Data Center Tech Blog
Michael Kanellos

Editor-in-Chief at SanDisk

What’s one technique to lower the cost of storage?

Aluminum organic capacitors, according to Fritz Kruger, engineering fellow here at SanDisk®.

Why? Here’s what I learned from him in recent webinar titled “Disaggegation and Scale: Changing the Economics of Flash:”

Solid state drives typically contain tantalum capacitors to provide power in the event of an interruption., Tantalum’s are used because they are very small and there is limited amount of volume inside a traditional SSD case. A single tantalum capacitor, however, can add nearly $5 to the bill of materials of a drive, and there might be as many as 24 in each SSD. If you have multiple drives in an array or rack, that cost begins to escalate.

Aluminum organic capacitors cost around 50 cents each. Even better, these capacitors can increase reliability compared to the tantalum ones. The drawback is that they are physically larger. By taking advantage of the additional chassis space inside InfiniFlash, the all-flash array for Big Data released earlier this year, SanDisk was able to adopt aluminum capacitors to incrementally reduce the BOM cost of the array.

Flash is steadily undercutting the market for traditional hard drives through a convergence of increasing performance, declining costs and growing demand among customers for technology that can handle analytics and other complex workloads.

“The IOPS for hard drives has been relatively constant for a decade,” he said. “Flash bandwidth is parallelizable, depending on the width of the controller and the number of controllers…Flash bandwidth is an economic choice. Hard drive bandwidth is dictated by the physics.”

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In 2012, the total cost of ownership of flash systems dived below the cost of storage in part because of the ornate real estate, power and cooling required by hard drive storage-based systems. In 2014, flash systems dipped below the total cost of acquisition, i.e. capital costs, of drive-based systems because of the growing performance gap.

The growing gap makes the shift in some ways inevitable, but there’s also quite a bit of work going on at the rack, board and box level that is accelerating the transition.

Some of the notable highlights of the InfiniFlash design:

  • A fully populated 512TB InfiniFlash system contains 32,768 NAND die.
  • If you laid out the NAND chips from a complete system end to end, the silicon—not the packaging around the silicon, just the silicon—it would cover approximately 65 square feet.
  • InfiniFlash requires only a single controller per every 8TB of flash. (8TB fit on the internal card that slide into the 512TB chassis.) In most systems, there is a single controller for every 1.6TB, increasing costs.
  • Cases, connectors and other components were reduced to a minimum to maximize available space for storage in the 3U chassis (or in Kruger’s words: “We throw away any legacy of the hard drive form factor.”)
  • The sheer volume of storage inside the chassis mean that the impact of any unusable circuit blocks (found on all flash chips) is effectively eliminated. This permits SanDisk to integrate NAND from their leading-edge manufacturing processes rather than more expensive die from the trailing manufacturing processes, again making flash more attractive for enterprises.
  • Because SanDisk makes both the NAND die and the InfiniFlash system, they can focus their efforts on testing and characterizing the NAND for the thermal, electrical and environmental characteristics of data centers, in turn further lowering costs and speeding development.
  • A fully populated InfiniFlash system will provide 780K IOPS with latency at less than one millisecond and 1.1 million IOPS with latency at 2 milliseconds.

Making Flash Accessible

Flash is not another disk. I think Kruger explains that well: “We’re really finding that flash is becoming more and more necessary, not just replacing 15K to 10K drives. It is becoming more and more becoming a primary source of information because it is the only way to get at it fast enough.”

And the bottom line is “The more affordable we can make flash and the more accessible it is for our data centers the more use cases we can find.”

Take a break and watch his webinar on the InfiniFlash system, it’s riveting:

Solving Customers’ Key Challenges with Microsoft Channel Partners at WPC 2015

Flash at Scale: Ultra-Value SSDs in Hyperscale Environments

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