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Some Numbers: Performance and Power Consumption

SSD 102: The Ins And Outs Of Solid State Storage

There is no alternative to studying reviews and comparing comparative information before purchasing SSDs, especially if you’re looking for a larger number of drives for servers. All manufacturers promise 230+ MB/s and 180+ MB/s read and write throughput, as well as thousands of I/O operations per second for their drives. While most products deliver on these expectations when it comes to peak performance, the minimum and average performance numbers can be significantly lower. This means that you should always be planning with minimum performance numbers in an effort to avoid issues in your business environment. In the end, a drive that usually writes at around 200 MB/s will still be unsuitable for high-performance environments, even if it might drop to 40 MB/s here and there.

I/O Enables Our Digital Lives

Eventually, it does not matter too much whether an SSD reads at 220 or at 250 MB/s, or if it writes at 210 or 180 MB/s. Only hardcore enthusiasts will be able to tell a difference. However, SSDs make much more of a difference in enterprise scenarios where ridiculous amounts of I/O operations per second are way more important than throughput.

If you think about how many users log on to Web services at any point in time, you'll realize that we’re discussing a number of I/Os that no one can grasp anymore. Facebook alone reputedly has some 400 million active users, and each of their login requests trigger many read and write operations. Despite this massive traffic, we still expect immediate responses to all of our clicks and requests. Now consider how your digital footprint spreads: logins across various Web sites, analytics, tracking, reposts by other users, on and on. You get the point. We need SSD-class performance to help manage this data avalanche.

Power Consumption

The same thinking applies to power consumption. Why should we care if drives with less than 0.1 W idle power go from 2 W to 1.5 W from one SSD generation to the next? With laptops, this is indeed mainly relevant only for road warriors who want maximum battery runtime. But from a global perspective, especially including data centers, each watt can matter. According to IDC, servers worth $42.2 billion were purchased in 2009. The cost for power required to operate those servers was $32.6 billion. Every watt of power required to run data center hardware requires 2.5 W of additional power for cooling.

Where To Go?

Clearly, the metrics are changing. Whereas companies used to look at gigabytes or performance per dollar, today's managers are more interested in I/Os per dollar, I/Os per watt, and sometimes gigabytes per watt. These metrics clearly favor of SSDs. In the end, what matters is expanding data center performance and capacity without physically expanding the data center itself.

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