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The relatively staid world of disk interconnects is suddenly heating up. ATA disks are transitioning to Serial ATA (SATA). SCSI disks are going to transition to Serial Attached SCSI (SAS). To make this even more interesting, the SAS technology enables a system to be built that accepts both SAS hard drives and SATA hard drives. This compatibility between SAS and SATA is a completely new paradigm that demands our attention.
Serial Technology Benefits
It has become increasingly difficult for SCSI and ATA to continue to increase performance with their existing parallel buses. The transition from parallel to serial technology is necessary if SCSI and ATA are to meet future requirements for performance and manageability. There are many benefits of transitioning SCSI and ATA to serial technology. Table 1 summarizes the features serial technology brings to SCSI and ATA, as well as the benefits of each.
Who Needs SAS/SATA Compatibility?
Who benefits from compatibility between SAS and SATA? Nearly everyone involved in building, selling and using servers and networked storage. Let's look at the different groups that benefit from this breakthrough in more detail.
Figure 1 illustrates how mainstream servers take advantage of this compatibility.
Today, many backplane manufacturers develop a backplane for SCSI drives and a separate backplane for ATA drives. SCSI and ATA require routing a large number of signals that lead to many layers in the backplane. The use of serial technologies reduces the number of layers in the backplane, resulting in a less expensive board. And, the emergence of SAS means that manufacturers need...