HDD size


D

Dragon

I thought I understood HDD size but perhaps not!
Have a used 2.5 HDD in USB enclosure.
Label says 4.86gb
Format as NTFS and it shows as 4.02gb
As FAT 32 as 4.01gb
Understand (I think) about 1000 versus 1024 as kilo etc.
At gb level that gives a factor of 1.074 (1.024 cubed)
That gets the 4.02 up to 4.32.
Checking the disk under XP shows nothing wrong.
Where is the rest?

Henry
 
D

Dave (from the UK)

Dragon said:
I thought I understood HDD size but perhaps not!
Have a used 2.5 HDD in USB enclosure.
Label says 4.86gb
Format as NTFS and it shows as 4.02gb
As FAT 32 as 4.01gb
Understand (I think) about 1000 versus 1024 as kilo etc.
At gb level that gives a factor of 1.074 (1.024 cubed)
That gets the 4.02 up to 4.32.
Checking the disk under XP shows nothing wrong.
Where is the rest?

Henry
My guess is Windoze will need to use some space to keep track of the files. Each
file will have a name - the characters on that name will take up some bytes, but
don't detract from the amount of space available. Date / time of modification,
creation, access permissions etc all need space. So space has to be found for
data structures that keep information about the files.

Each file will probably have more than one block on the disk. Exactly what
blocks make up the file need to be stored.

All this information takes up space, so a file system will have less available
than the raw disk.

I don't know about Windoze, but on UNIX you can tune the file system to get more
space if you know there will be few files by having less inodes.

Also on UNIX systems, the amount of space reported free is that available to
normal users. The 'root' user has a bit more space. Perhaps windoze does this to.

Are you overlooking the swap file?

Just ideas.

--
Dave K MCSE.

MCSE = Minefield Consultant and Solitaire Expert.

Please note my email address changes periodically to avoid spam.
It is always of the form: month-year@domain. Hitting reply will work
for a couple of months only. Later set it manually.
 
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R

Rod Speed

Dragon said:
I thought I understood HDD size but perhaps not!
Certainly not.
Have a used 2.5 HDD in USB enclosure.
Label says 4.86gb
Format as NTFS and it shows as 4.02gb
As FAT 32 as 4.01gb
Thats just the different space occupied by the directory structures.
Understand (I think) about 1000 versus 1024 as kilo etc.
At gb level that gives a factor of 1.074 (1.024 cubed)
That gets the 4.02 up to 4.32.
Checking the disk under XP shows nothing wrong.
Where is the rest?
Used for the directory structures, fats etc.
 
D

Dragon

Rod Speed said:
Certainly not.


Thats just the different space occupied by the directory structures.


Used for the directory structures, fats etc.
Is that still true when I've put no directories/folders or files on the
drive?
The arithmetic I did on my main drive seems to come out right without a
missing half gig.
Also worked OK on a nominal 20gb drive in a USB enclosure.
Could some of the drive be 'bad blocks' or whatever and no longer available?
It's quite an old drive.
DBCA-204860 from 1999

Henry
 
R

Rod Speed

I meant that about just the last two lines above.
Is that still true when I've put no directories/folders or files on the
drive?
Yes, there is quite a bit of that even with no files or folders added.

Most obviously with the FATs which occupys the same space
regardless of whether there are any files and folders on the drive.

Its more complicated with NTFS but the same thing still applys.
The arithmetic I did on my main drive seems to come out right without a
missing half gig.
Yes, but the FATs and other directory structures still need to be there.
Also worked OK on a nominal 20gb drive in a USB enclosure.
Not clear if you mean that drive doesnt have half a gig 'missing' or not.
Could some of the drive be 'bad blocks' or whatever and no longer
available?
Nope, those should be invisible.
It's quite an old drive. DBCA-204860 from 1999
It shouldnt have half a gig of bads unless its dying.
 
E

Eric Gisin

Does Disk Managment show the drive as 4.52GB?
Is there free space after the primary partition?
 
D

Dragon

Eric Gisin said:
Does Disk Managment show the drive as 4.52GB?
Is there free space after the primary partition?
Disk management shows 4.02gb with no unallocated space.
 
E

Eric Gisin

Dragon said:
Disk management shows 4.02gb with no unallocated space.
There could have been a 4GB BIOS limit/bug 10 years ago.
If so, some drives would have a 4GB limit jumper.
 
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D

Dragon

Rod Speed said:
I meant that about just the last two lines above.



Yes, there is quite a bit of that even with no files or folders added.

