Storage architects realized early on that speedy SSDs work perfectly for caching hot data stored in large pools of sluggish HDDs. Storage arrays beam the most important data up into flash storage, where its performance is increased by leaps and bounds. It also made financial sense to use the relatively expensive flash to boost the cheap and deep HDD storage. But times have changed.
The price of NAND continues to plummet, and suddenly there are blistering fast all-flash arrays that cost less than .50 cents per GB. Unfortunately, even the most powerful all-flash arrays can choke on tiny bits of metadata.
Flash is fast, but there are faster memory technologies. This means that there are ways to boost all-flash array performance; but if you have to cache for flash, you need something faster than flash.
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DRAM is the go-to type of memory -- it is orders of magnitude faster than even the fastest SSD -- but it loses data when power is removed. For mission-critical applications, the possibility of losing data during a power loss is unacceptable.
PMC-Sierra solves this problem by strapping on a bit of NAND to back up the DRAM if power is lost. A supercapacitor provides enough auxiliary power to flush the data held in DRAM, which protects the data.
This provides over 10 million IOPS when the DRAM is addressed as memory, or 1 million IOPS when the card is addressed as a standard NVMe storage device. PMC's Flashtec NVRAM drive already serves as the engine for the fastest all-flash arrays on the planet. Come along to Tom's IT Pro as storage hits Warp 10 in our PMC-Sierra Flashtec NVRAM Drive Review.
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Paul Alcorn is a Contributing Editor for Tom's IT Pro, covering Storage. Follow him on Twitter and on Google+.
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