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Windows 7: chkdsk....allocation unit

27 Nov 2011   #1
fluidmotion

Win7 Starter 32 bits
 
 
chkdsk....allocation unit

Ran chkdsk on USB Hard disk drive.
what is allocation unit in this disk?




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-chkdsk.allocation.unit.png  
My System SpecsSystem Spec
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27 Nov 2011   #2
zigzag3143

Win 8 Release candidate 8400
 
 

Quote   Quote: Originally Posted by fluidmotion View Post
Ran chkdsk on USB Hard disk drive.
what is allocation unit in this disk?
Allocation unit is the size of the blocks on the HD. DO you mean what size is the allocation unit, or something else?
My System SpecsSystem Spec
27 Nov 2011   #3
fluidmotion

Win7 Starter 32 bits
 
 

what's the difference between disk space and allocation unit?

Quote   Quote: Originally Posted by zigzag3143 View Post
Quote   Quote: Originally Posted by fluidmotion View Post
Ran chkdsk on USB Hard disk drive.
what is allocation unit in this disk?
Allocation unit is the size of the blocks on the HD. DO you mean what size is the allocation unit, or something else?
My System SpecsSystem Spec
.


27 Nov 2011   #4
zigzag3143

Win 8 Release candidate 8400
 
 

Quote   Quote: Originally Posted by fluidmotion View Post
what's the difference between disk space and allocation unit?

Quote   Quote: Originally Posted by zigzag3143 View Post
Quote   Quote: Originally Posted by fluidmotion View Post
Ran chkdsk on USB Hard disk drive.
what is allocation unit in this disk?
Allocation unit is the size of the blocks on the HD. DO you mean what size is the allocation unit, or something else?
DIsk space free is the total the HD has free, allocation units tell you how many units x the number of units for the same figure. Only useful for more complex things.
My System SpecsSystem Spec
28 Nov 2011   #5
Corazon

Windows 7 Professional SP1 32-bit
 
 

Blocks, or sectors, on the HD are determined by the HD itself and have traditionally always been 512 bytes.

So-called AF (advanced format) drives are an exception as they have actual 4096-byte sectors, but often still use block addressing based on a 512-byte sector size to be compatible with current OSes.

The allocation unit size as reported by Windows is a filesystem feature and is the same as the cluster size. By default, clusters on an NTFS filesystem are 8 sectors each, or 4096 bytes (4k).

In your case, you're using the exFAT filesystem and a cluster size of 256KB. This is unusually big and will lead to a lot of lost disk space if you're storing many small files on the drive, but it does give a slight performance boost with sequential reading/writing of very large files.
My System SpecsSystem Spec
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 chkdsk....allocation unit




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