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All RAID is not created equal

Although there is nothing wrong with using low-cost arrays, careful attention needs to be paid to the actual components of the arrays.

Recently I talked to a shall-remain-nameless financial firm's IT planners who had pursued low-cost Serial ATA (SATA) array technology as a means of reducing storage costs. They had established a "multi-tier storage platform" (their words) and begun a laborious process of defining policies for migrating certain data from their expensive high end arrays to these cheaper RAID boxes based on data access requirements. Some SATA white boxes were designated as targets for data protection: eliminating backup windows by virtue of much faster disk-to-disk data copy speeds.

While there is nothing wrong with using low-cost arrays in these roles (as repositories for infrequently modified, but often accessed data) or as replication targets or tape backup surrogates, careful attention needs to be paid to the actual components of the arrays. All RAID is not created equal.

The client recently discovered this fact the hard way when an off-brand RAID-5 controller on a SATA array "lost its mind" following a firmware upgrade, and unbeknownst to the technicians, began corrupting all the data stored on its pennies-per-GB platters. While classified as "reference data" that was often accessed but rarely modified, the information stored on the array was nonetheless "mission critical" by virtue of the support it provided for certain key processes. Yet, the data protection requirements associated with mission critical data was obscured in the product evaluation and acquisition process by a myopic focus on platform cost.

For only a few dollars more, consumers can purchase SATA arrays with more resilient disk and RAID components. Too often it takes a failure to awaken planners to the need to consider data protection requirements in equipment selection.

So, the spring thaw is underway and, according to leading analysts, the market is showing some inclination toward loosening its purse strings a bit and spending some money on technology again. If this proves to be more than mere wishful thinking, an opportunity exists for organizations to begin making the right kinds of choices for a change: those that consider not only the scaling requirements for burgeoning data, but also the requirements for protecting the data entrusted to SANs and multi-tier storage platforms.

For more information:

  • Serial ATA adoption ramping up

  • SATA drives take aim at SCSI

  • Backup School

    About the Author: Jon William Toigo has authored hundreds of articles on storage and technology along with his monthly "Toigo's Take on Storage" expert column and backup/recovery feature. He is also a frequent site contributor on the subjects of storage management, disaster recovery and enterprise storage. Toigo has authored a number of storage books, including Disaster recovery planning: Preparing for the unthinkable, 3/e. For detailed information on the nine parts of a full-fledged DR plan, see Jon's web site at

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