SanDisk Releases Lightning PCIe SSDs for Enterprises

Computex is now running at full power and announcements are coming from everywhere. SanDisk just launched their latest addition to their enterprise storage portfolio: the Lightning PCIe SSA. SanDisk doesn't actually call the drive as an SSD, but as an SSA (Solid State Accelerator). The drive is based on SanDisk's own controller; if you've been following the enterprise SSD news closely, you might remember that SanDisk acquired a controller firm called Pliant about a year ago, and the controller is a fruit of that acquisition.

The actual controller is not new, though, as it's the same controller used in SanDisk's Lightning 6Gb SAS SSDs. It's a SAS based controller so SanDisk is using a SAS to PCIe bridge, which unfortunately limits the performance in some degree. SanDisk mentioned that the controller provides a lot more processing power than most of the competing controllers, and the aim is to handle as many I/O functions as possible so that the CPU will be free for application processing. SanDisk wouldn't reveal the specifics of the controller but Greg Goelz, the vice president and general manager of SanDisk's enterprise storage solutions, told me that while most controller have a few processing cores, SanDisk's controller has "plenty more".

SanDisk is a rare SSD company in the sense that they can make everything in the house. Toshiba and SanDisk established a NAND joint venture in 2010, which means SanDisk makes their own NAND now as well. Thus it's not surprising that the Lightning PCIe SSA series is using SanDisk's brand new 24nm SLC NAND.

The performance figures may seem disappointing but they aren't the whole story. Greg Goelz specifically told me that SanDisk wanted to be conservative with the numbers and not provide absolute maximums like many other companies do. SanDisk's goal was not to create the fastest SSA on earth, but rather an SSA that does well in all workloads and capacities. The biggest goal was to create an SSA with predictable performance. This means the performance must be the same regardless of how full the drive is. Given the price of enterprise SSAs, you don't want to spend thousands of dollars per SSA and then realize that you can't use all of its capacity or your performance degrades. Especially when it comes to first class storage such as SSAs, this is important because the more data you can store in SSAs instead of HDDs, the better the performance will be.

Another aspect that SanDisk emphasized was response times. Most companies only report their average response time, which actually doesn't tell you much. You can have an average response time of, for instance, 10ms, but the worst case response time can easily be over a second. SanDisk Lightning PCIe SSA has a maximum response time of 30ms, which is very low. Maximum response time is a crucial part of performance predictability as when you know the maximum response time, it's easier to sort out possible bottlenecks. Moreover, you will know that your SSA responds in a certain time regardless of the workload. Response times are often overlooked even though they can be the source of bottlenecks. Imagine that you're running a web server with an SSA that has a maximum response time of two seconds. When the user fetches data from the drive, most of the time the data might be readily available, but in certain cases it may take two seconds for the SSA to respond, plus the time it takes for the data to be read/written and transferred. Hence response time can have a huge impact on overall performance and shall not be ignored when configuring your system.

As for power requirements, the drive is powered by the PCIe slot and SanDisk is stating sub-15W power consumption even at full load. Power consumption actually plays a bigger role in the enterprise world than many would expect. Performance per watt is definitely one of the most important measures because when you have a system consisting of hundreds or even thousands of individual servers, all of which can have several PCIe SSAs, saving even 5W per drive can lead to massive savings over time. Low power consumption also means less heat, which makes the drive compatible with more systems. A higher power drive may need a certain amount of air flow to stay within safe temperatures and figuring out whether your system provides enough air flow may not be an easy job. 

Operating system support is fairly broad as well since the Lightning PCIe SSA supports Windows, Linux and VMWare ESX environments. No additional configuration or software is needed; the drive is essentially plug and play. SanDisk mentioned availability as June in the US and Japan, and it will be available from major resellers such as NewEgg and TigerDirect. We are looking forward to reviewing the Lightning PCIe SSA series, so stay tuned!