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Samsung's amazeballs 3D V-NAND SSD not THAT much better than predecessor

It's a real power-sipper, though

Samsung's mass-produced 3D vertical NAND (V-NAND) chip, in package

El Reg asked Samsung how the 3D V-NAND SSD's speed compared with the same company's SM843T 960GB SSD, a high-performance SSD used in data centres and servers released just a few months ago. The reply may surprise some hardened storage veterans.

3D V-NAND, announced on 7 August, stacks layers of NAND vertically to increase the capacity available in a set footprint.

Here's the reply:

Samsung's new V-NAND based 960GB SSD offers more than 20 per cent increase in sequential and random write speeds and 40 per cent improvement in power consumption, compared to the previous SM843T SSD.

This is the performance data we have on the SM843T SSD, which is built from 24nm Toggle-mode MLC NAND, by the way:

  • Up to 98,000 4K random read IOPS
  • Up to 15,000 4K random write IOPS
  • Up to 500MB/sec sequential reads
  • Up to 370MB/sec sequential writes

Therefore, a 960GB V-NAND SDD's bandwidth can handle more than 600MB/sec sequential reads and more than 444MB/sec sequential writes.

We don't know about its random read and write IOPS as Samsung didn't say, but can deduce that the numbers are not significantly more than the SM843T's or Samsung would have said so. Are they the same or, conceivably, less? We assume they are the same, for now but are left questioning the topic.

We are also asking ourselves, what is the lithography of the NAND cells in 3D NAND: 24nm, 21nm or less? Or more?

The sequential and random write speed increases are interesting but nothing to get excited about. Seagate's 1200 SDD, made with Samsung 21nm MLC NAND and in 200GB, 400GB and 800GB capacity points, offers 800MB/sec for reads and 640MB/sec for writes.

It's clear that 3D V-NAND doesn't offer more bandwidth or, for that matter, more capacity in a 2.5-inch SSD form factor - yet. V-NAND SSDs are a work in progress.

What would be interesting is the next capacity jump, using 3D V-NAND's layering technology bumped up beyond 24 layers, or a lithography shrink of the NAND cells in the layers, or both.

We wonder about the idea of 3D V-NAND built with triple layer cell NAND instead of the 2-bit MLC used now. That ought to be of huge future interest for capacity-centric NAND use, especially with V-NAND's 10x increase in endurance over 2D (planar) NAND. We also wonder what a PCIe flash card would look like using 3D V-NAND? ®

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