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August 30th, 2009

Snow Leopard fixes disk capacity bug

Posted by Robin Harris @ 2:12 pm

Categories: Disk drives, Software

Tags: Disk, Capacity, Storage, Hardware, Robin Harris

When will Microsoft follow?
It is a common question: why does my computer say a 1,000 GB drive is only 932 GB? What happened to the other 68 GB I paid for?

Actually, you have every byte you bought. But because operating systems report storage capacity in base 2 rather than the official base 10 the numbers look short.

And as drives get bigger, the “shortage” gets bigger:

Table from Your capacity will vary

Main memory is measured in base 2 as well - 1 KB of RAM is actually 1024 bytes - because most processors access memory in base 2 chunks - 8, 16, 32 or 64 bits - and it simplifies the internal math to use the same base 2 that the processor uses.

But disks are just a box of bytes that can be formatted many different ways. For example, a vendor can choose to store data in 20-bit chunks - 16 for data and 4 for extra ECC - which reduces the available capacity but not the raw capacity that disk vendor shipped.

The Apple fix
In Snow Leopard MacOS 10.6 storage capacity is now reported the way storage vendors specify it: in base 10. Snow Leopard will report the same capacity that the drive vendor shipped.

Of course, some capacity is used for formatting and other capacity may be used for files that are normally kept invisible. But at least the capacity the operating system reports and the capacity you thought you were buying will now match.

The Storage Bits take
Over the last 25 years, ever since hard drives started becoming common on PCs, curious users have been confused by the capacity reporting anomaly. Apple’s simple fix is one small but important step towards making data storage user friendly.

Some may argue that this wasn’t a bug, that the reporting was correct and the people wrong. But that isn’t the way it works in a consumer-driven world: if it isn’t right for the people using the system, it isn’t right. Get over it.

Update: Many commenters are arguing that mega, giga, tera etc. are base 2 metrics. Sorry for shouting but YOU ARE WRONG!

SI, IEC and IEEE have all specified, some starting over 10 years ago, that mega, giga, tera etc. are base 10 metrics. If you want base 2 you need to specify it with prefixes like kibi.

So man up, flush your stale cache and join the 21st century. I’ll ignore the slurs on my credibility for now, but don’t let it happen again. End update.

Comments welcome, of course. That’s right, officially MB is base 10, while MiB is base 2. Read the official Apple knowledge base article here.

Robin HarrisRobin Harris has been messing with computers for over 30 years and selling and marketing data storage for over 20 in companies large and small. See his full profile and disclosure of his industry affiliations.

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  • Talkback
  • Most Recent of 69 Talkback(s)
Get the case right
What about the morons that insist on using "K" when they mean "k" and "m" when they mean "M"? Talk about being off by a few percentage points! Let's see... 10mb vs. 10Mb - 0.010 vs 10,000,000: 100000000000%!

