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Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD?

Cross-posted to 3 groups.

Followups directed to: comp.os.linux.advocacy, comp.os.linux.embedded, uk.comp.os.linux

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David Brown wrote:

> On 23/03/12 16:46, 7 wrote:
>> Chris Davies wrote:
>>
>>> 7<email_at_www_at_enemygadgets_dot_com@enemygadgets.com>  wrote:
>>>> Who says Linux had to format an SSD and why???????????
>>>
>>> Presumably you do, and on that basis you should be the best placed to
>>> answer the second part of the question...?
>>>
>>> Chris
>>
>>
>> Thank you for that lead in! :-)
> 
> 
> And how about a lead out - maybe you'd like to try and learn something
> about SSDs, flash, disks, filesystems, ram, and pretty much everything
> else you've got wrong here before continuing?


If any of what you rant about has anything to with reality or is
in with the topic, invite yourself back.



>> My problems are these:
>>
>> 1. SSDs are randomly accessible with no moving parts
>>     They are just slower versions of RAM.
> 
> They are not randomly writeable, unlike RAM.
> 
>>     RAM is not formatted, but still just as easy to use!
> 
> RAM used for filesystems /is/ formatted.  That is how it can work as a
> filesystem.
> 
> Formatting is just a matter of setting up a basic structure on the
> disk/flash/ram block so that the OS can reliably store and retrieve
> data.  That's all - and that's all that is done with SSD's too.
> 
>>
>> 2. SSD read sectors can be 4K, erase sectors may be 512k
>>     This will strain every known file system approach.
> 
> Erase sectors are not usually so big, but they are still big.  And write
> sectors are also perhaps 4K.  This means you can't write less data than
> that - flash is not randomly writeable, in the way RAM is.
> 
> Reading and writing 4K blocks at a time sounds quite like current large
> hard disks to me.
> 
>>
>> 3. SSDs sectors need erasing before writing.
>>     This doubles the work load for an MMU which at the
>>     moment skips and dances around the issue.
> 
> It is not work of an "MMU".  The SSD controller has to handle block
> erasing, fragmentation, re-mapping, wear levelling, etc.  This will
> always be the case for flash (if the SSD controller doesn't do it, the
> OS must do it - as it does with bare-bones flash filesystems like jffs2).
> 
>>
>> 4. Damn hard to properly format and read/write SSDs in an embedded
>>     system which adds layers of overhead.
>>
> 
> It is not a challenge at all.  If you are using embedded Linux, you can
> format, read and write SSDs just like any other media.  If you are
> working on minimal sized embedded systems, you can use a simpler system
> like FAT.
> 
>> 5. Linux is built with an MMU in mind, but with an SSD, an MMU is
>>     extreme waste and extreme overhead.
>>
> 
> MMUs are part of the system of directly accessing memory - SSDs (and
> other flash) is not directly accessed, and the MMU is not involved.
> Throwing around technical terms that you don't understand does not make
> you look any better.
> 
>> 6. Database support overhead is next to impossible to handle
>>     in a small embedded system if a filing system is present.
>>
> 
> You've pulled that claim out of thin air, without showing any knowledge
> of databases, filesystems, or embedded systems.
> 
> The whole point of using embedded Linux is that you can use Linux
> software - including databases (big ones like Postgresql, small ones
> like sqllite, or whatever) in exactly the same way as you would on a
> non-embedded Linux system.
> 
> It is fair to say that if you have an embedded system with directly
> connected flash (NAND or NOR), and you have a particular simple database
> requirement (say, a logging system), then you could be more efficient by
> having a simpler structure on the NAND rather than a full-blown
> filesystem.  But that would not be an SSD.
> 
> <snip more nonsense>

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Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? 7 <email_at_www_at_enemygadgets_dot_com@enemygadgets.com> - 2012-03-22 19:29 +0000
  Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? unruh <unruh@invalid.ca> - 2012-03-22 20:14 +0000
    Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? 7 <email_at_www_at_enemygadgets_dot_com@enemygadgets.com> - 2012-03-22 20:16 +0000
      Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? Peter Köhlmann <peter-koehlmann@t-online.de> - 2012-03-22 21:31 +0100
        Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? 7 <email_at_www_at_enemygadgets_dot_com@enemygadgets.com> - 2012-03-22 20:43 +0000
          Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? Peter Köhlmann <peter-koehlmann@t-online.de> - 2012-03-22 21:52 +0100
            Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? "Henk & Ingrid" <Henk_Ingrid@invalid.invalid> - 2012-03-22 22:56 +0100
              Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? Foster <frankfoster50@yahoo.com> - 2012-03-22 22:04 -0400
      Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? unruh <unruh@invalid.ca> - 2012-03-22 21:14 +0000
        Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? 7 <email_at_www_at_enemygadgets_dot_com@enemygadgets.com> - 2012-03-22 22:46 +0000
          Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? Hadron<hadronquark@gmail.com> - 2012-03-23 16:29 +0100
          Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-03-26 23:43 +0300
            Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? hamilton <hamilton@nothere.com> - 2012-03-26 16:03 -0600
              Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? unruh <unruh@invalid.ca> - 2012-03-27 02:38 +0000
      Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? 7 <email_at_www_at_enemygadgets_dot_com@enemygadgets.com> - 2012-03-23 15:39 +0000
        Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? "Ezekiel" <zeke@nosuchemail.com> - 2012-03-23 12:55 -0400
          Meet Ezekiel - Burson-Marselar employee trolling Linux Newsgroups 7 <email_at_www_at_enemygadgets_dot_com@enemygadgets.com> - 2012-03-23 17:10 +0000
          Meet Ezekiel - Burson-Marselar employee trolling Linux Newsgroups 7 <email_at_www_at_enemygadgets_dot_com@enemygadgets.com> - 2012-03-23 17:10 +0000
            Re: Meet Ezekiel - Burson-Marselar employee trolling Linux Newsgroups "Ezekiel" <zeke@nosuchemail.com> - 2012-03-23 13:15 -0400
  Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? Chris Davies <chris-usenet@roaima.co.uk> - 2012-03-22 20:25 +0000
    Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? 7 <email_at_www_at_enemygadgets_dot_com@enemygadgets.com> - 2012-03-23 15:46 +0000
      Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? David Brown <david.brown@removethis.hesbynett.no> - 2012-03-23 22:27 +0100
        Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? 7 <email_at_www_at_enemygadgets_dot_com@enemygadgets.com> - 2012-03-23 21:42 +0000
          Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? "Ezekiel" <zeke@nosuchemail.com> - 2012-03-25 09:08 -0400
  Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? "Ezekiel" <zeke@nosuchemail.com> - 2012-03-22 17:18 -0400
    Re: Next year will see 100GB SSD cheap as chips, but why does Linux need to format an SSD? Greg Hennessy <me@privacy.org> - 2012-03-23 23:02 +1100

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