It turns out Samsung wasn’t the only company to have 16TB SSDs at Flash Memory Summit after all:
Now that I’ve got your attention, Novachips is an SSD company that does not make their own flash, but I would argue that they make other peoples flash better. They source flash memory wafers and dies from other companies, but they package it in a unique way that enables very large numbers of flash dies per controller. This is handy for situations where very large capacities per controller are needed (either physically or logically).
Normally there is a limit to the number of dies that can communicate on a common bus (similar limits apply to DRAM, which is why some motherboards are picky with large numbers of DIMMs installed). Novachips gets around this with an innovative flash packaging method:
The 16-die stack in the above picture would normally just connect out the bottom of the package, but in the Novachips parts, those connections are made to a microcontroller die also present within the package. This part acts as an interface back to the main SSD controller, but it does so over a ring bus architecture.
To clarify, those 800 or 1600 MB/sec figures on the above slide are the transfer rates *per ring*, and Novachips controller is 8-channels, meaning the flash side of the controller can handle massive throughputs. Ring busses are not limited by the same fanout requirements seen on parallel addressed devices, which means there is no practical limit to the number of flash packages connected on a single controller channel, making for some outrageous amounts of flash hanging off of a single controller:
That’s a lot of flash on a single card (and yes, the other side was full as well).
The above pic was taken at last years Flash Memory Summit. Novachips has been making steady progress on controller development as well. Here is a prototype controller seen last year running on an FPGA test system:
…and this year that same controller had been migrated to an ASIC:
It’s interesting to see the physical differences between those two parts. Note that both new and old platforms were connected to the same banks of flash. The newer photo showed two complete systems – one on ONFi flash (IMFT Intel / Micron) and the other on Toggle Mode (Toshiba). This was done to demonstrate that Novachips HLNAND hardware is compatible with both types.
Novachips also had NVMe PCIe hardware up and running at the show.
Novachips was also showing some impressive packaging in their SATA devices:
At the right was a 2TB SATA SSD, and at the left was a 4TB unit. Both were in the 7mm form factor. 4TB is the largest capacity SSD I have seen in that form factor to date.
Novachips also makes an 8TB variant, though the added PCB requires 15mm packaging.
All of this means that it is not always necessary to have huge capacity per die to achieve a huge capacity SSD. Imagine very high capacity flash arrays using this technology, connecting a single controller to a bank of Toshiba’s new QLC archival flash or Samsung’s new 256Gbit VNAND. Then imagine a server full of those PCIe devices. Things certainly seem to be getting big in the world of flash memory, that’s for sure.
Even more Flash Memory Summit posts to follow!