Re: SSDs have extra "unused" space??? (was: Re: Bug#735927: general: X *always* crashes when ram is full
On Tue, Jan 21, 2014 at 1:22 AM, Holger Levsen wrote:
> wait, what? Do you have any vendor statements to support this 20% extra space?
Flash is basically probabilistic storage and you need extra space to
ensure that the probability your data is stored remains high, and a
(possibly trustworthy) controller with algorithms in front to help
with that. Check out Bunnie's talk at 30C3 about SD cards where he
mentioned a 16GB flash device with the controller only saying it was
128MB in size (IIRC). I assume similar things apply to SSDs/NAND etc.
http://www.bunniestudios.com/blog/?p=3554
https://events.ccc.de/congress/2013/Fahrplan/events/5294.html
https://media.ccc.de/browse/congress/2013/30C3_-_5294_-_en_-_saal_1_-_201312291400_-_the_exploration_and_exploitation_of_an_sd_memory_card_-_bunnie_-_xobs.html
--
bye,
pabs
http://wiki.debian.org/PaulWise
Reply to: