Everything I Know About SSDs • Hacker News Board

Re: Everything I Know About SSDs

#41

Post by computator » Wed, Jan 15, 2020, 5:04 PM UTC

> Deleted file recovery on a modern SSD is next to impossible for the end user

OK, he’s talking about SSDs, but I want to mention that I’ve easily recovered many large deleted files from SD or micro-SD cards (formatted as FAT32 or exFAT) using Norton Unerase or an equivalent utility.

Are the controllers for SSDs that different from the controllers for SD cards? Has anyone tried Norton Unerase or an equivalent program on an SSD? I’d like to hear a first hand account to help confirm (or deny) what the author claims.

Re: Everything I Know About SSDs

#42

Post by leetcrew » Wed, Jan 15, 2020, 5:04 PM UTC

cm2187 wrote: post #38

leetcrew wrote: post #33

Earlier quoted context omitted.

I don't mean to say it wouldn't work, just that I don't know enough about sd cards to say whether it would/should.

Sorry, I meant for TRIM being passed down to an SSD.

oh gotcha. not sure why I thought it was reasonable to think you were talking about a bunch of SD cards in a raid array...

Re: Everything I Know About SSDs

#43

Post by cattlemansgold » Wed, Jan 15, 2020, 5:16 PM UTC

24gttghh wrote: post #14

cattlemansgold wrote: post #8

There are a few technologies that I’ve tried very earnestly to understand, only to find out that it’s basically black magic and there’s no use in trying to understand it. Those things are modern car transmissions, nuclear reactors, and SSDs.

A very basic nuclear reactor can be explained pretty simply I think. You enrich a bunch of let's say uranium. Pack it together in a rod, and put a bunch of those rods in a pond. Those rods have controlled (ideally) nuclear decay from their being in close proximity to other rods which generates a lot of heat, which is transferred to a separate cooling loop that boils water to make steam which drives an electric turbin…

I guess what I meant is that the overall concepts are understandable. Nuclear fuel gets hot, boils water, drives a turbine. For transmissions, different sized gears allow things to turn at different rates.

But as soon as I dive into the details, I get lost. How exactly can you control the nuclear decay? How exactly does do the gears in the transmission move around and combine with eachother to create a specific gear ratio? These concepts probably are probably pretty simple for a lot of people, but they just make my head spin.

Re: Everything I Know About SSDs

#44

Post by computator » Wed, Jan 15, 2020, 5:21 PM UTC

cbdumas wrote: post #30

I love a minimal, text-only website as much as the next crotchety HN reader, but a little bit of CSS goes a very long way in terms of readability. Edit: Upon further inspection I see that this page was designed to be hard to read. Very curious.

If the author is reading this, I’d like to ask him to please run his article through a spell checker. All the effort to write a nice article is spoiled by having dozens of typos and spelling mistakes.

Re: Everything I Know About SSDs

#45

Post by dr_zoidberg » Wed, Jan 15, 2020, 5:22 PM UTC

occamrazor wrote: post #32

cbdumas wrote: post #30

I love a minimal, text-only website as much as the next crotchety HN reader, but a little bit of CSS goes a very long way in terms of readability. Edit: Upon further inspection I see that this page was designed to be hard to read. Very curious.

Reader view helps a lot, and with such a simple website it is guaranteed to give a good result.

Not just a lot, it actually makes it readable. However I do feel this article needs a few graphs and diagrams. I've written [0] about data recovery and SSD/Flash storage is a massive beast to tackle even with diagrams to give you a vague idea of what's going on.

[0] in old fashioned tree-based paper, unfortunately

Re: Everything I Know About SSDs

#46

Post by 867-5309 » Wed, Jan 15, 2020, 5:23 PM UTC

occamrazor wrote: post #32

cbdumas wrote: post #30

I love a minimal, text-only website as much as the next crotchety HN reader, but a little bit of CSS goes a very long way in terms of readability. Edit: Upon further inspection I see that this page was designed to be hard to read. Very curious.

Reader view helps a lot, and with such a simple website it is guaranteed to give a good result.

not if you're reading via Materialistic via Android browser with no responsive design or zoom ~,~

Re: Everything I Know About SSDs

#47

Post by gowld » Wed, Jan 15, 2020, 5:25 PM UTC

cbdumas wrote: post #30

I love a minimal, text-only website as much as the next crotchety HN reader, but a little bit of CSS goes a very long way in terms of readability. Edit: Upon further inspection I see that this page was designed to be hard to read. Very curious.

How so? It's a nice single column of test on my mobile.

Re: Everything I Know About SSDs

#48

Post by m4rtink » Wed, Jan 15, 2020, 5:25 PM UTC

24gttghh wrote: post #14

cattlemansgold wrote: post #8

There are a few technologies that I’ve tried very earnestly to understand, only to find out that it’s basically black magic and there’s no use in trying to understand it. Those things are modern car transmissions, nuclear reactors, and SSDs.

A very basic nuclear reactor can be explained pretty simply I think. You enrich a bunch of let's say uranium. Pack it together in a rod, and put a bunch of those rods in a pond. Those rods have controlled (ideally) nuclear decay from their being in close proximity to other rods which generates a lot of heat, which is transferred to a separate cooling loop that boils water to make steam which drives an electric turbin…

What you describe is basically a radioisotope thermal generator, like those used by space probes. In such a device, you use natural decay heat of unstable radioisotopes.

In a nucler reactor, things are a bit different. You start with uranium that is only slightly rsdioactive and does not produce any usable quantities of heat. You place in ib the corrrct geometry and start a controlled nuclear chain reaction. You jave neurons split uranium, which produces heat and more neutrons.

Controlling this reaction so that it actually runs runs, but not so much as to melt your reactor is what, as far as I understand it, makes nuclear reactor design hard.

Re: Everything I Know About SSDs

#49

Post by thejj100100 » Wed, Jan 15, 2020, 5:26 PM UTC

gowld wrote: post #47

cbdumas wrote: post #30

I love a minimal, text-only website as much as the next crotchety HN reader, but a little bit of CSS goes a very long way in terms of readability. Edit: Upon further inspection I see that this page was designed to be hard to read. Very curious.

How so? It's a nice single column of test on my mobile.

It's a wide column of text on a larger screen - usually text is centred in the middle.

Re: Everything I Know About SSDs

#50

Post by rckoepke » Wed, Jan 15, 2020, 5:27 PM UTC

notacoward wrote: post #2

The part about filesystems is slightly incorrect. > The way the file system handles this is incompatible with the workings of NAND flash. That's true of most conventional filesystems, but log-structured filesystems are much more flash-friendly. That's why there has been a resurgence of interest in them, and also why a typical flash translation layer bears a striking resemblance to a log-structured FS. There are also…

> to an HDD all sectors are the same.

Also I believe some humans, and (filesystems?) intentionally stored certain data towards the inside/outside of the HDD because the simple cylinder geometry allowed faster reads in those regions. However, I'm not seeing conclusive proof that modern HDDs show performance variation with respect to radius.