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ATA: front-runner or Trojan Horse?

From STORAGE Magazine Vol 4 No 03 - June 2004

Roger Turner, Director Hardware Marketing, EMEA, Hitachi Data Systems warns that ATA is a classic case of horses for courses

Advanced Technology Attachment (ATA) storage disks and interfaces are being widely hailed and implemented as a low-cost storage solution for the enterprise. Many IT managers, especially those with burgeoning storage requirements and shrinking budgets, view ATA as the type of gift horse that should not be looked in the mouth, while others claim that ATA cannot keep up with the pace when the going gets tough. So, is ATA a front-runner or a dangerous gamble?

ATA certainly has a thoroughbred pedigree. It's been the cornerstone of PC chipset-to-storage communication for more than 15 years. In this time, its performance has evolved in tandem with processing power. The momentum behind ATA has seen it become the popular low-cost storage solution, morphing ATA far beyond its hard disk drive (HDD) heritage.

The latest generation of ATA is Serial ATA (SATA). Not surprisingly, SATA is widely tipped to make Parallel ATA (PATA) obsolete in the very near future. According to Gartner Dataquest, by the end of 2005, SATA will account for 75 percent of desktop and mobile HDD interfaces.

SATA certainly has the form to become a clear favourite. It uses considerably less energy, so the knock-on benefits for PC manufacturers include longer battery life (or the option to use cheaper batteries), the use of more economical low-power chips, and reduced heat generation. These benefits result in massive cost savings for PC manufacturers.

Beware the dark horse
Many organisations are being encouraged by over-enthusiastic storage salesman to adopt SATA as a cost-effective storage solution, with proven form, for enterprise environments. Understandably, when faced with the demand to make more information available online for longer periods, and on ever-decreasing budgets, organisations are betting on ATA to replace traditional tape storage instead of the more robust Fibre Channel or SCSI. But it's a risky bet.

The problem is simply one of choosing horses for courses. A close study of the form book will reveal that ATA is simply an extension of the PC archive disk. As such, it is best suited to archival storage duties where access is infrequent and for relatively short periods. It will simply not stay the course when asked to perform in organisation-wide situations where high-access, constant use information is the norm. It does not have the legs or the stamina and, sooner or later, it will fall at the fence. For demanding enterprise environments, Fibre Channel and ISCI are the only viable options.

On course for disaster
Relying on ATA for "industrial" type duties will ultimately result in disk failure and lost critical data. In any RAID disk array, disk failures may occur but data is recoverable from the other disks. However, while doing this, the workload of each of the remaining disks is, in effect, doubled. With ATA it is usually a constant and heavy workload that causes disk failure. Doubling the workload to other disks simply increases the likelihood of further breakdown with resulting data loss.

ATA can still play an important and valuable role within enterprise data storage, but it is best suited to low-access archive-oriented storage. The danger here is that even when ATA is bought and installed to perform the archival tasks for which it was designed, it can sometimes be press-ganged into providing temporary storage capacity. Space is allocated and the temporary requirement becomes permanent. The result - critical production data is now being stored and continually accessed on ATA storage.

It is only in the post-mortem that follows the disaster that people question why critical data was entrusted to simple and economical archiving technology.

Although Parallel ATA will soon be totally obsolete, Serial ATA will be a dependable technology for many years to come. But the use of SATA within the enterprise needs to be more clearly understood. IT Managers must distinguish between cost and value when choosing storage options. Using ATA to store critical enterprise data is a big gamble and, when it fails to pay off, some people are going to lose more than their shirts. ST