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