-1

I have 1TB of hard disk and I don't know why but only 930gb is usable and then I have 4 partition 3 NTFS and 1 for Linux they all have 2-6gb less storage than there actual size ie: Linux partition have 300gb but there only 293gb is usable windows partition eat 4gb for no reason is there any solution for this

Kartik
  • 11
  • 7
  • The cause is likely the same reasons as the ones in https://superuser.com/questions/71974/why-is-the-effective-hard-drive-size-lower-than-the-actual-size – lungj Jul 18 '17 at 03:32
  • lungi, it's not a matter of windows eating up space. – Overmind Jul 18 '17 at 05:57

2 Answers2

3

I have 1TB of hard disk and I don't know why but only 930gb is usable

Incorrect. You have 1 TB (1,000 GB) of hard disk space but only 930GiB are usable. The "i" is important. 1 TB = 1,000,000,000,000 Bytes. 1TiB = 1,099,511,627,776 Bytes. That means that 1 Terabyte = about 931 Gibibytes.

The problem is that Hard Drive manufacturers use Giga- and Tera- and Mega- to label their hard drives. Meanwhile, your operating system uses Gibi- and Tebi- and Mebi- to label the same drives. This is a well-known source of confusion for consumers.

I imagine the rest are similar issues.

Cliff Armstrong
  • 2,266
  • 1
  • 10
  • 18
  • 1
    In addition not every program (especially older ones) identify their usage of MiB by using MiB as the unit but rather just just MB because who'd use the SI units in powers of ten in a computer system (with the exception of networking)? ;) – Seth Jul 18 '17 at 05:53
1

Manufacturers use 10-base numbers to state sizes of their disks. If you look at any modern HDD is written on it something like 1TB = 1.000.000.000.000 bytes. This is currently a marketing tactic. The superior unit of the byte in computer world is 1024 bytes (2^10), not 1000 (10^2). Computers use binary, not decimal and 1 TB of true computer data will be 1.099.511.627.776 bytes.

Therefore, 1.000.000.000.000 bytes of hard drive decimal size will be the equivalent of 930 GB of actual HDD space, as 1.099.511.627.776 bytes would be the equivalent of 1 TB.

Now to avoid confusion, some prefer to use KiB, MiB and so forth when referring the 1024 system.

Here's how advertised space vs. true usable space is like on current HDDs:

A/T
12/10.9 TB
10/9.09 TB
8/7.27 TB   
6/5.45 TB   
5/4.54 TB
4/3.63 TB   
3/2.72 TB   
2/1.81 TB   
1.5/1.36 TB 

1000/931 GB 
750/698 GB  
640/596 GB
500/465 GB  
320/298 GB  
250/232 GB  
200/186 GB  
160/149 GB
120/111 GB  
80/74 GB

Make sure to take this into account when investing is specific storage space.

Overmind
  • 9,924
  • 4
  • 25
  • 38
  • It's not just a preference though. "Kibibyte" (or **ki**lo-**bi**nary-**byte**) is the correct term for 2^10 bytes. Same for the rest of them. Your assertion that 1TB = 1,099,511,627,776 bytes is actually incorrect. 1TB = 1,000,000,000,000 bytes just as the HDD manufacturers claim... marketing tactic or not. :-/ – Cliff Armstrong Jul 18 '17 at 07:19
  • It's the current accepted form, but I don't agree with this absurdity. The I.S. should be used as justification for marketing. – Overmind Jul 18 '17 at 07:24
  • "the currently accepted form"... you make it sound like it's some fashion trend. It's not. We're not going to change kilograms to mean 1024 grams. It makes no sense to count grams in base-2 (binary). Kilo- is and will remain a base-10 prefix. As it should. Anything else really would be absurd. – Cliff Armstrong Jul 18 '17 at 07:38
  • I was referring strictly to bytes. That won't change either for old operating systems. This should have a case-specific definition, like many other things, which is way more simple than adding 'i's everywhere. – Overmind Jul 18 '17 at 07:48
  • There’s a reason RAM and such are measured in powers of 2, as this is how they’re organized. With hard disks, no such need exists to get an even number from it, so keeping the original S.I. units is a lot more reasonable. Operating systems should show file sizes and free/used *disk* space in S.I. units and no confusion would arise. Except for the seldom used case you dump your RAM (e.g. 8GiB) to disk and the file is now 8.5 GB) – Ro-ee Jul 18 '17 at 07:59
  • You mean the operating systems that almost no one uses anymore and thus aren't really a factor? The migration to having "i"s every where already happened. It happened 5-6 years ago. It started 5-6 years before that. There is not an OS on the market today that uses base-10 prefixes. There is not an OS still supported by its developer that uses base-10 prefixes. Going *back* would be far harder than staying where we are... and completely pointless. – Cliff Armstrong Jul 18 '17 at 08:08
  • So now you want to make things more confusing by having two different definitions of megabyte used in two different places in the same computer? Come on... this has now skipped passed absurd and into "clown-car silly" territory. And for the record, hard drives are addressed in base-2. Even old hard drives used 512 byte sectors and modern ones use 4096 byte sectors. SSDs have always been in base 2 and are labeled with base-2 prefixes. We haven't used a storage media with base-10 addressing since I got into computer 20 years ago. – Cliff Armstrong Jul 18 '17 at 08:10
  • Cliff, you are confused. In any OS, a KB is 1024, not 1000. Renaming all that with 'i' in the middle is just plain stupid. That's the actual point here. No, not 2 definitions of multiple of byte used. Definition specific for bytes. Of course everything is base-2. That's exactly why we should not mock things up instead of making a general rule. Let's detail this in a chat if you want. – Overmind Jul 18 '17 at 09:12