Got any older?

Interesting article about the "oldest working Seagate drive in the UK". When we talk about storage here, eventually someone says "storage is getting cheaper". If you ever needed concrete proof, this is it!

Our first local 'dead' hard disk acquisition

We've imaged lots of removable media over the past year (~ 400, according to Victoria's stats), and I've also done a  fair amount of forensic imaging of material on-site with donors (live acquisition) . One aspect of our 'forensic' armoury that has not been subject to so much testing is the imaging of whole hard disks at BEAM. So-called 'dead' acquisitions.

In the past few months two new accessions have presented us with an additional four hard disks. This is excellent news, as I have finally had the chance to use our forensic computer's Ultrabay (write-blocking device) to image a real 'collection hard disk'. Everything went smoothly. So far so good.

Media Recognition - Hard Disk Drive part 3

Serial Attached SCSI (SAS) Interface

Type:	Magnetic storage media
Introduced:	2004
Active:	Yes [2010]
Cessation:	-
Capacity:	Varies, but majority do not exceed 300GB
Compatibility:	Compatible with all operating systems, though drives with a capacity of 137GB or more are only compatible with Windows 98 onwards and Mac OS 10.2 onwards. Not found on 8” or 5.25” drives.
Users:	Servers and high-end computers
File Systems:	FAT, NTFS, HFS/+, ext
Common manufacturers:	Western Digital, Seagate, Toshiba, Hitachi, Samsung

Recognition

SAS was born out of SCSI developments and entered the market in 2004. One feature making it preferable to SCSI is its higher transfer rate. Its fast speeds and high level performance make it suitable for high-end personal computer hard drives and servers. The first version was slower than the latest version of SCSI having a data transfer rate of 300 MB/s. However, in 2009 this rate increased to 600 MB/s and it is expected to reach 1200 MB/s by 2012. SAS uses point-to-point topology to connect the interface and can support multiple devices (up to 200), making it popular with servers. For the same reasons SAS hard disk drives are relatively expensive therefore they are not as common on standard personal computers as the more general purpose SATA interface.

The SAS connector is a 29-position connector. It is much smaller than its predecessor, SCSI, so as to be used on 2.5” drives. SAS connectors look similar to SATA connectors. The difference is that with the SATA interface the data and power connectors lie next to each other, but are separate, whereas with SAS the two form one connector, with a piece of plastic used to keep them distinct. This similarity is deliberate so that SAS connectors are compatible with SATA drives, but not the other way around.

External Hard Disk Drives

Early Apple Macintosh computers used external SCSI hard disk drives, despite internal hard disk drives being the standard for other PCs. More recently external hard drives are primarily used as additional storage devices.

Although the early Apple external drives were only compatible with Mac OS, later drives have been manufactured to support all modern operating systems. However, they cannot support any Windows OS preceding Windows 2000, Mac OS before version 8.5.1 or the Linux OS with a kernel earlier than version 2.4 unless updates are installed.

The hard disk in an external hard disk drive is no different to that in an internal drive, though an external drive is encased in plastic and the only visible part is the connector. This can either be a SCSI, eSATA, USB or FireWire connector.

FireWire (IEEE 1394): First released in 1995 this was originally developed as a replacement for the SCSI connector and many computers since 2003 have a built-in FireWire port, particularly Apple machines. FireWire has a higher transfer rate than USB and the latest version, FireWire 3200 has a rate of 393 MB/s, which also exceeds that of eSATA, although this rate varies with Windows OS. However it is more expensive than USB, hence it has never superseded USB’s popularity. It is compatible with Windows OS from Windows XP onwards, though issues with Vista have been raised. It is also compatible with Linux OS and Mac OS from version 8.6 onwards. The FireWire cables carry power and data on a single cable, therefore only one is needed for a device.

There have been several versions of FireWire each using different connectors. Here is a brief table setting this out:

Version	Cable Used	Date Introduced
FireWire 400 (IEEE 1394)	6-circuit	1995
FireWire 400 (IEEE 1394a)	4-circuit	2000
FireWire 800 (IEEE 1394b)	9-circuit	2002
FireWire S3200	9-circuit	2007

It is most common to find 6-cicuit connectors on desktop computers and 4-cicuit connectors on laptops. However, in 2000 amendments were made and the 4-cicuit connector was standardised resulting in more of these connectors being found on desktop computers.

FireWire 800 and 3200 are backwards compatible with these ports, but are manufactured with a 9-cicuit connector. Adaptors are available so that 9-circuit cables can be used with 4- and 6-circuit connectors on computers.

USB (Universal Serial Bus): USB was introduced in 1996 and has since become the dominant means to connect computer peripherals to the host controller. The original USB 1.0 has a transfer rate of 12 Mbits/s, which was increased to 60 MB/s (480 Mbits/s) by USB 2.0. This was released in 2000 and standardised in 2001. Like FireWire, USB connectors carry power as well as data, therefore do not require additional power cables.

There are several different USB cables available for different uses. The most common type found on computers is the A plug and port. A second type is similar in size and is usually found on extension cables. Mini plugs are also available for use with small devices such as cameras. The other sort is squarer and about half the width of the A plug. This is known as a B plug and is used on devices that use removable cables such as printers. Having two types of connector (A and B) prevents users accidentally creating an electrical loop.

eSATA: This is SATA’s own external connector introduced in 2004 with a transfer rate of 131 MB/s. Despite having a much larger data transfer rate, few computers have eSATA ports, favouring instead USB and FireWire.

