Author: Mike Micheletti, Product Manager,
Lecroy Corporation
Serial Attached SCSI (SAS) is a storage interface developed to meet the needs of enterprise-class storage applications. Central to the SAS value proposition is the ability to scale storage systems beyond the limits of today's parallel SCSI using a switching technology called Expanders. Designed to provide fan-out architecture for SAS, expanders allow SAS initiators to connect up to 16,000 physical devices in a single domain.
Storage integrators are now busy validating multi-terabyte storage subsystems that include active backplanes containing multiple expanders with 64 or 128 disks in a single enclosure. The SAS architecture is designed to seamlessly scale performance as the number of targets increases. But, as with any new technology, integrators pushing the envelope with these external RAID configurations may encounter problems not seen in simple internal direct-attached storage (DAS) applications.
