
Samsung Announces 512GB NVMe SSD That's Smaller Than a Stamp - aaronbrethorst
http://www.macrumors.com/2016/05/31/samsung-ultra-small-nvme-512gb-ssd/
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justinsaccount
I've been wondering something about SSD density...

Today, ignoring this new drive, you can buy a 1TB m.2 SSD that is 1/20th the
size of a 2.5" disk, but the largest 2.5" SSD samsung sells is 2TB. It always
seemed odd that the drive 20 times larger in physical size only has twice the
capacity as the postage stamp sized version.

I wonder how large of a 2.5" disk samsung could make if cost was not an
obstacle... maybe this drive (that you can't actually buy yet) is what you
would get?

[https://news.samsung.com/global/samsung-now-introducing-
worl...](https://news.samsung.com/global/samsung-now-introducing-worlds-
largest-capacity-15-36tb-ssd-for-enterprise-storage-systems)

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pkaye
The biggest consideration in this is the NAND bus loading on the controller.
Typically a controller has 4-16 NAND buses. Each bus is about 16 IO pins
(8-bit bus plus control signals) Each bus can drive 8 NAND die at full speed.
By lowering the speed, you can drive 16 NAND die. With more NAND buses at high
speed you have to worry about power routing and signal integrity issues so
there is a limit to this. Typically each NAND package has 4-8 NAND die inside
it so commonly you will see one NAND package per channel. Also you need to
scale the DRAM with NAND capacity usually linearly. What happens in the end is
the total number of channels is fixed by the number of die per channel varies
from 2-8 dies. With each generation, the capacity of a single die increases.
To increase beyond this, you general reduce the clock speed on the NAND bus
which explains why the higher capacity SSD have slightly slower performance.

There has been some effort to switch NAND to serial protocol to lower IO count
but it hasn't caught on. What Samsung is doing with multi die packages is very
common (one company I worked for did it 10 years ago) but there are concerns
with signal integrity and thermal limits to consider. It will generally have
slower performance than the full models or use power throttling to keep within
limits (good for burst workloads.)

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peterburkimsher
I have a 512GB SanDisk SD card.

The SSD is much faster, but there's no BGA socket on the side of my laptop.
There is an SD slot.

Judging by the dimensions, I think it might be just possible to make a 1 TB
SDXC card using the same silicon as Samsung's new SSD. Now that would be
interesting. It would need a different (non-BGA) package though, and it would
still be a tight fit. I'm looking forward to 10 nm.

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mmf
That's great news but: 900MBps != 5GB/3sec. Plus last time I checked (2 years
ago) write power for flash was about 10W/GBps and growing over time. So I
expect these speeds not to be sustainable for extended periods of time.

