External links

Contents

Advanced Host Controller Interface GA_googleFillSlot("encyclopedia_square");

Features

Throughput

SATA 1.5 Gbit/s

SATA 3.0 Gbit/s

SATA II Misnomer

SATA 6.0 Gbit/s

Cables and connectors

Data

Power

Topology

Encoding

External SATA

Backward and forward compatibility

SATA and PATA

SATA 1.5 Gbit/s and SATA 3 Gbit/s

Comparisons with other interfaces

SATA and SCSI

eSATA in comparison to other external buses

See also

Notes and references

External links

Advanced Host Controller Interface