Used Space on C vs Size on Disk of Folders/files on C

[Guest Alan C. Brown]

I have just re-installed WinXP Pro SP2 from a Toshiba Recovery CD and

updated to XP Pro SP3 on my Toshiba Satellite Pro M70 laptop.

 

When I click My Computer it shows :

 

Local Disk C:

Toal Size - 19.9 GB

Free Space - 10.2 GB

 

Used Space - 9.70 GB

 

However when I right click on Local Disk C: & select explore, and then

highlight all the folders in the right pane of Windows expoler,and click on

properties, the info I get is :

 

44,671 Files, 2630 folders

Sze: 6.14GB

Size on disk: 6.04GB

 

Therefore there is a difference of 3.66GB (9.70 - 6.04) between the Used

Space and Size on Disk.

 

Question is why ?

 

Is this normal ?

 

Thank you

 

Alan C.Brown

[Guest Brian Cryer]

Re: Used Space on C vs Size on Disk of Folders/files on C

 

 

"Alan C. Brown" <acbrown@intnet.mu> wrote in message

news:%23zeKMiA4IHA.1204@TK2MSFTNGP04.phx.gbl...

>I have just re-installed WinXP Pro SP2 from a Toshiba Recovery CD and

>updated to XP Pro SP3 on my Toshiba Satellite Pro M70 laptop.

>

> When I click My Computer it shows :

>

> Local Disk C:

> Toal Size - 19.9 GB

> Free Space - 10.2 GB

>

> Used Space - 9.70 GB

>

> However when I right click on Local Disk C: & select explore, and then

> highlight all the folders in the right pane of Windows expoler,and click

> on properties, the info I get is :

>

> 44,671 Files, 2630 folders

> Sze: 6.14GB

> Size on disk: 6.04GB

>

> Therefore there is a difference of 3.66GB (9.70 - 6.04) between the Used

> Space and Size on Disk.

>

> Question is why ?

 

Firstly there is a reason why the "Size" and "Size on disk" are different.

Space on disks is allocated in chunks which is a whole number of sectors, so

each file occupies a given number of sectors. Now the sector size can vary,

but assuming a 4KB sector size (which is what it is on my pc but they can

vary) then any file less than 4KB will take up a single sector. So if my

file is only 10 bytes long then the majority of that 4KB is going to waste.

On average each file will "waste" half a sector, so in my case I loose about

2KB for each file. Applying that to your case, 44,671 files would loose

about 2KB*44671 = 87MB which is quite close to the 0.1GB (100GB) which is

the difference beween 6.14 and 6.04GB you have reported.

 

As for the difference between the "size" of 6.14GB and the "Used space"

figure of of 9.70GB. Normally I would expect the figures to be other other

way round with the total "Size" larger thant he reported "Used space". On my

pc the "size" is 128GB and the "Used space" is only 119GB, this is because

disk capacity is measured assuming 1GB = 1,000,000,000 bytes whereas file

sizes are calculated assuming that 1GB=2^30bytes = 1,073,741,824.

 

The reason (and now finally we come to the answer you are after) why your

"Used space" is larger than your total file "Size" is almost certainly

because windows hiding hidden and system files from you and that these are

therefore not included in the total. If in Windows Explorer you go tools >

Options and on the "View" tab select to show hidden files and folders and

protected operating system files, then I would expect your "Used space"

figure to increase.

> Is this normal ?

 

Yes.

> Thank you

 

You're welcome.

--

Brian Cryer

http://www.cryer.co.uk/brian

[Guest Alan C. Brown]

Re: Used Space on C vs Size on Disk of Folders/files on C

 

Did as you instructed and selected show hidden files and folders and show

hidden protected operating system files, and now with all the folders &

files highlighted in the C: partition, clicking on properties gives:

 

44,793 Files, 2649 Folders

Size: 9.21GB (9,892,328,944 bytes)

Size on disk: 9.10Gb (9,779,005,832 bytes)

 

Therefore the difference between Size (9.21GB) and Used Space (9.70GB) has

been reduced to 0.49GB (from 3.66GB) - so that explains most of the

difference originally observed. Wonder what the remaining 0.49GB difference

is due to.

 

I'm amazed at the size/size on disk/used space, considering I've only

installed 82MB of applications.

