# Strange df on external HDD



## SPlissken (Feb 3, 2010)

Hello all

I have an external 1,5 TB USB hard disk.
I have formated it with UFS2 and copied differents files on it.

df command show this


```
Filesystem  1K-blocks       Used      Avail Capacity  Mounted on 
/dev/da0s1  1419042678 1067768898 237750366    82%      /mnt/DD1
```

1067768898 (used) + 237750366 (free) = 1305519224 

Where is the difference 
1419042678 - 1305519224 = 113 523 454 (113 GB !!!!) 

Any explanation are welcome


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## vermaden (Feb 3, 2010)

Some math: 1305519224 / 1419042678 ~ 9.2%

*man newfs(8)*

```
-m free-space
	     The percentage of space reserved from normal users; the minimum
	     free space threshold.  The default value used is defined by
	     MINFREE from <ufs/ffs/fs.h>, currently 8%.
```
So by default you are not using about 8% of reserved space, the rest 1.2% (difference was 9.2%) is used by filesystem metadata/inodes.

Sollution: `# tunefs -m 0 -o time /dev/da0s1`


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## SPlissken (Feb 3, 2010)

Thanks, fast and clear answer


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## SirDice (Feb 3, 2010)

Also note the difference between the SI TB (10^12) and the binary TB (2^40).


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