Seagate ST3146707LW SAS and SATA: Multiple Benefits of Unified Storage (334K, - Page 1

Technology Paper SAS and SATA: Multiple Benefits of Unified Storage Introduction Just as parallel lines never intersect, so too were the parallel storage interfaces of the last two decades destined to remain independent. When parallel SCSI and parallel ATA were conceived over 20 years ago, their roles in IT infrastructure were fundamentally distinct: servers needed the speed and reliability of SCSI storage, while economical ATA storage was adequate for desktop use. Given their disparate duties, compatibility between the two seemed unnecessary. However, over time it became increasingly clear that server storage embraced a broad variety of data, some of which didn't necessitate the superior performance and dependability of SCSI storage (and the higher cost per GB that such storage entailed). Deploying a separate, redundant parallel ATA infrastructure for such data was an inefficient and unwieldy workaround. Furthermore, the fundamental physical and electrical constraints of parallel storage buses had become increasingly problematic as faster throughput was sought, discouraging further development. By contrast, serial interfaces were growing by leaps and bounds thanks to recent breakthroughs in very large scale integration (VLSI) technology and high-speed serial transceivers. Simpler, faster and more robust, serial architecture was clearly the wave of the future. Change for the Better Thus when Serial ATA (SATA) arrived to supplant its parallel predecessor, the substantial gains it delivered in speed, scalability, data integrity and reliability were more than enough to ensure swift and enthusiastic adoption throughout the storage industry. Serial Attached SCSI (SAS) soon followed, and had it merely emulated SATA's transition from parallel to serial architecture, it would nevertheless have represented a significant advance in SCSI storage.