SATA

SATA (hereinafter, the Serial Advanced Technology Attachment) is a computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives, optical drives, and solid-state drives. Serial ATA succeeded the older Parallel ATA (PATA) standard, offering several advantages over the older interface: reduced cable size and cost (seven conductors instead of 40 or 80), native hot swapping, faster data transfer through higher signaling rates, and more efficient transfer through an (optional) I/O queuing protocol. Although, a number of hot plug PATA offering were first invented and marketed by Core International beginning in the late 1980s for the Micro Channel architecture bus controllers.

SATA host adapters and devices communicate via a high-speed serial cable over two pairs of conductors. In contrast, parallel ATA (the redesignation for the legacy ATA specifications) uses a 16-bit wide data bus with many additional support and control signals, all operating at much lower frequency. To ensure backward compatibility with legacy ATA software and applications, SATA uses the same basic ATA and ATAPI command sets as legacy ATA devices.

SATA has replaced parallel ATA in consumer desktop and laptop computers; SATA's market share in the desktop PC market was 99% in 2008. PATA has mostly been replaced by SATA for any use; with PATA in declining use in industrial and embedded applications that use CompactFlash (CF) storage, which was designed around the legacy PATA standard. A 2008 standard, CFast to replace CompactFlash is based on SATA.

Curriculum

Main wikipage: CNM Cloud requirements

Features

Hotplug

The Serial ATA Spec requirements for SATA device hot plugging, that is, devices and motherboards that meet the specification are capable of insertion / removal of a device into / from a backplane connector (combined signal and power) that has power on. After insertion, both the Device and Host initialize and then operate normally. The powered Host or Device is not necessarily in a quiescent state.

Unlike PATA, both SATA and eSATA support hotplugging by design. However, this feature requires proper support at the host, device (drive), and operating-system levels. In general, all SATA devices (drives) support hotplugging (due to the requirements on the device-side), also most SATA host adapters support this function.

Advanced Host Controller Interface

Advanced Host Controller Interface (AHCI) is an open host controller interface published and used by Intel, which has become a de facto standard. It allows the use of 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 "IDEemulation" mode, which does not allow access to device features not supported by the ATA (also called IDE) standard.

Windows device drivers that are labeled as SATA are often running in IDE emulation mode unless they explicitly state that they are AHCI mode, in RAID mode, or a mode provided by a proprietary driver and command set that allowed access to SATA's advanced features before AHCI became popular. Modern versions of Microsoft Windows, Mac OS X, FreeBSD, Linux with version 2.6.19 onward, as well as Solaris and OpenSolaris, include support for AHCI, but older operating systems such as Windows XP do not. Even in those instances, a proprietary driver may have been created for a specific chipset, such as Intel's.

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 (89 mm) SATA hard disks (for desktop and server computers) and 2.5-inch (64 mm) disks (for portable or small computers).

Standard SATA connectors for both data and power have a conductor pitch of 1.27 mm (0.050 inches). Low insertion force is required to mate a SATA connector. A smaller mini-SATA or mSATA connector is used by smaller devices such as 1.8-inch SATA drives, some DVD and Blu-ray drives, and mini SSDs.

A special eSATA connector is 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.

Female SATA ports (on motherboards for example) are for use with SATA data cables that have locks or clips to prevent accidental unplugging. Some SATA cables have right- or left-angled connectors to ease connection to circuit boards.