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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.

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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?

>
> 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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