Previously I wrote about the importance of “scalable performance” when it comes enterprise storage. My point: Enterprise-class SSDs must have sufficient back-end horsepower to scale I/O performance to meet increasing workloads for today’s data-throughput intensive applications.

Pliant recently ran a series of performance tests on several storage devices, and the results were eye opening. For baseline reference, see what happens to a typical enterprise 15K RPM hard drive as the workload increases:

Once the HDD reaches 400 IOPS, the response time starts to increase considerably to more than 75,000 microseconds (μs). And, as it reaches 500 IOPS, the response time nearly doubles, reaching more than 137,000 μs. This is the expected behavior for a mechanical device, limited by a single actuator.

Generally speaking, SSDs offer better raw I/O performance than HDDs, but when it comes to scalability and managing response time, the results are startling:

The chart above compares the STEC ZeusIOPS SAS SSD against the Pliant Lightning™ LS 300S EFD using the same saturation plot. As the workload increased, the STEC SSD’s response time increased dramatically, reaching as high as >10,000 microseconds, without significant scaling of I/O bandwidth. In contrast, the Pliant LS 300S was able keep response time below 2,000 microseconds and continued to scale I/O bandwidth to more than 32,000 IOPS.

This is the reason we designed Pliant’s Lightning Enterprise Flash Drive (EFD) to provide steady, predictable performance over time regardless of workload:

Data center I/O demands are dynamic and unpredictable by nature. As such, enterprise storage devices must have the power and flexibility to scale on-the-fly to provide a high level of performance at all times and under all workloads.

C.T. Chu

We’ve been participating in Bell Micro’s SSD Seminar Series to help educate enterprise IT managers, OEMs, and storage and IT system developers on the significant performance, reliability and cost advantages of next-generation solid-state storage technology.

The seminars have been held in cities across North America (Toronto, Montreal, Boston, Bethesda, and Minneapolis), and the final one is scheduled for this Thursday, Dec. 3, in Milpitas, CA. Four SSD suppliers, including Pliant, will be presenting on the multiple benefits of adding SSDs to the storage infrastructure.

Not surprisingly, there’s quite a bit of expectation and discussion at the seminars that SSDs can deliver significantly higher I/O performance than hard drives. However, what’s surprising to me, having done five of the six seminars, is that people are already talking about “performance droop in SSD over time.” One of the vendors even stated, “fresh-out-of-box performance is different than steady-state performance.”

Now, I will spare you the discussion on how garbage collection affects SSD performance over time, as there are already plenty of articles on this subject. What is most troublesome is that performance droop should not occur at all. Solid state drives are supposed to alleviate performance bottlenecks, not introduce new ones. As such, a properly designed SSD controller should and must have sufficient horsepower so that a critical function like garbage collection will not impact I/O performance.

While we’re on the subject of performance, let’s talk about scalable performance.

Advanced interfaces, such as Fibre Channel (FC) and Serial Attached SCSI (SAS), provide access to two ports. For years, the secondary port has been relegated to sitting idle, used only when the primary port failed.

That’s a shame…and a waste, in my opinion.

Both the FC and SAS interfaces allow performance to scale when both ports are actively used. Given the fact that solid state drives are not physically constrained by a single read/write head, one should expect to scale performance by reading and writing to both ports at the same time!

The below charts illustrate the point:

You paid for both ports already. Why not actually use both?

If you would like to learn more about “scalable performance” and how you can best implement enterprise SSD storage in your IT infrastructure, I invite you to join me and the Bell Micro team at the seminar this Thursday. It will be held at the Crowne Plaza Hotel in Milpitas, CA.

You can find more detailed info here:  http://www.bellmicro.com/ssd/seminar.asp.

I look forward to seeing you there!

C.T. Chu