At issue: SATA
The need for inexpensive, high-capacity storage media is growing. Serial ATA (SATA) hard disk drives are quickly becoming alternatives to higher-cost FC and SCSI drives for enterprises grappling with new compliance requirements and considering tiered storage strategies. SATA has evolved significantly from parallel ATA, but there are a number of issues that must be resolved before the drives can reliably support enterprise applications.
SATA drives deliver storage capacities equivalent to FC or SCSI drives, but for as little as a quarter of the price per gigabyte. SATA drives are also available with much larger capacities than FC or SCSI disks. The major question is whether SATA drives can satisfy enterprise-class availability, data integrity and performance requirements.
SATA evolved from the parallel ATA interface, which has been used mainly in desktop and entry-level server systems. However, the performance and reliability characteristics of ATA drives were simply not engineered for enterprise storage. SATA was developed to overcome some of the limitations of parallel ATA drives. SATA 1.0 delivered improvements in performance (1.5 gigabytes per second (GBps) dedicated bandwidth), cabling and reliability (hot plug/swap). SATA 1.0 drives support speeds up to 10,000 rpm and mean time between failure (MTBF) levels up to 1 million hours under an eight-hour, low-duty cycle. FC drives support up to 15,000 rpm and an MTBF of 1.4 million hours under a 24-hour duty cycle. But SATA's impressive cost advantage over FC has compelled many companies to deploy SATA in secondary and primary storage platforms, even in places where SATA may not yet be appropriate.
Four trends are driving the need for low-cost, high-capacity disk drives:
Enterprises are abandoning a one-size-fits-all approach to storage and moving toward tiered storage, where data is migrated to lower classes of storage as its business value depreciates. Many companies have introduced disk into their backup environments in an effort to hit tight backup windows and stringent recovery time/point objectives. Because the ratio of primary to secondary backup data in many environments is 1:10, the introduction of disk presents a number of economic challenges requiring a low-cost, high-capacity disk solution.
New regulatory compliance requirements mandate that businesses preserve electronic records for many years. Moreover, some of these regulations define specific recovery time objectives for data, which often means the data must be retained online. The explosive growth of online archive data sets, often into petabytes, is another driver for less-expensive disk drives.
Read more of this tip in Storage magazine.
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About the author: Alex Gorbansky is a senior analyst and consultant at the Taneja Group.
This was first published in May 2005