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Everything I Know About SSDs

kcall.co.uk

181–190 of 190 posts

Re: Everything I Know About SSDs

#181
post #3

I was under the impression that if you do not encrypt an SSD from the first use, then any attempt at overwriting with 0s is futile, as well as any other method to securely delete the files. The files will be easily recovered. This guy seems to say the opposite, in that the files are "simply not there anymore", contrary to everything I've read: who's right here?

>>The files will be easily recovered.

From my limited second-hand experience, it's the complete opposite. Data recovery services can't reassemble data from memory blocks of dead SSDs.

Re: Everything I Know About SSDs

#182
post #163

Earlier quoted context omitted.

If not for some very edgy heroics, it would have been millions, and most of Ukraine down to the Black Sea uninhabitable for centuries. What did happen was not just "because nuke", but because of a whole series of design and management failures, very far from the least of which was denialism. They did finally fix the cause of the explosion in the other reactors of that design, remarkably many years later. Nobody here…

If not for some very edgy heroics, it would have been millions That seems a tad unlikely. Nobody here will defend coal, but graphite-moderated reactors are not the tech you want to be defending. Exactly. And the reason we're stuck with 60-year-old reactor technology is...

There is a reason I mentioned "denial". The Central Committee shared your skepticism while they could. Ignorance is a luxury.

Re: Everything I Know About SSDs

#183

Earlier quoted context omitted.

> 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.

I remember reading a blog post ca. 2005, before SSDs were common, in which the author explained how he had identified all the files his system needed to boot and the order in which they were read from disk, and then contrived to put them all in the correct order in a contiguous block at the start of the drive to eliminate seeks during boot entirely. This apparently shaved a couple seconds off his boot time.

There are automated solutions to this.

Windows has had similar tricks built in (at various levels of cleverness, depending on the Windows variant you run) for a while now: https://en.wikipedia.org/wiki/Prefetcher

No doubt there are similar options for Linux and other OSs.

A similar trick I've seen is using a small SSD as a manual cache: copy in the files that need to be fast and mount it with the larger filesystem (on slower drives) as a unioned filesystem. Though just using block device based automatic cacheing may be easier and safer than rolling your own mess. There are a few options for Linux though some are not currently maintained (see https://serverfault.com/questions/969302/linux-ssd-as-hdd-ca... amongst other places), and some IO controllers support it directly (even some motherboards have this built in) without needing to bother your OS with the details at all.

Re: Everything I Know About SSDs

#184
post #9

Earlier quoted context omitted.

In practice all SSDs are always encrypted because they use the encryption to whiten the data written to them. That's why "Secure Erase" takes less than a second on SSDs, it doesn't erase anything but the key.

Interesting! Do you happen to know which encryption algorithm is used? I would think that, if the only goal is whitening (as opposed to robust security), a fairly weak algorithm would be used, or perhaps a strong algorithm with a reduced number of rounds.

It would need to be a fairly good algorithm to provide good "whitening", but they could be using a small or easy to guess/derive keys especially if the primary purpose is just whitening rather than security.

Re: Everything I Know About SSDs

#185
post #52
post #37

Earlier quoted context omitted.

There's a pretty succinct (2 minute) non-engineering description of how a nuclear reactor works in the Chernobyl miniseries you might want to check out: https://www.youtube.com/watch?v=BpwU4mtWXAE

Why is that scene so pointlessly edgy? Is the whole show like that?

In context - the scientist had basically said that the politicians and their bureaus were all wrong, that it wasn't a minor incident, and "accused" them of lying, covering up, and/or being willfully ignorant and stupid.

The whole show isn't like that, but it does try to show that so much of the issue was caused by a desire to be seen as infallible (of course the reactor design wasn't flawed, because the people's greatest minds worked on it, etc., etc.) and that was something that had to be dealt with atop the actual disaster.

Re: Everything I Know About SSDs

#186
post #182

Earlier quoted context omitted.

If not for some very edgy heroics, it would have been millions That seems a tad unlikely. Nobody here will defend coal, but graphite-moderated reactors are not the tech you want to be defending. Exactly. And the reason we're stuck with 60-year-old reactor technology is...

There is a reason I mentioned "denial". The Central Committee shared your skepticism while they could. Ignorance is a luxury.

Sorry, I don't have the faintest clue what argument you're making.

Re: Everything I Know About SSDs

#187

Earlier quoted context omitted.

archive.is links have not been working for me for a while now. I wasn't sure if something was wrong with the site or what, but seeing this link posted here convinced me to do a bit of digging. I have news: 1.1.1.1, aka CloudFlare's DNS, resolves archive.is to 127.0.0.5. Live proof: https://digwebinterface.com/?hostnames=archive.is&useresolve... Archived proof: http://archive.is/utJfW Of course the moment I changed 1.…

1.1.1.1 has been acting up for me recently as well but haven’t had a chance to investigate. Glad to hear it’s not just me

It’s really archive.is acting up here...

Re: Everything I Know About SSDs

#188
post #182

Earlier quoted context omitted.

There is a reason I mentioned "denial". The Central Committee shared your skepticism while they could. Ignorance is a luxury.

Sorry, I don't have the faintest clue what argument you're making.

Uninformed skepticism worth no more than the effort that was put into it.

Re: Everything I Know About SSDs

#190
post #118

thanks for writing. Is it me or someone else noticed that the font is too tough to read?

I am the author of kcall.co.uk/ssd/index.html and I trust that the site is now back up and running without further 'sleeping' episodes. The reason for the interrupts was, as some have surmised, that the site was mentioned here and in other places and that caused a surge in hits that exceeded the host's usage limit. Whilst I am pleased that so many people have shown an interest in my efforts it does mean that I have had to move the site to a more generous host.

It is apparent from the first sentence and the website itself that this article is, or arises from, tha musings of shall we say an amateur. It's not professional because I'm not a professional. Whilst some of the comments in this thread are helpful, some are baffling. To the person who couldn't get past the header bacause Comic Sans offended him, the following 8058 words were in Century Gothic, which is perhaps not so offensive. I have however accepted the comments on readability and changed the header and all the rest of the text to Calibri, made the font larger, and changed the line spacing to web standards. I hope it is now more soothing and readable. As for the claim that the text is 'spoiled by having dozens of typos and spelling mistakes' I'm not sure what he is reading (or smoking). Apart from the removal of one stray colon, the current text is entirely unchanged - it is the same file. I don't claim to be perfect and I'm sure that in such a large essay there are some typos and other errors, but to say that there are dozens is patently untrue. Just let me know where they are and I will happily correct them.

Apart from all that, I am surprised that there are so few comments about the veracity or otherwise of the contents. I had great difficulty in finding material that was up to date and actuially delved into the technicalities of SSDs, without baffling me - as much did.

I shall end by thanking those who found the article interesting and I hope that some of it at least has been of some help.

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