SCSI vs SATA
       It is a relatively common belief that SCSI, or serial attached SCSI (SAS) in its newest incarnation, is faster than SATA for any and all situations. While this may be true for server usage patterns, and may have been true at one point for desktop applications, it no longer applies.

MTBF
      This is a measurement of a hard drive’s reliability that is often quite misunderstood. The MTBF, or mean time between failures, is a length of time that is achieved by monitoring failure rates for a large number of drives. For example, if drive A has a 600,000-hour MTBF and drive B has a 1.2 million-hour MTBF, don’t assume that drive A will last 68 years and drive B will last 137 years, it just isn’t going to happen.

SATA I/O
      The term ‘SATA II’ is often used, incorrectly, to indicate that a drive has a 300MB/sec interface. The organisation that penned out the features of the newest SATA standard was named ‘SATA II’ which is where the confusion came from; the name is now changed to SATA-IO in an attempt to stop manufacturers from using incorrect terminology.

NCQ
      Native command queuing, or NCQ, is a feature that has been included in many consumer SATA drives in the last few years. Command queuing is a technology that was introduced in 1994 as TCQ (tagged command queuing) with the SCSI2 standard, so it’s by no means a new development. The technology allows for significant performance improvements when used in server environments by reordering commands sent to the drive, optimising them so that there is as little head movement as possible when servicing the commands.

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