The next generation of Serial ATA (SATA)
But first, a quick history lesson on the term SATA II.
Recently, companies such as Infortrend Inc., LSI Logic Inc. and Addonics Technologies Inc. have announced their intentions to produce SATA II products. Disk makers, such as Western Digital and Samsung, have also started shipping SATA II disks. By the year's end, most SATA vendors will be offering SATA II products. However, a good percentage of them won't be using the term SATA II.
SATA I/O was the original supporter of SATA and began developing advanced SATA standards -- standards that were not intended to be named SATA II. Since these standards have sported that name for several years, confusion has set in throughout the industry.
SATA I/O discourages the use of the term SATA II. Unfortunately, there isn't a term appropriate enough to replace it. "Advanced SATA" has been commonly used by vendors and others to describe first-generation SATA drives with added features. As a result, "SATA II" is probably here to stay, despite its ambiguity.
SATA II is actually a bundle of features rather than a specification. SATA II drives, controllers and arrays may or may not have all the same features. When purchasing advanced SATA products, it is important to know what features you are getting instead of relying on the label "SATA II."
The most obvious distinction between SATA and SATA II is a higher level of speed. Almost everything labeled as SATA II or advanced SATA supports 3 gigabyte (GB) per second transfers, twice as fast as the previous version of SATA.
From a performance standpoint, most SATA II products SATA II allow intelligent command queuing, which rearranges up to 32 commands at a time in the controller's queue to provide higher throughput.
However, other features, such as port multipliers and the new connector design, aren't necessarily supported in all SATA II products. These features can be important advantages, depending on the desired configuration. Port multipliers, for example, allow several drives to be connected to a single USB or another external port. Enclosure management lets the system know which disk has failed in the enclosure. The new connectors, with positive click connections, make life easier for technicians installing drives, but they aren't a critical improvement for most operations.
There is relatively little difference in cost between the new and old SATA drives. Many new generation 3 GB per second drives have street prices between $100 and $150.
SATA still isn't a performance replacement for SCSI, but the combination of improved throughput and intelligent queuing gives it better performance than the older version of SATA in RAID arrays, while maintaining a significant cost advantage over SCSI RAID.
For more information:
About the author: Rick Cook has been writing about mass storage since the days when the term meant an 80 K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last 20 years, he has been a freelance writer specializing in storage and other computer issues.
This was first published in July 2005