A single serial ata (sata) data cable can be used to connect a motherboard slot with:

12.4.2.1 IDE/ATA/parallel ATA or PATA

IDE/ATA stands for Integrated Device Electronics/Advanced Technology Attachment. Actually, IDE is the first ANSI ATA standard or ATA-1. ATA is an open-systems standard. It was initiated by the Common Access Method (CAM) committee and later regulated by the ANSI X3 committee in 1994. Since then, several ATA versions have been released (See Table 12.16). Each version of ATA specified a protocol at a data block level, a parallel electrical interface, and a physical interface.

Table 12.16. ATA Versions [203]

The ATA specification allows no more than two storage devices per bus channel (one is the master and the other is the slave). For high-performance storage, sharing a bus channel is not preferred. Many servers have more than two ATA buses. Early ATA versions only supported HDD commands but ATA Packet Interface (ATAPI) has the similar commands as SCSI (we will discuss this in the next section), which allows CD-ROM and tape drives to use the same ATA interface. All these ATA standards are parallel ATA or PATA. PATA drives can only support a single user or personal computer environment. It focuses on low cost and low capacity rather than speed and reliability. Moreover, PATA has another issue, which is that it has too many pins for its interface connector (see Figure 12.43).

Hard Drive Controller Cards

A Serial Advanced Technology Attachment (SATA) controller card typically fits into an open PCI, PCIe, or PCI Express slot on the motherboard and includes a built-in firmware controller to run additional hard drives on the same motherboard. These cards are basically an extension of the motherboard, adding ports or slots for more hard drives. These PCI cards have transfer rate speeds of up to 6 Gbps with SATA III or SAS drives and RAID capability, but consider the transfer rate of the motherboard’s bus when you’re determining transfer speed.

6.7.2 Serial Advanced Technology Attachment

SATA is a computer interface and communication protocol introduced in 2003. Its specifications are currently developed by the independent, nonprofit Serial ATA International Organization led by multiple industry partners, including dominant computing systems and storage manufacturers. It is used primarily to provide connectivity to mass-storage devices. SATA replaces the older parallel ATA (PATA) technology that was characterized by lower data transfer bandwidths, bulky ribbon cables frequently obstructing air flow in the node's case, and lack of proper support for hot-swapping of I/O devices. SATA interfaces may be found on most modern internal (i.e., housed inside the computer enclosure and therefore nonportable) HDDs, SSDs, and optical drives (CD-ROM, DVD-ROM, BD-ROM and their data-writer equivalents).

SATA supports only point-to-point topology between storage devices and controllers or port multipliers. SATA data connectors, shown in Fig. 6.16, contain only 7 pins compared to 40 mandated by PATA: one pair of wires for data transmission, a second pair of wires for data reception, and three ground connections. Data transmission is performed over high-speed serial links that use similar technology to PCIe and share many of the same quality characteristics with it. Serial links also take advantage of matched impedance cables, guaranteeing signal integrity over distances of at least 1 m. The power connectors utilize a 15-pin arrangement that provides ground reference and the 3.3, 5, and 12 V supply voltages needed by most of the attached devices to operate, and may also control staggered spin-up functionality. The latter is particularly useful in storage nodes populated with potentially dozens of disk drives, as enabling all of them at once would put a considerable strain on power supply during the power-up cycle, possibly reducing its useful lifetime. Both types of connectors use a two-phase mating sequence to ensure that the ground connection is made first and eliminate the possibility of unpredictable floating potentials during drive removal or insertion when the system is powered up. Most of the computer motherboards manufactured today support multiple SATA data ports (typically two to eight), while common power supplies provide multiple SATA-compatible hookups.

The first revision of SATA specifications supported a 1.5 Gbps signaling rate, resulting in a maximum peak data transfer rate of 150 MB/s. With the increases in HDD media speeds and the introduction of solid-state storage, this proved to be a serious performance bottleneck, and the next revisions, SATA 2.0 and 3.0, increased the raw signal rate to 3 and 6 Gbps, respectively. Modern chipsets are capable of detecting device speeds through autonegotiation and are backwards compatible with older drives. Early SATA 2.0 implementations, however, may require that the device is explicitly configured to the correct interface speed by setting a jumper on configuration pins and in some cases also by forcing proper basic input/output system settings. The newer SATA revisions also support native command queueing (NCQ), which may drastically improve the performance of I/O-intensive multitasking workloads by reordering the requests at physical block level, resulting in an overall shorter travel distance for the disk head. Other extensions included introduction of isochronous quality of service for periodically scheduled data accesses, host-side support for NCQ processing, and better power management. The specifications have been twice revised since (version 3.1 in 2011 and 3.2 in 2013), and defined additional interfaces, capabilities, and power management functions:

mSATA interface for mobile devices

M.2 small form factor standard

microSSD standard for connectorless single-chip embedded storage

“zero-power” state for idling optical drives

TRIM command for SSDs that optimizes allocation of no longer used blocks on the device

universal storage module for cable-free docking of portable storage modules

required link power management, DevSleep, and transitional energy reporting for additional power savings

rebuild assist that speeds up data reconstruction in redundant arrays of independent disks

performance optimizations for solid-state hybrid drives

signaling speed increase to 16 Gbps with a corresponding peak data rate of nearly 2 GB/s.

