SATA overcomes PATA’s shortfalls
With its higher transfer rate and capacity, Serial ATA will replace traditional PATA technology in the hard disk drive market says Abhinav Singh
70 percent of the hard disk drives sold in India use PATA (Parallel Advanced Technology Attachment) technology. That said, SATA (Serial Attached Advanced Technology Attachment) is likely to supersede PATA in the next few years. Aimed at desktops and entry level servers, SATA is designed to overcome many of PATA’s limitations while maintaining a cost-efficient design that allows it to meet the requirements of traditional PATA markets. As was the case with PATA, SATA is being integrated into industry chipsets. Once these chipsets reach adequate volumes, it is expected that SATA will cost about the same as PATA does today at the system level. SATA will also effectively satisfy the storage interface needs of desktop and mobile PCs, as well as entry-level servers and networked storage solutions.
Higher transfer rates
Traditional PATA cannot scale to support any more speed doublings and it is nearing the end of the road when it comes to squeezing out more performance capacity. Sharad Srivastava, country manager, Seagate Singapore International Headquarters says, “The SATA roadmap is expected to support up to 10 years of storage evolution, based on historical trends.”
Hot pluggable disks
PATA disk drives are limited by their signal and power connectors to cable-attached applications. The Serial ATA connector, which can be blind-mated and hot-plugged, enables SATA disk drives to be used in both cable and backplane-attached applications (such as rack-servers). This capability is expected to accelerate the acceptance of SATA drives in entry-level enterprise market segments that do not require SCSI (Small Computer System Interface)-level features such as variable sector sizes, extended error reporting, 256-level command queuing, and out-of-order queue capabilities. Hafeez Khawaja, senior regional director, Middle East, Africa & South Asia, Western Digital says, “SATA supports hot-plugging, the ability to swap out a failed hard drive without having to power down the system or reboot. This capability contributes to both data availability and serviceability without any associated downtime, making it a critical feature for extending into enterprise applications.”
SATA drives let the industry move to lower voltages and pin counts for efficient integration in future chipsets and other integrated silicon components. The thinner, more flexible cable improves airflow within the system and facilitates the development of better thermal design and systems with smaller form factors. In addition, the new connector is more reliable, improving on PATA, which has a long history of problems with bent pins.
Set to be cost effective
SATA is designed to be a drop-in replacement for PATA for desktops and entry-level servers. The price differential between a SATA and PATA is just five percent at the desktop level. Srivastava says, “This is an age of low-cost PCs so SATA technology has avoided adding features that would require extra costs, features that would be necessary for an enterprise hard drive, enabling it to intelligently handle massive I/O and withstand enterprise workloads.”
Picking up steam
Many SATA drive vendors feel that the technology has gained unprecedented acceptance from the entire industry. 400 GB SATA drives are expected by end 2004. As chip makers, controller and motherboard vendors and hard drive manufacturers release products, markets that can take advantage of SATA’s new features will be the early adopters. System integrators will continue to work out when and how best to implement the new standard and to communicate to their customers how SATA will improve their solution’s ability to meet application needs. As higher volumes enable cost parity with PATA products, adoption will ramp up and SATA will replace PATA.
SERIAL ATA ................................................Parallel ATA
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Current spped/future 150MBps-300&600..........100MBps
Signal V level 400mV......................................Requires 5V tolerance
Cable integrity Smaller, thinner,one meter........Wide,lots of pins,18inches
Easy of use&integration - Snap in connectors...Many pins that can bend
Flexibility Better airflow...................................Airflow blockage
Reliability ATA command and CRC..................CRC for data only
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