Art Alexion on 12 Dec 2008 13:07:37 -0800


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Re: [PLUG] Dell Mini 9 loses 2 GB SSD


On Friday 12 December 2008 3:48:18 pm Sean Cummins wrote:
> On Fri, Dec 12, 2008 at 2:00 PM, James Barrett <jadoba@jadoba.net> wrote:
> > On Fri, Dec 12, 2008 at 10:15 AM, Art Alexion <art.alexion@gmail.com>
> >
> > wrote:
> > > I think I understand now.  I use fdisk to create a 16 GB partition, but
> >
> > with
> >
> > > mkfs I only create a 14 GB file system.  Is that what you are saying?
> >
> > Yes, that is what I was trying to say.  I do not know for a fact if
> > that is what is happening, however.
>
> That sounds like a pretty good theory to me -- that the filesystem isn't
> occupying 100% of the space available in the partition.
>
> Just thought I'd also point out that the 16GB SSD is probably a bit less
> than 16GB... It's standard practice for marketing folks in the storage
> industry to publish capacity numbers using "marketing" / base 10 numbers.
> They take the total available space on the drive in bytes, and divide by
> 1,000 three times (and then generally round up a bit) to produce the
> capacity in GB.  But to derive the true usable capacity in
> base2/"engineering"/GiB numbers, you need to divide by 1,024 instead of
> 1,000.  The difference isn't all that significant for small drives.. but
> it's becoming much more noticable with larger drives (1TB+), and large
> arrays (100s-1000s of TBs).
>
> To get a good feel for what the real usable capacity will be, take the
> number in GB and multiply by 1000 three times, then divide by 1024 three
> times.  This isn't quite exact due to the marketing roundup factor, but it
> should be pretty close.  E.g. the 300GB FC drives that EMC sells -- the
> marketing number is really 299.76 (which is derived from the cylinder count
> on the drive).  The engineering number (GiB) is 279.17.
>
> Without knowing the cylinder count/size or the real marketing number, you
> can do a rough marketing->engineering conversion --
> 300*1000*1000*1000=300000000000 / 1024/1024/1024 = 279.39GiB -- that's very
> close to the actual usable capacity of 279.17GiB.
>
> So for the 16GB SSDs... 16*1000*1000*1000=16000000000 /1024/1024/1024 =
> 14.9GiB.  Subtract the Dell 256MB partition from this, and you have
> 14.65GiB remaining.
>

I'm thinking its James' theory, but I have lent it out and can't check now.  I 
can't figure out why Dell would ship it with a file system less than the 
partition capacity, but they really seem to be screwing this model up from 
marketing vs. availability, to a weird repository setup, to not maintaining 
that repository, and then doing Ubuntu installs that take up most of the SSD.

I work in a Dell shop, but we are buying the eees for these loaners.  Much 
better in terms of hardware, and the ubuntu-eee installs and configures 
nicely.

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