 

Confirm that I'm getting Size > Size on Disk (always thought it was supposed

to be the other way around (i.e. with Size on Disk = Size + wasted space).

 

Thanks for your help.

 

Alan C. Brown

 

"Brian Cryer" <not.here@localhost> wrote in message

news:%23tlSl8B4IHA.1192@TK2MSFTNGP05.phx.gbl...

>

> "Alan C. Brown" <acbrown@intnet.mu> wrote in message

> news:%23zeKMiA4IHA.1204@TK2MSFTNGP04.phx.gbl...

>>I have just re-installed WinXP Pro SP2 from a Toshiba Recovery CD and

>>updated to XP Pro SP3 on my Toshiba Satellite Pro M70 laptop.

>>

>> When I click My Computer it shows :

>>

>> Local Disk C:

>> Toal Size - 19.9 GB

>> Free Space - 10.2 GB

>>

>> Used Space - 9.70 GB

>>

>> However when I right click on Local Disk C: & select explore, and then

>> highlight all the folders in the right pane of Windows expoler,and click

>> on properties, the info I get is :

>>

>> 44,671 Files, 2630 folders

>> Sze: 6.14GB

>> Size on disk: 6.04GB

>>

>> Therefore there is a difference of 3.66GB (9.70 - 6.04) between the Used

>> Space and Size on Disk.

>>

>> Question is why ?

>

> Firstly there is a reason why the "Size" and "Size on disk" are different.

> Space on disks is allocated in chunks which is a whole number of sectors,

> so each file occupies a given number of sectors. Now the sector size can

> vary, but assuming a 4KB sector size (which is what it is on my pc but

> they can vary) then any file less than 4KB will take up a single sector.

> So if my file is only 10 bytes long then the majority of that 4KB is going

> to waste. On average each file will "waste" half a sector, so in my case I

> loose about 2KB for each file. Applying that to your case, 44,671 files

> would loose about 2KB*44671 = 87MB which is quite close to the 0.1GB

> (100GB) which is the difference beween 6.14 and 6.04GB you have reported.

>

> As for the difference between the "size" of 6.14GB and the "Used space"

> figure of of 9.70GB. Normally I would expect the figures to be other other

> way round with the total "Size" larger thant he reported "Used space". On

> my pc the "size" is 128GB and the "Used space" is only 119GB, this is

> because disk capacity is measured assuming 1GB = 1,000,000,000 bytes

> whereas file sizes are calculated assuming that 1GB=2^30bytes =

> 1,073,741,824.

>

> The reason (and now finally we come to the answer you are after) why your

> "Used space" is larger than your total file "Size" is almost certainly

> because windows hiding hidden and system files from you and that these are

> therefore not included in the total. If in Windows Explorer you go tools >

> Options and on the "View" tab select to show hidden files and folders and

> protected operating system files, then I would expect your "Used space"

> figure to increase.

 

I'm amazed at the size/size on disk/used space, considering I've only

installed 82MB of applications.

>

>> Is this normal ?

>

> Yes.

>

>> Thank you

>

> You're welcome.

> --

> Brian Cryer

> http://www.cryer.co.uk/brian

>

>

[Guest Ken Blake, MVP]

Re: Used Space on C vs Size on Disk of Folders/files on C

 

On Mon, 7 Jul 2008 11:49:31 +0100, "Brian Cryer" <not.here@localhost>

wrote:

> Firstly there is a reason why the "Size" and "Size on disk" are different.

> Space on disks is allocated in chunks which is a whole number of sectors, so

> each file occupies a given number of sectors. Now the sector size can vary,

> but assuming a 4KB sector size (which is what it is on my pc but they can

> vary) then any file less than 4KB will take up a single sector. So if my

> file is only 10 bytes long then the majority of that 4KB is going to waste.

> On average each file will "waste" half a sector, so in my case I loose about

> 2KB for each file. Applying that to your case, 44,671 files would loose

> about 2KB*44671 = 87MB which is quite close to the 0.1GB (100GB) which is

> the difference beween 6.14 and 6.04GB you have reported.

 

 

Although what you say is generally correct, note that space is

allocated in units called "clusters," not sectors.

 

On hard drives, sector size is fixed at 512 bytes. Cluster size, on

NTFS volumes is normally 4K, but on a FAT32 volume, it varies with the

size of the volume.

 

--

Ken Blake, Microsoft MVP - Windows Desktop Experience

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