Besides the originally defined SATA data ports for internal I/O devices, several other form factors specified by the standard are already in widespread use or gaining popularity. The external SATA (eSATA) connector shown in Fig. 6.17 has been developed to provide connectivity to external storage devices. It features more robust connector and permits longer cables (up to 2 m) thanks to changes in required signal voltage levels. It is also shielded to reduce EMI emissions. eSATAp, or powered SATA, attempts to solve one of main shortcoming of eSATA, namely the necessity to provide a separate power source (and therefore an additional cable) to the external device. While not fully standardized yet, it aims to provide 5 and 12 V supply voltages as well as SATA and USB 2.0 data lines.

Mini-SATA (mSATA) and its next revision, M.2 interfaces (Fig. 6.17B), are used where preservation of small form factor is important. They find applications in settop boxes and ultrathin laptops, but typically require a properly designed system board that is equipped with the correct connector and allows sufficient installation space.

A companion specification to SATA is the Advanced Host Controller Interface (AHCI) developed by Intel (currently at revision 1.3.1). It describes an implementation-independent, register-level interface between the host controller hardware and system software. The specification allows system programmers to support correctly additional hardware features such as NCQ and hot-swapping of I/O devices. AHCI is supported by default by many popular operating systems, such as Windows, Mac OS, and Linux.

SATA

SATA is an acronym for Serial Advanced Technology Attachment, and is the next generation that will probably replace ATA. It provides high data transfer rates between the motherboard and storage device, and uses thinner cables that can be used to hot-swap devices (plug in or unplug the devices while they're still operating). The ability to hot-swap devices has made SATA a possible successor to USB connections used with such things as external hard disks, which can be plugged into the computer to provide large removable storage or data.

Specialized Hardware

The Image MASSter Solo series hard drive duplicators generally support serial advanced technology attachment, IDE, Universal Serial Bus (USB), external serial advanced technology attachment, universal serial advanced technology attachment, serial-attached SCSI hard drives and flash memory devices. They can hash the disc images besides providing write-blocking to ensure the integrity of the copies. The imaging process can be either disc-to-disc or disc-to-file.

The Digital Intelligence Forensic Duplicator units have the same properties as the Image MASSter Solo series. But, they provide access to different hard drive formats through their protocol modules.

Hard disk connectivity standards (SATA)

The type of connection between the hard drive and the system (motherboard and CPU) is defined by one of a few standards.

The most popular up until 2010 was the Enhanced Integrated Drive Electronics drives (EIDE), which was also known as Advanced Technology Attachment (ATA). Some people called it Parallel ATA (PATA), because it had multiple parallel cables connecting the hard disk drive with the computer motherboard. This is now obsolete technology, giving way to the Serial ATA (SATA) standard. Serial offers several advantages over the PATA: reduced cable size and cost (seven conductors instead of 40), native hot swapping, faster data transfer through higher signalling rates, and more efficient data transfer. The SATA bus interface connects not only the host bus adapters to hard disk drives, but also to optical drives as well. Physically, the cables in SATA are the largest change. The data is carried by a light, flexible seven-conductor wire with 8 mm wide wafer connectors on each end. It can be anywhere up to 1 meter long. Compared to the short (45 cm), ungainly 40 or 80 conductor ribbon cables of Parallel ATA, this is a great relief to system builders. In addition, airflow and, therefore, cooling in equipment is improved due to smaller cables. The concept of a master-slave relationship between devices has been dropped. SATA has only one device per cable. The connectors are keyed so that it should no longer be possible to install cable connectors upside down, which often is a problem with PATA types.

The other popular standard of communicating with hard disk in the past was the Small Computer System Interface (SCSI). This has also become obsolete technology when using PATA drives as part of the SCSI.

So the current and most popular standard of connecting computer motherboard to hard disk(s) is the Serial ATA (SATA). The SATA drives dominate the PC industry today, and this is the case with the DVRs as well.

