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Am I right to assume that NAND flash has higher storage density than magnetic disks? I've been trying to find some definitive data about this but failed so far.

by riobard 11y ago

Am I right to assume that NAND flash has higher storage density than magnetic disks? I've been trying to find some definitive data about this but failed so far. I'd really appreciate if someone can point me the right direction to search.

deleted 11y ago
[deleted]
wmf 11y ago
Yes, flash density is much higher. Partly that's because putting circular platters in a rectangular case wastes a lot of space and partly because you can stack eight flash dies into a package around 1 mm thick.
- rikkus 11y ago
  Easy solution: square platters
  - rzzzt 11y ago
    Complete with read/write heads hanging off an X-Y plotter mechanism.
  - wmf 11y ago
    Either that or keep the platters circular but make the case hexagonal.
jyxent 11y ago
I found a paper from 2013 that compares storage densities up to 2012: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6558421 http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6... In 2012 they list the density of magnetic disks as 750 Gb/in^2 and nand flash as 550 Gb/in^2. I'm not sure how the numbers have changed with 2d nand, but 3d nand probably pushes the density way over magnetic.
- deleted 11y ago
  [deleted]
  - justincormack 11y ago
    No 3d nand is just a few layers for heat dissipation reasons not a giant chunk of storage.
barrkel 11y ago
Smallest height 2.5" HDD is 100x70x5 (35,000 mm^3), max size 4T MicroSD is 15x11x1 (165 mm^3), max size 200G MicroSD is less than 0.5% the volume of 2.5" HDD, but 5% of the capacity. So MicroSD is an order of magnitude more dense than 2.5" HDD. MicroSD still has to fit a little controller in there, so the comparison isn't particularly fair on flash. I expect heat management to be a problem scaling up though, apart from any manufacturing difficulties.
- mikeash 11y ago
  I was screwing around with writing firmware images to a micro SD card last night. Placed in a small USB adapter, the card got surprisingly hot after just writing a 4GB image to it. Fill a 2.5" form factor with the things and you'd probably start a fire.

by riobard 11y ago

deleted 11y ago

[deleted]

wmf 11y ago

Yes, flash density is much higher. Partly that's because putting circular platters in a rectangular case wastes a lot of space and partly because you can stack eight flash dies into a package around 1 mm thick.

rikkus 11y ago
Easy solution: square platters
- rzzzt 11y ago
  Complete with read/write heads hanging off an X-Y plotter mechanism.
- wmf 11y ago
  Either that or keep the platters circular but make the case hexagonal.

jyxent 11y ago

I found a paper from 2013 that compares storage densities up to 2012: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6558421 http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6... In 2012 they list the density of magnetic disks as 750 Gb/in^2 and nand flash as 550 Gb/in^2. I'm not sure how the numbers have changed with 2d nand, but 3d nand probably pushes the density way over magnetic.

deleted 11y ago
[deleted]
- justincormack 11y ago
  No 3d nand is just a few layers for heat dissipation reasons not a giant chunk of storage.

barrkel 11y ago

Smallest height 2.5" HDD is 100x70x5 (35,000 mm^3), max size 4T MicroSD is 15x11x1 (165 mm^3), max size 200G MicroSD is less than 0.5% the volume of 2.5" HDD, but 5% of the capacity. So MicroSD is an order of magnitude more dense than 2.5" HDD. MicroSD still has to fit a little controller in there, so the comparison isn't particularly fair on flash. I expect heat management to be a problem scaling up though, apart from any manufacturing difficulties.

mikeash 11y ago
I was screwing around with writing firmware images to a micro SD card last night. Placed in a small USB adapter, the card got surprisingly hot after just writing a 4GB image to it. Fill a 2.5" form factor with the things and you'd probably start a fire.