Flash SSDs + RAID = Mind-Blowing Storage Performance
Some months ago, we were informed by A&R Edelman, Samsung’s PR agency in the US, about a YouTube video showing 24 Samsung PB22-J flash SSDs configured in a RAID array using a high-end PC. The guys who produced the video did a great job and reached just beyond 2 GB/s using one Adaptec 5-series controller card and an Areca 1680ix board on an Intel dual-CPU "Skulltrail" system. We felt intrigued by the project and decided to see if we could beat their results.
Why So Much Storage Performance?
The project makes sense if you look at it from one of two ways. You can take it as a fun exercise where money is no object, or you can view it with a longer-term outlook to see what future storage products could have in store. The promotional Samsung video shows what the impact of a super-fast SSD array could be. The array is capable of loading applications in a fraction of the time required today, and it effectively eliminates all storage-related performance bottlenecks. But it remains obvious that using 24 (or even 16 drives, as we did), is an impractical scenario on the desktop.
However, the situation is different on higher-end servers, where a maximum amount of I/O operations per second (IOPS) may be imperative for mission-critical applications. We decided not only to use a large number of flash SSDs, but we also wanted to use the best flash SSDs to trounce Samsung’s throughput numbers while also providing sensationally high IOPS numbers.
Our choice was Intel’s X25-E flash SSD, which is based on more expensive single-level cell (SLC) flash memory. Compared to Samsung’s multi-level cell (MLC) flash, SLC can provide shorter latencies and higher throughput for both reads and writes. One drawback remains: while Samsung’s PB22-J provides a massive 256 GB capacity, Intel’s X25-E professional SSDs still max out at 64 GB. Fortunately, the capacity difference didn’t matter in our race for performance, as only 16 of Intel’s flash SSDs were enough to beat the 24 drives used in Samsung’s video.
Let’s Get It On!
Intel was interested to take on the challenge and provided sixteen 64 GB X25-E drives for this article. Meanwhile, we asked Adaptec to provide two 5805 PCI Express RAID cards. With these, we created a nested array consisting of two RAID 0 hardware RAIDs, which we then used to create a Windows-powered software RAID 0 array across them. Our approach worked very well, as you’ll soon see.