SATA host adapters and devices communicate via a high-speed serial cable over two pairs of conductors. In contrast, PATA used 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-set as legacy ATA devices. SATA industry compatibility specifications originate from The Serial ATA International Organization (SATA-IO). The SATA-IO group corroboratively creates, reviews, ratifies, and publishes the interoperability specifications and test cases.

There are a number of SATA standard revisions dealing with data transfer speed:

−

SATA v.1.0, speed up to 150 MB/s (1.5 Gb/s)

SATA v.2.0, speed up to 300 MB/s (3 Gb/s)

SATA v.3.0, speed up to 600 MB/s (6 Gb/s)

SATA v.1.0 was released in 2003. First-generation SATA interfaces, now known as SATA 1.5 Gb/s, communicate at a rate of 1.5 Gb/s, and do not support Native Command Queuing (NCQ). Due to some encoding overheads, the SATA v.1.0 has an actual transfer rate of 1.2 Gb/s (150 MB/s). The theoretical burst throughput of SATA 1.5 Gb/s is similar to that of PATA/133, but newer SATA devices offer enhancements such as NCQ, which improve performance in a multitasking environment. During the initial period after SATA 1.5 Gb/s finalization, adapter and drive manufacturers used a “bridge chip” to convert existing PATA designs for use with the SATA interface. Bridged drives have a SATA connector, may include either or both kinds of power connectors, and, in general, perform identically to their PATA equivalents. Most lack support for some SATA-specific features such as NCQ. Native SATA products quickly eclipsed bridged products with the introduction of the second generation of SATA drives. As of April 2010 the fastest 10,000 RPM SATA mechanical hard disk drives could transfer data at maximum (not average) rates of up to 157 MB/s, which is beyond the capabilities of the older PATA/133 specification and also exceeds a SATA 1.5 Gb/s link.

The second generation SATA v.2.0 interfaces run with a native transfer rate of 3.0 Gb/s, and the maximum un-coded transfer rate is 2.4 Gb/s (300 MB/s). The theoretical burst throughput of SATA 3.0 Gb/s is double that of SATA revision 1.0.

All SATA data cables meeting the SATA spec are rated for 3.0 Gb/s and handle current mechanical drives without any loss of sustained and burst data transfer performance. However, highperformance flash drives can exceed the SATA 3 Gb/s transfer rate, which was addressed with the next, SATA 6 Gb/s, interoperability standard. SATA 3 Gb/s is backward compatible with SATA 1.5 Gb/s.

The SATA v.3.0 was proposed in 2008, and deals with speeds of up to 6 Gb/s. In actual fact, after the encoding overheads, achieves maximum un-coded transfer rate of 4.8 Gb/s, which is equivalent to 600 MB/s. The theoretical burst throughput of SATA 6.0 Gbit/s is double that of SATA revision 2.0. There were some minor improvements on the previous SATA standards, such as improved power management capabilities, that are aimed at improving quality of service for video streaming and high- priority interrupts. In addition, the standard continues to support distances up to one meter. SATA v.3.0 is backward compatible with SATA v.2.0.

The SATA hard disks require a different power connector as part of the standard. Fifteen pins are used to supply three different voltages if necessary − 3.3 V, 5 V, and 12 V. The same physical connections are used on 3.5” and 2.5” (notebook) hard disks.

In 2004, there was a proposal for an external SATA, called eSATA. This was a variant of SATA meant for external connectivity. It uses a more robust connector, longer shielded cables (up to 2 m), and stricter (but backward-compatible) electrical standards. The protocol and logical signaling (link/transport layers and above) are identical to internal SATA.

The eSATA connector is mechanically different to prevent unshielded internal cables from being used externally. The eSATA connector discards the “L"-shaped key and changes the position and size of the guides. The eSATA insertion depth is deeper: 6.6 mm instead of 5 mm. The contact positions are also changed. The eSATA cable has an extra shield to reduce EMI to FCC and CE requirements. Internal cables do not need the extra shield to satisfy EMI requirements because they are inside a shielded case. The eSATA connector uses metal springs for shield contact and mechanical retention. The eSATA connector has a design-life of 5,000 connections, the ordinary SATA connector is only specified for 50.

Multiple SATA drives can be connected in a serial connection, which is called Serial Attached SCSI standard, or short SAS. The SAS is a point-to-point serial protocol that moves data to and from computer storage devices such as hard drives and tape drives. SAS replaces the older Parallel SCSI bus technology that first appeared in the mid-1980s. SAS, like its predecessor, uses the standard SCSI command set. SAS offers backward compatibility with second-generation SATA drives. SATA 3 Gb/s drives may be connected to SAS backplanes, but SAS drives cannot connect to SATA backplanes. The SAS has no termination issues, like the Parallel SCSI.

