Computerworld - I hear lots of talk about tiered storage strategies. Usually it's along the lines of one tier for high-performing applications, another tier for lower-performing ones and yet another for stagnant data.
That's a pretty simple way of looking at storage tiers. As SANs grow, different storage needs for applications emerge. Some applications require storage arrays with high availability but not high performance or capacity. Others need high capacity but don't have high availability or high performance. None of these specifications neatly maps to Tier 1 or 2 arrays.
Of course, monolithic arrays provide a shortcut to analyzing application requirements, but how much money is one willing to spend? They cover most application requirements, but spending $30,000 on 1TB of storage for a $5,000 server can be a stretch.Yet traditional Tier 2 storage arrays may fail to meet even an inexpensive server's availability requirements.
Because of trade-offs like this, vendors offer more arrays that do not neatly fall into a specific tier but are better classified as "one minus" and "two plus" tiers. As a rule of thumb, "one minus" storage arrays are usually trimmed-down versions of larger monolithic arrays. These storage arrays usually sacrifice high capacity in order to deliver the high availability and performance certain applications need. "Two plus" tiers are generally aimed at those applications that don't need high availability (five 9s) but require either high performance or capacity.
With application needs constantly changing, it's more important than ever to analyze and understand application requirements before buying storage. With "in between" storage tiers on the rise and the savings related to downgrading even a half tier substantial, companies need to continually examine their application requirements to see if and when one of these in-between tiers may be a better organizational fit.
Jerome Wendt currently works as a storage engineer and storage analyst. He contributes regularly to a variety of industry trade publications and can be reached at jerome.wendt@att.net.
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