(That goes for the people that write 10mHz, or worse 10mhz, as well).... (Read the rest)
Posted by: jimtzdnet Posted on: 08/31/09 You are currently: a Guest | | Terms of Use
a step backwards *NEW*  javajunkie@... | 08/30/09
True the world today *NEW*  Richard Flude | 08/30/09
What is Truth, grasshopper? *NEW*  Robin HarrisZDNet Moderator | 08/30/09
Garbage bug *NEW*  javajunkie@... | 08/31/09
Actually the true answer is to report the actual... *NEW*  mrlinux | 08/31/09
Should be deleted... *NEW*  wolf_z | 08/31/09
it is a dilemma, not a bug *NEW*  shis-ka-bob | 08/31/09
Because it's false advertising *NEW*  voska1 | 08/31/09
not a bug *NEW*  darthstupid | 08/30/09
RE: Snow Leopard fixes disk capacity bug *NEW*  ZDnet Reader 43 | 08/30/09
RE: Snow Leopard fixes disk capacity bug *NEW*  nathanmiller | 08/30/09
But files don't come in pre-set capacities *NEW*  Robin HarrisZDNet Moderator | 08/30/09
Apple has introduced a bug... *NEW*  wolf_z | 08/31/09
What IT person? *NEW*  NeoGeneration | 08/31/09
I'm usually right in line with your thinking, but here  *NEW*  chrome_slinky@... | 08/30/09
But no one is lying! Base 2 is Swahili. *NEW*  Robin HarrisZDNet Moderator | 08/30/09
Swahili speaker may find that offensive *NEW*  Richard Flude | 08/30/09
If I were an English-speaking buyer, yes. *NEW*  Robin HarrisZDNet Moderator | 08/31/09
Robin you are speaking to the rigid! *NEW*  mlindl | 08/31/09
mlindl, you support lying? *NEW*  wolf_z | 08/31/09
So who is lying now? *NEW*  jasonp@... | 08/31/09
The hard drive manufacturers, ofc. *NEW*  NeoGeneration | 08/31/09
Are they "defending" *NEW*  jasonp@... | 08/31/09
Look, somebody with a big white T-Shirt that says *NEW*  NeoGeneration | 08/31/09
It's an honest lie *NEW*  voska1 | 08/31/09
Swahili - not if it's what you've been speaking forever... *NEW*  Timpraetor | 08/31/09
RE: Snow Leopard fixes disk capacity bug *NEW*  amingin | 08/31/09
Lol. Precisely. Posts like this completely undermine RH's credibility... *NEW*  ibarskiy@... | 08/31/09
Industry's wrong *NEW*  jragosta | 08/31/09
Fix what? There is no problem to begin with, *NEW*  NeoGeneration | 08/31/09
Lol. Precisely. Posts like this completely undermine RH's credibility... *NEW*  ibarskiy@... | 08/31/09
100% agreed. ZDNet would rather market spin and non-substance... *NEW*  HypnoToad72 | 08/31/09
RE: Snow Leopard fixes disk capacity bug *NEW*  prw3505 | 08/31/09
About roots... *NEW*  amingin | 08/31/09
Sheesh... *NEW*  jragosta | 08/31/09
Simple practice *NEW*  amingin | 08/31/09
Silly *NEW*  jragosta | 08/31/09
Time is the most important thing *NEW*  amingin | 08/31/09
Why wait? *NEW*  jragosta | 08/31/09
Newsflash! *NEW*  amingin | 08/31/09
ROTFLMAO *NEW*  jragosta | 08/31/09
RE: Snow Leopard fixes disk capacity bug *NEW*  digglife | 08/31/09
Amazing *NEW*  jragosta | 08/31/09
This isn`t about a name, it`s about the entire sistem. *NEW*  NeoGeneration | 08/31/09
Go ahead *NEW*  jragosta | 08/31/09
Much ado about nothing. *NEW*  jpdemers@... | 08/31/09
Consumer! *NEW*  amingin | 08/31/09
Wrong *NEW*  jragosta | 08/31/09
Point *NEW*  amingin | 08/31/09
Of course *NEW*  jragosta | 08/31/09
KB, MB, GB, TB, PB, EB are not SI units... *NEW*  wolf_z | 08/31/09
Yes! *NEW*  amingin | 08/31/09
Amazing *NEW*  jragosta | 08/31/09
Wow. *NEW*  nathanmiller | 08/31/09
Re: Amazing *NEW*  jragosta | 08/31/09
And again... *NEW*  amingin | 08/31/09
I think it's great... *NEW*  Sleeper Service | 08/31/09
what's the complain? *NEW*  patibulo | 08/31/09
One issue I see *NEW*  voska1 | 08/31/09
RE: Snow Leopard fixes disk capacity bug *NEW*  alkanshel | 08/31/09
Wrong. *NEW*  jragosta | 08/31/09
Apple BROKE it. Robin Harris is WRONG. *NEW*  lamps | 08/31/09
Name one thing *NEW*  jragosta | 08/31/09
What advantage do you get *NEW*  voska1 | 08/31/09
RE: Snow Leopard fixes disk capacity bug *NEW*  msdamico@... | 08/31/09
RE: Snow Leopard DOES NOT fixes disk capacity bug  *NEW*  peter.j.boyles@... | 08/31/09
RE: Snow Leopard fixes disk capacity bug *NEW*  supasmalls@... | 08/31/09
RE: Snow Leopard fixes disk capacity bug *NEW*  jpdemers@... | 08/31/09
Get the case right *NEW*  jimtzdnet | 08/31/09

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