Media Recognition - Hard Disk Drives part 2

AT Attachment (ATA) Interface

Type:	Magnetic disk storage
Introduced:	1986
Active:	Only on existing computers
Cessation:	Almost completely superseded by SATA by 2007
Capacity:	750 GB
Compatibility:	Compatible with all operating systems, though drives with a capacity of 137GB or more are only compatible with Windows 98 onwards and Mac OS 10.2 onwards.
Users:	Desktop and laptop computers, particularly low-end ones. The primary interface used by IBM and adopted by Apple in 1994.
File Systems:	FAT, NTFS, HFS/+, CP/M, ext, MFS
Common manufacturers:	Present: Western Digital, Seagate, Toshiba, Hitachi, Samsung Past: IMB, Apple, Sony, Hewell-Packard, Maxtor

Recognition

ATA, designed in 1986 was an evolved form of Western Digital’s original Integrated Drive Electronics (IDE). It was used for desktop and laptop computers. After the development of SATA in 2003 ATA became retroactively known as Parallel ATA (PATA).

Here is an example of an ATA interface. It is identified as ATA because of the rectangular 40-pin connector socket used. The second image shows the male connector.

The first ATA hard disk drive was used in the Compaq Deskpro 386. It had a transfer rate of 16 MB/s and a capacity of 128 GB. Later versions had larger transfer rates, though none exceeded 80 MB/s until 2005. Before the advent of SATA, ATA hard disk drives were popular with IBM PCs due to their low cost. ATA drives are also found on post-1994 low-end Apple Microsystems, the first being the Apple Quadra 630. In 1997 Apple also adopted ATA for their high-end machines starting with the Apple Powerbook G3. The ATA connector has a relatively short cable so ATA hard disk drives are commonly inbuilt.

Serial ATA (SATA) Interface

Type:	Magnetic disk storage
Introduced:	2003
Active:	Yes [2010]
Cessation:	-
Capacity:	Up to 2TB [2010]
Compatibility:	Compatible with at least one version of all major operating systems: supports versions of Windows after XP. Also, drives with a capacity of 137GB or more are only compatible with Windows 98 onwards and Mac OS 10.2 onwards. Unlikely to be found on 8” or 5.25” drives.
Users:	Servers, desktop and laptop computers. Adopted by IBM and Apple to replace ATA.
File Systems:	FAT, NTFS, HFS/+, ext
Common manufacturers:	Present [2010]: Western Digital, Seagate, Toshiba, Hitachi, Samsung Past: Maxtor

Recognition

SATA was introduced in 2003 as a faster version of ATA and is used with desktops, laptops and servers. It was intended to replace ATA, and had almost completely done so by 2007. SATA uses AHCI (Advanced Host Controller Interface) and if a computer does not have it SATA runs in ATA emulation mode. This applies to Windows OS up to Windows XP, though Windows Vista and later versions support AHCI. Linux with a kernel version 2.16.19 onwards will support AHCI as will Solaris operating system.

The image below shows an example of a SATA interfaced hard disk. The manufacturer’s details are clearly displayed. This type of interface uses a different connector, which is more clearly visible in the second image.

The SATA interface uses a 7-pin connector and socket, as seen in the above image. SATA differs from its predecessors in that it has the option of two power sockets. There is the standard Molex power socket on the right, but SATA drives also have their own power socket. This is a 15-pin connector situated next to the data socket. The image below shows the reverse side of the hard disk drive. The data socket is on the left and the power connector is on the right.

The images below show the two male connectors, with the data connector first then the power connector.

Initially SATA had a transfer rate of 131 MB/s and the SATA revision 2.0 increased this to 300 MB/s. SATA is still currently being developed and the latest version released in 2009 has a transfer rate of 600 MB/s. External SATA hard disk drives often include their own eSATA connector. More information about this will be in the next post.

Small Computer Scientific Interface (SCSI) Interface

Type:	Magnetic storage media
Introduced:	1981 (under the name SASI)
Active:	Only on existing computers
Cessation:	Early twenty-first century
Capacity:	2 TB
Compatibility:	Compatible with all operating systems, though drives with a capacity of 137GB or more are only compatible with Windows 98 onwards and Mac OS 10.2 onwards.
Users:	Servers and primarily high-end computers. Used on all microcomputers until ATA established. Used by Apple for low-end machines until 1994 and high-end machines until 1999.
File Systems:	FAT, NTFS, HFS/+, CP/M, ext, MFS
Common manufacturers:	Present: Western Digital, Seagate, Toshiba, Hitachi, Samsung Past: IMB, Apple, Sony, Hewell-Packard, Maxtor

Recognition

SCSI was introduced in 1981 under the name SASI (Shugart Associates System Interface). It was used with various operating systems including Microsoft Windows, Mac OS, Unix and Linux. However, as ATA gained popularity SCSI became associated more with high-end machines and servers. Even then SCSI began to lose popularity in the 1990s and was abandoned by Apple Macintosh in 1999. In the last decade provision for SCSI on motherboards has been largely discontinued with manufacturers preferring SATA and SAS.

The SCSI interface uses either a 68 or 80-pin connector (68-pin is more common) and a Molex power connector. The images below show the female and male 68-pin socket and connector.

The first SCSI interface had a transfer rate of 3.5 MB/s which soon increased to 5 MB/S. The rate increased in 1994, 1997 and again in 2003 to reach 320 MB/s.