George Crump of Storage Switzerland shot another chalk talk video, the subject of this one is sharing solid state storage. George added it to his article from a month ago where he shared his thoughts on Violin's certification with IBM SAN Volume Controller (SVC).
What about PCIe cards?
Another option is to pack as much flash as possible onto a PCIe card to sit in a high speed slot on a server. Because of their much higher interface speeds, PCIe cards have much better performance than your typical commodity SSD, but face their own unique issues. To speak with the Operating System (OS) PCIe cards require specialized software drivers. With some cards these drivers are so heavy-weight that their vendors don't even call them drivers anymore but try to convince you they are a great value added software layer. That might be true except for the fact that those cards gain their performance by stealing CPU cycles from the core that’s hosting it, the same core running the business software your trying to accelerate.
In my last post I discussed a few of the technical aspects of flash that make it a unique storage media, particularly the complexity of garbage collection. Here we take a look at flash packaging and how that impacts architectural decisions. For this post I’ll focus on the question: “Should I use commodity SSDs?” and move on to PCIe cards and Enterprise Flash Drives in subsequent posts.
It’s easy to see why HDD form factor SSDs seem attractive: they have the same look and feel as a regular disk drive, they do usually weigh less, and they fit in the same HDD connectors you have in your existing server. That's all you need to see great flash speed, right? Sure they look good in the benchmarks, and while some benchmark sites have become a lot more sophisticated in measuring SSD performance, the SSDs have also become more sophisticated at Specsmanship.
Flash is coming to the data center. Contrary to perception 18 months ago, now this seems to be accepted as ‘common knowledge.’ There is still much discussion around what that flash will look like and in what form it will be consumed. I plan to write a series of blogs describing the unique challenges involved in building large flash Memory Arrays and some of the decisions made along the road. A good place to start with is the “let’s build it myself” group of folks and the challenges they will encounter.
The very adventuresome amongst you might start with, "I'll just make my own".