What is Serial Attached SCSI (SAS)?

Serial Attached SCSI is a data transfer technology designed to move data to and from computer storage devices. It is a point-to-point serial protocol, rather than multidrop, that replaces the parallel SCSI bus technology that first appeared in the mid 1980s and has been in use in corporate data centers ever since. According to online resources, SCSI still claims to be slightly faster than SAS, however, that all depends on who you ask and the data we've seen is nearly a year old. SAS also promises to double it's current speed of 3.0 Gb/s to 6.0 Gb/s in 2009 so making the move to SAS by 2009 is a no-brainer.

The interface port of the latest generation of Serial Attached SCSI has changed dramatically. For many computer enthusiasts a "serial cable" is large 9-pin cable that has been around nearly as long as computers themselves. The new SAS signal cables are nearly identical to a SATA cable. In fact the pins are identical, but the SAS1-2 cables and ports have a special keyway to prevent a standard SATA signal cable from connecting to a SAS device or port. However, an SAS1-2 cable will connect directly to a SATA hard drive. And yes, the latest generation of SAS controllers will operate SATA devices. Goodbye SATA, nice knowing you... And if you were wondering, the power cables are identical to SATA power cables as well.

If you look closely at the keyways in the hard drives above, you can see that they are keyed differently. The top hard drive is an SATA ES.2 hard drive and the bottom one is a SAS hard drive. The SAS hard drive has a bridge between the power and signal ports.

Above is a photo of a SAS1-2 cable that came with my ASUS P5N64 WS Professional motherboard. As you can see the power and the signal cable are integrated. This cable will work with both SAS and SATA devices.

15K.6 Key Advantages

• Second-generation perpendicular recording delivers up to 450-GB capacity.
• Unprecedented performance with a 28 percent increase in sustained data rate, up to 164 MB/sec.
• Industry’s highest 3.5-inch drive reliability at 1.6-million-hours MTBF.
• Seagate proprietary PowerTrim™ technology provides a 61 percent improvement in watts/GB at idle.
• Advanced read/write technology delivers unrecoverable error rate of 1x10-16
• Available in FC or SAS interfaces

Best-Fit Applications

All mainstream enterprise applications, such as:

• Email
• Business processing
• Transaction processing
• Decision support
• Storage area networks
• Networked attached storage
• Internet and e-commerce

15K.6 Specifications

Product Manual (PDF)

Product Overview (PDF)

Data Sheet (PDF)

Page 1: Intro to SAS Page 2: SAS Details Page 2: 15K.6 Specs Page 3: Single Drive Tests Page 4: 15K.6 in RAID Page 5: ES.2 vs. 15K.6 Page 5: Conclusion