Measuring Performance Density

Measuring Performance Density
Why It Is the Key Benchmark to Measuring Storage Performance

Storage performance is confusing, and storage vendors don’t make it easy to know who delivers the best performance, or even what “the best performance” means. Look at any storage vendor's website and you will come away thinking that their product is the best. That is by design. Every manufacturer wants you to think they have the best product. That is what they are supposed to do.

So how can you tell which one really is the best? What does it mean to be “the best”? Let's take a look at some of the different ways storage is measured, so that you can identify which solution is right for your organization.

There are a several ways storage is measured:

Most Common:

    1. Performance
    2. Latency
    3. Capacity

Most Useful:

    4. Performance Density

Performance is how fast a storage system can put data out on the wire and is measured in gigabytes per second (GB/s) of throughput. The bigger the number, the better the performance.

Latency is the amount of time it takes a storage system to complete a read or write request. Latency is measured in either milliseconds (ms) or microseconds (µs). In this case, the lower the number, the better.

Latency is a tricky thing to measure, because not all latency measurements are equal. Some vendors only measure the latency of their device, while others measure the latency of the device and the storage network. To learn more about latency, read our earlier blog Truth and Accuracy in Reporting: The True Measure of Latency.

Capacity is the volume of data that the system can house. Storage array capacity is usually measured in either terabytes (TB) or petabytes (PB).

These are the most common ways of measuring the capabilities of a storage device and are all important things to consider. However, there is a more useful way to measure performance and it is performance density.

Performance density is a measure of performance received in a given amount of space in your data center. Performance Density can be measured in performance per rack units (RU). This may be the most overlooked measure of a storage solution, but as you will see, it may also be the most important.

Consider two different storage products. Both claim to be leaders in throughput, latency, and capacity. But one only takes up 4RU, while the other uses 80RU. It may sound like an extreme example, but this is a real world case that compares the Pavilion hyperparallel flash array with another competing solution,

Performance density is important because it is more than simply a measurement of rack space. Filling those 80RUs requires the purchase of multiple systems, driving up costs. All of those individual systems then need to be installed, cabled, powered, cooled, and managed over time. Each of those individual systems adds cost, complexity, and significantly more things to go wrong.

The challenge with measuring performance density is that it is rarely reported. So how do we measure it? To determine performance density, we must look at each storage solution and convert their performance to a common unit so that the comparison is fair. To come up with a fair performance density comparison, simply take a given performance measurement for each device and divide that by the total number of rack units that are required to achieve that number. The result is a fair measure of the performance for a given device that can be easily compared to any other storage system.

For example, the Pavilion HFA delivers up to 120GB/s of read throughput in a 4RU system. That means the Pavilion HFA has a per RU performance measurement of 30GB/s (120GB/s ÷ 4RU). In comparison, manufacturer published numbers for the system mentioned above states that it delivers 350GB/s in 80RU, which equates to 4.375GB/s per RU. As you can see, even though the other system data sheet had a throughput number of almost 3X Pavilion’s, when compared on a per RU basis, the Pavilion HFA is almost 7X faster. So performance density matters.

Every environment is unique, so the “best” storage will always be the one that meets the needs of your particular application. Sometimes that will be the Pavilion HFA, sometimes it won’t. But all things being equal, the best is the one that delivers the best combination of high performance, low latency, capacity, and density - the Pavilion HFA.

Contact us to learn more about how the Pavilion HFA is shattering expectations on performance.