SAS: Reliable from the Start

Author: Harry Mason
LSI Logic

An often over-looked aspect of system reliability is software quality. Software quality improves as the software is used in real world applications and as it undergoes revisions, until the failure rates are quite low. In short, software run time is a necessary requirement to deliver highly reliable enterprise-class storage solutions.

Serial Attached SCSI (SAS) was architected from the beginning to leverage more than two decades of legacy SCSI software. As such, the middleware applications that have supported SCSI over this lengthy period of time can be reused without sacrificing any enterprise-proven functionality.

Plugfests Bring Confidence
The SCSI Trade Association (STA) has established a series of plugfests designed to instill confidence in the SAS interface as it enters the market and as it evolves well beyond the capabilities that SCSI has provided to the enterprise over the past 20 years.

STA plugfests have focused on three primary areas to ensure rapid market adoption for this emerging interface: interoperability with other SAS components, protocol compatibility with existing Serial ATA (SATA) products, and the ability to run legacy SCSI software.

SCSI Middleware Is An Advantage
With key industry leaders cooperating on these plugfest initiatives, along with the added advantage of the wealth of existing time-tested SCSI middleware, SAS is poised to make an immediate mark on the industry. SAS will not have to suffer through the lengthy growing pains that other interfaces have experienced. Leveraging the wealth of installed SCSI middleware will deliver immediate benefits to the industry in terms of proven reliability.




SAS market adoption is clearly aided by the ready availability of infrastructure components, the breath of industry commitment, and the abundance of legacy middleware. With SAS plugfests exposing any implementation inconsistencies between vendors, the market is confident that SAS will be rapidly deployed into the enterprise, while preserving the proven reliability of legacy SCSI implementations.

Highly Reliable SAS Systems
With two successful plugfests behind it and a third scheduled for early November, the SAS community is intent on concluding 2004 with production-capable, enterprise class, highly reliable systems that preserve enterprise trusted SCSI middleware. In short, SAS will be reliable from Day One.

As systems begin to ship in 2005, SAS vendors will continue to expand the capabilities of these enterprise-capable systems far beyond those of traditional SCSI systems. The additional reliability features that have been added to the interface promise to grow SAS’s usage within the enterprise.

NOTE: a graphic representation of SCSI middleware that sits between the application software and the operating system device driver software, may be added to the article.

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