Most obviously with the FATs which occupys the same space
regardless of whether there are any files and folders on the drive.

Its more complicated with NTFS but the same thing still applys.


Yes, but the FATs and other directory structures still need to be there.


Not clear if you mean that drive doesnt have half a gig 'missing' or not.


Nope, those should be invisible.


It shouldnt have half a gig of bads unless its dying.
The 20gb disk shows as 18.6gb as I would expect from the 1.074 conversion.
If I add up the reported used and free space it comes to 18.6gb
The byte count is reported as 20gb. which matches the advertised capacity.
So there is no missing half a gig.and that has lots of files on it.

The 4.86 gb doesn't match the same arithmetic and that has no files on it.
Reported bytes are 4.3 gb as I calculated from the 4.02 reported size.

I've done the same arithmetic on several other drives and all 'add up' OK.
Well there is one exception that goes the other way!
An '80gb' Maxtor 6Y/080L0 adds up to 82gb in manufacturers parlance or 76.3
in XP.

Now I'm even more confused!
 
D

Dragon

Eric Gisin said:
There could have been a 4GB BIOS limit/bug 10 years ago.
If so, some drives would have a 4GB limit jumper.
I've tried the drive as Fat 32 and NTFS.
Tried on 2 desktops and a laptop with a mixture of XP and ME (one of the
desktops)
Same capacity(almost) shown in all cases.
No sign of a place for a jumper.

Henry
 
R

Rod Speed

The 20gb disk shows as 18.6gb as I would expect from the 1.074
conversion. If I add up the reported used and free space it comes to
18.6gb
OK, I assumed you were just using the
free space, not the used and free added.
The byte count is reported as 20gb. which matches the advertised
capacity. So there is no missing half a gig.and that has lots of files on
it.
The 4.86 gb doesn't match the same arithmetic and that has no files on
it. Reported bytes are 4.3 gb as I calculated from the 4.02 reported
size.
Looks like its got short stroked somehow. Thats a way
of getting the drive to report a smaller size than it actually
is and is done with software, and is set in the drive itself.
It may have got done when it was used in a system which
has a problem with drives over 4GB with binary GBs.

You should be able to reverse that using Hitachi's Drive Feature Tool.
Hitachi bought out IBM's hard drive operation and its an IBM drive.
I've done the same arithmetic on several other drives and all 'add up'
OK.
Yeah, they should do if you use the sum of free and used space reported.
Well there is one exception that goes the other way!
An '80gb' Maxtor 6Y/080L0 adds up to 82gb in manufacturers parlance or
76.3 in XP.
Some manufacturers have rounded down the stated size
to a nice decimal number and that is one of those drives. In
other words its an 82GB drive stated as 80GB for simplicity.
160,086,528 sectors, 512 bytes each, 81,964,302,336 bytes, 82GB, decimal
GBs.

http://maxtor.com/_files/maxtor/en_us/documentation/manuals/diamondmax_plus_9_manual.pdf
Now I'm even more confused!
Its not quite as bad as it looks.
 
D

Dragon

Thanks for all that Rod,
I'll have a look at the Hitachi site for the tool tomorrow.
It will be interesting to find out whether it can see a USB connected disk.
Otherwise I'll put on a 2.5/3.5 adapter and attach to IDE.

Cheers

Henry
 
D

Dragon

Dragon said:
I thought I understood HDD size but perhaps not!
Have a used 2.5 HDD in USB enclosure.
Label says 4.86gb
Format as NTFS and it shows as 4.02gb
As FAT 32 as 4.01gb
Understand (I think) about 1000 versus 1024 as kilo etc.
At gb level that gives a factor of 1.074 (1.024 cubed)
That gets the 4.02 up to 4.32.
Checking the disk under XP shows nothing wrong.
Where is the rest?
Lots of helpful suggestions but only one was right!

Downloaded Hitachi Drive Feature Tool and set the capacity to full.
As it's a laptop drive had to use an adaptor to connect to IDE as the toll
only looks at IDE drives.
At some time in its history it had been reduced.

Credit goes to Rod Speed who suggested the reason and the cure.
Thanks very much Rod.

Thanks to others for trying.

Henry
 
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R

Rod Speed

Lots of helpful suggestions but only one was right!
Downloaded Hitachi Drive Feature Tool and set the capacity to full.
As it's a laptop drive had to use an adaptor to connect to IDE as the
toll only looks at IDE drives.
At some time in its history it had been reduced.
Credit goes to Rod Speed who suggested the reason and the cure.
Thanks very much Rod.
Thanks for the feedback.
 

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