Seagate ST3300657SS Enterprise-Optimized 6Gb/s SAS Rivals Fibre Channel Perfor - Page 3

Enterprise-Optimized 6Gb/s SAS Rivals Fibre Channel Performance and Scalability at Lower Cost 6Gb/s SAS: Performance, flexibility and value in affordable and easy-to-manage storage environments Feature Function Benefit 6-Gb/s transfer rate Enables enterprise-class performance at 2x the throughput of today's SAS/SATA environments Standardized expander zoning Provides common infrastructure with seamless scalability Expander self-discovery Provides common infrastructure with seamless scalability 10-M cable length Extends connectivity by 66 percent supporting networked storage expansion beyond a single rack Greater signal integrity with SSC Enables 6Gb/s SAS drives installed in close proximity to one another without compromising data integrity Cost-effective simplification Simplified connectivity with standardization on mini SAS connectors Investment protection Retains compatibility with earlier SAS/SATA hard drives and SCSI software/ middleware Management efficiencies Utilizes existing IT SCSI expertise Figure 2. Features and Benefits of 6Gb/s SAS specialized (and expensive) expertise not found in many IT departments. Hence, FC has typically been limited to enterprises with the needs (and deep pockets) to justify its use. Devices with 6-Gb/s transfer rates deliver greater performance, flexibility and value in traditional direct-attached applications such as internal server storage. But more importantly, 6Gb/s SAS storage solutions now offer an affordable, easyto-manage alternative to FC in network storage environments. Achieving this capability required several key enhancements to the SAS standard developed by the T10 Committee1. These new key enhancements are detailed in the following sections: Standardized Expander Zoning Standardized expander zoning provides common infrastructure with seamless scalability. While the SAS-1 specification theoretically enabled enormous addressability (up to 128 expanders, each supporting up to 128 SAS devices), in practice, even a few hundred storage devices or subsystems required some type of zoning scheme to assign storage domains when used with multiple hosts. This capability, known as expander zoning, was not formally defined in the SAS-1 standard. As such, such zoning could be implemented in a variety of vendor-specific, and frequently incompatible, ways that result in zoning incompatibilities that can lead to inaccessible storage and/or limit customers to single-vendor solutions. To eliminate such incompatibilities, standardized expander zoning is part of the SAS-2 specification and a required feature in all 6Gb/s SAS expanders. Furthermore, expanders can now support up to 256 devices. What's more, 6Gb/s SAS expanders support secure zones, similar to fibre channel SAN zones. Utilizing denial of service and device access control by zone technologies, networked storage can be grouped so that multiple hosts may talk to the expander, but see only a specified subset of the storage devices. This provides greater data security and makes storage easier to manage in the multi-drive network storage environments typical of enterprise data centers. 1 The T10 Committee (www.t10.org/) is part of the International Committee on Information Technology Standards (INCITS) and is accredited by, and operates under rules approved by the American National Standards Institute (ANSI). These rules are designed to ensure that voluntary standards are 3 developed by the consensus of industry groups such as SCSI Trade Association (SCSITA, www.scsita.org).