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Storage: the need to be flexible

Storage: the need to be flexible

Not unlike the world of gymnastics, top performance and flexibility in the world of storage is a big bonus. And with enterprise storage requirements escalating and becoming more complex, serial attached SCSI (SAS), is promising to offer larger capacity, greater density, security, scalability and accessibility.

Let's take a peek under the covers. SAS is an enterprise-class, serial interface for hard-disk drives that is physically compatible with serial advanced technology attachment (SATA), but provides added features and legacy Small Computer System Interface (SCSI) data protocol compatibility, Gartner's storage research vice-president, Phillip Sargeant, said.

Targeted at enterprise storage OEMs, VARs and end-users who want solutions that address current and future storage requirements, the technology will align serial ATA (SATA) technologies to better serve storage users. It aims to offer users larger capacity at a lower cost.

According to industry proponents, SAS will be more attractive to the industry because of its compatibility with SATA, as both types of disk drives can be installed and controlled in the same SAS system. The technology was developed to address anticipated I/O and direct attach storage requirements that traditional SCSI will not be able to meet, according to the SCSI Trade Association.

Since its inception in 2001, there had been many milestones in the development of SAS, Adaptec director of strategic marketing, Linus Wong, said.

Wong, a member of the SCSI Trade Association said Technical Committee T10, under the direction of the International Committee for Information Technology Standards (INCITIS), began work on developing the SAS standard in 2002, culminating in the release of version 1.0 at the end of 2003.

"The primary market driver is the need to replace the parallel SCSI interface," Wong said. "SCSI is the dominant storage interface in the volume server market. For more than 20 years, SCSI has continually evolved to provide greater levels of bandwidth and performance. However, each of these transitions becomes more difficult and expensive.

"Unlike today's parallel SCSI architecture, SAS is a serial implementation of the SCSI protocol. SAS provides greater scalability, reliability and performance, and offers a future roadmap to another 20 years of SAS generations."

Business benefits

In a nutshell, the main benefits of SAS over parallel SCSI include faster signalling and improved addressability, according to Gartner's Sargeant. "The improved addressability is achieved incrementally by using SAS expanders that allow connectivity to 128 physical links from host controllers, HDDs or other SAS expanders," Sargeant said.

Other top benefits include smaller connectors: this allows dual-ported connections on 3.5-inch and smaller drives.

"Because SATA shares the same connector form factor with SATA, this makes upgradeability from SATA to SAS straightforward, at least in theory," he said.

But let's not get too excited, Sargeant said.

"SAS is not going to take over the world. It will move aggressively into mainstream production during 2006, but we expect its market penetration to be between 5-20 per cent of the target market," he said.

At any rate, this type of technology was providing end-users with benefits such as lower costs and additional functionality, EMC director of marketing, Clive Gold, said.

"Higher performance and density of these devices will help EMC provide more cost-effective systems in the lower-end of the market," Gold said. "As the systems perform better at a lower total cost, they address a wider market.

With a view on end-user and reseller benefits, Sun Microsystems was also readying its SAS strategy and would be rolling out servers and storage incorporating SAS technology, client solutions storage and data management practice manager, Dan Kieran, said.

"Over the next six months, we will be releasing a variety of products which will all have SAS inside," he said.

SAS was a much more robust solution with the kind of performance, reliability and scalability demanded by the enterprise, Kieran said.

Western Digital was also gearing up for mainstream adoption of SAS technology, director, enterprise product marketing, Hubbert Smith, said.

The technology offered a nice mix of high performance and high capacity - often IT managers had to choose between these two features, Smith said.

So what lies ahead? SAS will be generally used in data centre environments and upper end storage arrays, whereas SATA would replace the parallel form of ATA (PATA) in most desktops and notebooks, Gartner's Sargeant said.

While SATA had a 10-year road map consisting of three product generations, and would become a dominant physical storage interfacing on computing platforms, SAS was considered a more appropriate technology for mission-critical applications, Gartner's Sargeant said.

"These environments require higher data rates, distributed configurations [for example, storage area networks], or both, especially in cases where SCSI and FC are already in place," Sargeant said.

Indeed, the two technologies will talk to each other. The SCSI Trade Association was collaborating with the SATA group to develop specifications that would ensure compatibility between systems based on these interconnect technologies, he said.

The SCSI Trade Association said some SAS components were available today globally, and complete SAS systems and servers were expected to ship this year.

The Association's Wong said IBM began shipping production SAS systems earlier this year, and SAS solutions were available from HP. "These early systems will lead to a full volume ramp for SAS in 2006," he said.

Locally, Adaptec would launch a full line of SAS controllers, RAID controllers and external enclosures before the end of the year, Adaptec's chief technology officer for components and RAID, Tom Treadway, said.

The SAS-sy reseller

So where can resellers find some market opportunities? Gartner's Sargeant said resellers could leverage the work that's being done in the SATA world since there's a lot of commonality between SAS and SATA.

McData country manager, Ken Cooper, agreed SAS and SATA technologies were expanding the potential market for storage resellers by enabling mid-tier customers to implement affordable networked storage solutions.

"At the high end, enterprise class customers continue to deploy Fibre Channel systems and disks due to high performance, reliability and well-established solutions for consolidation, backup, data replication and other storage applications," Cooper said.

"For mid-tier customers, SAS and SATA provide new opportunities to gain the benefits of shared storage at a lower entry cost, and with increasing reliability to safeguard their data assets."

Sun's' Kieran said SAS would expand the potential market for resellers, but the technology was still in its infancy.

"SAS may well facilitate the deployment of additional storage capacity in businesses, but it is unlikely any end user is going to buy more storage simply because of the connectivity offered," Kieran said.

For end-users, key benefits included enterprise class robustness, investment protection in compatible SCSI software and middleware, and the choice of direct-attach storage devices (SAS or SATA) in the same SAS system.

For resellers interested in doing a SAS implementation, there would be a host of components available from all of the major disk vendors, host adapter suppliers, storage suppliers, chipset manufacturers, and large computer makers, Wong said.

Essentially, SAS enabled smaller footprint products and offered customers flexibility in deploying the right storage for the right application, Wong said.

"Resellers will be able to leverage all of the capabilities of SAS to bring new storage solutions to their customers at new price points," he said.

SIX SAS BENEFITS
1) Leverages SCSI technologies. 2) Provides robust solutions and generational consistency. 3) Based on serial interface, the technology allows for increased device support and bandwidth scalability. 4) Reduces the overhead impact that challenges today's SCSI environments. 5) By utilising SATA development work on smaller cable connectors, it provides customers a downstream compatibility with desktop class ATA technologies. 6) Simplified routing enables a new generation of dense device such as small form factor hard drives,permitting storage solutions to scale externally. Source: SCSI Trade Association


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