Storage vendors at this weeks Intel Developers Forum in San Jose, Calif., showcased the Serial ATA II feature set with demonstrations of performance-enhancing native command queuing and port multiplication. While on view in a number of booths, one demo likely passed under the radar of most attendees: a prototype SATA II external interface.
Now, the SATA II standard is still taking shape and some additions to the specification were released only recently. The set is broad and storage vendors will be able to pick and choose which features they will implement in a product, according to Knut Grimsrud, Intel Corp. senior staff systems architect and chair of the Serial ATA Working Group.
The Working Group, this week announced progress on a number of Serial ATA II features, such as the Digital 1.1 specification (a batch of management routines between devices and hosts); Port Multiplier 1.1, which lets users connect a single host to many SATA drives and determine each devices status; and the Port Selector 1.0 specification, which allows two different hosts to connect to a device, a necessary capability for fully-redundant servers and backup solutions.
The performance gains available from SATA IIs technologies were impressive. A number of developers showed a range of systems, from large and mid-size rack-mounted arrays to multiport host bus adapters. For example, Adaptec Inc. showed a range of SATA RAID systems as well as a prototype dual SATA and Serial SCSI controller.
There were a number of SATA II products shown in booths on the show floor. One had a SATA drive with native command queuing dueling an identical mechanism without the support. It was no contest: the drive with the technology averaged 335 I/Ops while its slower sibling ran at 160 I/Ops. Seagate made a splash announcing a drive with the technology. (For more information see Hard Disk Command Queuing Goes Native in Seagate Drive.)
In an Intel demo of the Port Multiplier specification, a small set of drives on a single SATA II channel outperformed two channels of Parallel ATA, which had more potential capacity. The SATA architecture, however, kept the drives busy and the bus filled. "SATA II is all about efficiency," Grimsrud said.
With the arrival of SATA several years ago, Ive mostly thought of SATA as an internal interface, even though it support a total cable length of a meter. This was the plan Grimsrud said, and for Version 1.0 of the specification, the group focused on simply providing a replacement for internal, parallel ATA, while at the same time trying to keep the costs down for storage vendors.
Seeing certainly helps believing. The performance available from such a small package was striking, all through a single, thin cable. This system was very portable, perhaps the size of several hard bound books or one big tome. That it was playing high-definition video made no difference (seriously), this could have been a backup. The combo of speed and convenience made me want to take one home. That no computer has an external SATA port is a minor issue; there will be.
"With Serial ATA II, we tried to do more," Grimsrud said, including the development of "additional goodies" such as a physical connector standard. The cable is wrapped around the usual connector, providing an extended cable, spring clips and beefed up shielding, which is completely absent from the current cable engineered for internal placement.
At the same time, we can only hope that the final version of the external interface are sturdy. A tech recently mentioned to me that he currently runs a dab of hot glue across the internal SATA connector when shipping a server across the country. Too many drives were being received unplugged after transit, creating a major blip in the tech support operation.
Some vendors have called SATA a disruptive element in the storage value chain. Whats most important to your storage purchase: price, performance, value or reliability?
Editor of eWEEK.coms Storage Topic Center, David Morgenstern is a longtime reporter of the storage industry as well as a veteran of the dotcom boom in the storage-rich fields of professional content creation and digital video.
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