The maximum number of drives that SAS allows to be connected is 65,535 through the use of expanders, while Parallel SCSI has a limit of 8 or 16 devices on a single channel. SAS allows a higher transfer speed (3 or 6 Gb/s) than most parallel SCSI standards. SAS achieves these speeds on each initiator-target connection, hence getting higher throughput, whereas parallel SCSI shares the speed across the entire multidrop bus.

Discrete Device Expansion

You are not required to use a Platform Controller Hub. Given that the Intel Atom SOC provides standard PCIe interfaces, you can add almost any PCIe discrete device to the platform. For example, a SATA controller could be added with a Silicon Image SiI3132 SATALink PCI Express to a 2-Port Serial ATA II Host Controller. The devices can be soldered down on the platform or added as an add-in card through standard interfaces such as Mini PCI or PCI connectors. In fact, adding a PCIe-based module is the most typical mechanism for adding wireless capability to the platform. The development of a wireless module requires a specialized wireless skill set that may not be the core competency of the team developing the embedded system. The purchase of a wireless module significantly eases and reduces the risks of adding a wireless capability to an embedded platform.

16.3.3 Interface

Yet another way to classify disk drives is by the type of interface the drive provides. Current choices of interface are Fiber Channel (FC), parallel SCSI (Small Computer System Interface), parallel ATA (Advanced Technology Attachment), and the emerging serial ATA (SATA) and serial attached SCSI (SAS). A more detailed discussion of interface can be found in Chapter 20. Server class drives are available in either FC or SCSI interface. Desktop, mobile, and CE drives invariably come with an ATA interface, either the original parallel version or the newer serial flavor. Server class drives are more than twice as expensive as desktop drives. This association with interface leads some people to mistakenly think that SCSI drives are expensive because of the SCSI interface, when it is mostly the more costly technologies that go into a server class drive for achieving higher reliability and performance that makes it more expensive. As mentioned before, some storage systems are starting to use ATA desktop drives in certain applications to achieve a lower system cost.

The above various ways of classifying disk drives are summarized in Table 16.1. This is only a snapshot of 2007. A few years from now, the composition of this table may look different. Note that both SCSI and ATA can be either parallel or serial.

TABLE 16.1. Classifications of disk drives by form factors, by applications, and by interfaces

ImageMASSter 6007SAS

ImageMASSter 6007SAS is a powerful tool for creating images of data from suspect machines, and is a useful part of any forensic lab. It is developed by ICS, and is available from www.icsforensic.com. It duplicates IDE, SAS, SATA, and IDE hard drives, and can migrate server data from SCSI to SAS/SATA. ImageMASSter can also acquire data from multiple hard disks, and store multiple images on one hard drive. It is the only duplication system on the market that supports SAS (Serial Attach SCSI) hard drives, and can copy multiple drives simultaneously at high speeds. It also includes a 1 GB network connection that can then be used to transfer files to and from a network drive. To acquire and analyze data, the system provides a Windows XP-based interface that allows you to copy data from Windows, Macintosh, and UNIX file systems.

Install Devices

Installing hardware devices and drivers is much simpler in Windows 7 than in previous versions of Windows. There are several different types of hardware devices that may be installed on Windows 7 computers:

Internal Drives – hard drives, CD drives, DVD drives, Blu-Ray drives, floppy drives, Zip drives, and any other internal drive that is released can be installed on Windows 7. These devices generally include a data cable (Integrated Drive Electronics [IDE], Serial Advanced Technology Attachment [SATA]) that attaches to the motherboard and a power cable that attaches to the power supply.

Internal Cards – Adapters or expansion cards that are plugged into the desktops motherboard's expansion slots (Peripheral Component Interconnect Express [PCIe], Peripheral Component Interconnect [PCI], Accelerated Graphics Port [AGP]) including video cards, Redundant Array of Inexpensive Disks (RAID), and SATA controllers. Expansion cards for laptops are also considered internal cards. Generally, these cards are used to connect another device through a cable.

External Devices – Any external device that connects to the computer through the available ports including universal serial bus (USB), IEEE-1394 (FireWire), Line Printer Terminal (LPT), Computer Object Model (COM), and so on. These ports can be connected to printers, scanners, external hard drives, media devices, and so on through the appropriate cable.

Memory – Memory may be added to the computer's motherboard to expand the amount of memory the computer has access to.

Windows 7 automatically detects any hardware recently installed and attempts to automatically install the driver. Additionally, after Windows 7 Setup completes, if some drivers were not installed by default, Windows 7 will attempt to find the device and respective driver. This is possible through Windows Update. This section will cover basic methods of installing hardware devices including internal and external devices, printers, wireless devices, and so on.