Authors: Chris Hoffman, Senior Product Marketing Manager
Sam Sawyer, Director of Product Marketing Embedded Storage Products
Emulex Corporation
Introduction
Several years after its initial ratification, the Serial Attached SCSI (SAS) protocol has gained momentum and is now entering the advanced stages of replacing parallel SCSI for the purpose of connecting disk drives in server applications. The majority of drives now being used for these internal storage system applications are SAS interface drives.
Within external storage systems the story is different. Fibre Channel has been the dominant protocol for providing high performance back-end connectivity from the RAID controllers through the disk enclosures and ultimately, down to the disk drives. Now with the success and efficient high-volume production of SAS drives used as internal storage for servers, the general competitiveness and even long-term availability of Fibre Channel disk drives has become uncertain. In response, storage system suppliers are rethinking the design of their external storage systems to incorporate SAS as a back-end protocol with the goal of deploying SAS drives. Like Fibre Channel, a SAS infrastructure can support the attachment of SATA drives, providing both high-performance and low-cost storage alternatives.
This article explores three alternatives for connecting high capacity, low-cost disk drives into external storage system designs utilizing the SAS protocol.
