> Source: [sk115862](https://support.checkpoint.com/results/sk/sk115862)

# sk115862 - Some disk space is unaccounted in the output of "df" command

| Property | Value |
|----------|-------|
| Solution ID | sk115862 |
| Date Created | 2017-02-09 |
| Last Modified | 2017-02-12 |
| Technical Level | Advanced |
| Products | Security Gateway, Security Management Server |
| Versions | R82.10, R82, R81.20, R82.10, R82, R81.20, R82.x, R82.20 |
| OS | Gaia |

## Symptoms

- Some disk space is unaccounted in the output of "df" command.
*Example* :

```

[Expert@HostName:0]# df -h | grep -E "Size|/var/log"
Filesystem            Size  Used Avail Use% Mounted on
                      10T   3.5T 6.1T  37%  /var/log
[Expert@HostName:0]#
```

Avail = (Size) - (Used) = (10T) - (3.5T) = 6.5T, and not 6.1T - i.e., 400G is unaccounted

## Cause

This is the design of the **`ext2 / ext3 / ext4`** file systems.

Quote from <https://linux.die.net/man/8/mkfs.ext2>:
> `-m `*reserved-blocks-percentage*   
> ` Specify the percentage of the filesystem blocks reserved for the super-user. This avoids fragmentation, and allows root-owned daemons, such as syslogd(8), to continue to function correctly after non-privileged processes are prevented from writing to the filesystem. The default percentage is 5%.`

## Solution

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