Linked by Thom Holwerda on Fri 19th Oct 2012 20:07 UTC
Windows Interesting little tidbit from the Reddit AMA session with Microsoft's Surface team. One Redditor wondered just how much disk space Windows RT takes up - in other words, if you buy the 32GB Surface RT tablet, how much space is left for your stuff? It turns out that while Windows 8 RT is considerably smaller than its Windows 7 x86 predecessor, it's still huge by mobile standards.
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RE[3]: Not quite true
by tanzam75 on Sat 20th Oct 2012 02:02 UTC in reply to "RE[2]: Not quite true"
tanzam75
Member since:
2011-05-19


So a 120GB SSD does actually have 120GB of storage but you're only allowed to fill ~120GB as the remainer is there purely for load wearing.



That the 7% overprovisioning factor happens to be the same as the difference between GiB and GB is a nice coincidence. But it's just that -- a coincidence.

The coincidence disappears when you look at drives that have RAISE. See, e.g., the 960 GB OWC Mercury Electra MAX 3G SSD: http://www.anandtech.com/show/6038/owc-releases-960gb-mercury-elect...

It has 1024 GiB of raw capacity, and 894 GiB of formatted capacity. The difference is not 7% but 14% -- and it's because some of the raw capacity is reserved for RAISE as well as overprovisioning.

They're advertising this as a 960 GB drive (= 894 GiB), not as a 1024 GB or a 1 TB drive. In other words, they're not advertising the raw capacity in binary prefixes, but the formatted capacity in decimal SI prefixes.

Magnetic hard drives also had a higher raw capacity than formatted, as did floppy disks. Because the difference wasn't anywhere close to the 5% difference between MiB/MB or the 2.4% difference between KiB/KB, the urban legend did not have a chance to spawn as it did with SSDs.

(Trick question: Why are 1.44 MB floppies called that? They're neither 1.44 decimal MB, nor 1.44 binary MiB, nor 1440 decimal KB, nor 1440 binary KiB.)

Edited 2012-10-20 02:15 UTC

Reply Parent Score: 3