Alternatives to ATA and SCSI

ATA and SCSI are the dominant hard disk interfaces today, but there are alternatives. One is the Universal Serial Bus (USB), which is a popular means of connecting external Zip drives, CD-R drives, and the like. USB 1 .x is very slow (1,5MB/s), and so isn't suitable for hard disks except for some low-performance functions. The newer USB 2.0 is fast enough to support hard disks (60MB/s), and may become important for this function in the future. Linux creates USB-to-SCSI interfaces for USB disk devices, so USB drives look like SCSI drives to Linux software.

Another alternative is IEEE-1394, aka Firewire. Like USB 2.0, IEEE-1394 is a fast interface (up to 100MB/S) and so is useful for hard disks as well as other disk-style devices. IEEE-1394 is becoming popular as a means of attaching external hard disks, and Linux provides an IEEE-1394-to-SCSI driver so that these devices look like SCSI devices. This support is still fairly new in the 2.4.x kernels, though.

USB 2.0, IEEE-1394, and more exotic variants such as Fibre Channel are all most important as means of connecting external drives. ATA is likely to dominate the internal drive market for desktop computers for the next few years, although ATA is likely to be extended. One ATA extension that's emerging is serial ATA, which uses serial cables rather than parallel cables.

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