When you run the find command on the root directory of a system you may want to exclude all network filesystems and confine your search to only your local machine. The benefits of this are obvious as it will save you a great amount of time especially if the mounted filesystem is very large.

Luckily the find command provides this ability with the ‘-xdev‘ or ‘-mount‘ options.

For example:

$ find / -xdev -name myfile.txt

This command will recursively search for myfile.txt starting in your root directory and skip all externally mounted filesystems.

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As a security measure the ext3 file system reserves 5% of device space for administrative processes. This protects the system by allowing root processes to continue using the disk if a user process runs wild and fills it up. With today’s larger disk capacities, 5% equates into gigabytes of arguably wasted space. Thankfully with the tune2fs command you can reduce this percentage and free most if not all of the reserved space.

The tune2fs command utility operates exclusively on ext2/ext3 file systems.

To run these commands you must run the command as root or use sudo.

You can run tune2fs on the ext3 partition with the ‘-l‘ option to show you all the filesystem details. The important information to focus on are the “Reserved block count” and “Block size” lines. Multiply these lines together to see how many bytes are currently reserved on the filesystem.

$ tune2fs -l /dev/sda1

...
Reserved block count:     1929908
...
Block size:               4096
...

That’s more than 7GB of space that is reserved.

Run the df command to see the current used space on the device before you make any changes.

$ df -h

Filesystem            Size  Used Avail Use% Mounted on
/dev/sda1             145G  3.1G  135G   3% /

Run the tune2fs command to change your reserved block percentage. The ‘-m‘ option sets the new reserved percentage.

In this example I am setting the percentage to 0 and completely removing the reserved space. This will effectively disable the security feature but free the most space. You may choose to reduce the reserved percentage instead in order to preserve the security benefit while still freeing some space.

$ sudo tune2fs -m 0 /dev/sda1

You can confirm the changes have taken effect by viewing the filesystem details.

$ tune2fs -l /dev/sda1

...
Reserved block count:     0
...

You can directly see the changes by looking at your system disk space usage. We now have an additional 7GB available.

$ df -h

Filesystem            Size  Used Avail Use% Mounted on
/dev/sda1             145G  3.1G  142G   3% /

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The ext3 file system forces an fsck once it has been mounted a certain number of times. By default this maximum mount count is usually set between 20-30. On many systems such as laptops which can be rebooted quite often this can quickly become a problem. To turn off this checking you can use the tune2fs command.

The tune2fs command utility operates exclusively on ext2/ext3 file systems.

To run these commands you must run the command as root or use sudo. You must also make sure that your filesystem is unmounted before making any changes. If you are doing this on your root partition the best solution is to use a LiveCD.

You can run tune2fs on the ext3 partition with the ‘-l‘ option to view what your current and maximum mount count is set to currently.

tune2fs -l /dev/sda1

...
Mount count:              2
Maximum mount count:      25
...

To turn off this check set the maximum count to 0 with the ‘-c‘ option.

# tune2fs -c 0 /dev/sda1

If you do not want to completely disable the file system checking, you can also increase the maximum count.

# tune2fs -c 100 /dev/sda1

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