SSDs and TCO

Shed some light on your SSD decisionOne of the best arguments to use an SSD is also one of the most difficult ways to sell anything.  This is the Total Cost of Ownership, commonly abbreviated to “TCO.”

TCO has been used as an argument for buying anything from compact fluorescent bulbs to Jaguar automobiles.

The argument usually revolves around an item whose initial price is higher, but which has lower ongoing (or operating) costs, and when these costs are combined, the higher-priced item proves to cost less to own over the long run.  In the case of a compact fluorescent (CF) bulb, the bulb may cost $7, versus $1 for an incandescent bulb, but it consumes 18 Watts compared to the 75 Watts consumed by the incandescent bulb it replaces.  In addition the CF bulb lasts ten times as long (10,000 hours vs. 1,000 hours.)  This works out to a savings of 470 kWh – or about $50 – plus $3 in bulb costs.

If consumers can save $53 by using CF bulbs instead of incandescents, then why do incandescent bulbs still out-sell CFs?  The simple answer is that the initial outlay is greater, and the TCO argument is too abstract for consumers to warm up to.

Objective Analysis finds the same to be true with SSDs.  Converting from an array of HDDs to an SSD in an enterprise system saves power, cooling, rack space, and in some cases even software licensing fees.  If there are fewer drives in the SSD-based system there are also fewer points of failure, improving reliability and lowering costs there.  There are more abstract methods like Server Consolidation that amplify those effects.

The TCO arguments for SSDs in PCs are less straightforward.  Replacing one HDD with one SSD looks unattractive until the user factors in productivity gains stemming from faster system speed and longer battery life.

The Storage Networking Industry Association – SNIA – has posted an enterprise SSD TCO calculator on its website.  This Excel model takes inputs on drive prices, IOPS figures, and many other parameters to help the user estimate total savings from the use of an SSD as an alternative to one or more HDDs.

Still, this is an approach that may be sound, but is seldom the reason that an IT professional adopts SSDs.  Instead it is more typical for the IT professional to try an SSD based simply on the fact that it solves a pressing problem for an initial cost that is comparable to or lower than the cost of the HDD system it replaces.

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