Linux -- adjusting root reserve and other stuff for an EXT4 partition, tune4fs , e4fsprogs package

As you may remember, I had a blog post about the root reserve on Linux ext* filesystems, http://ermanarslan.blogspot.com.tr/2014/09/linux-tune2fs-adjusting-reserved-blocks.html.

Today, tried it on a ext4 filesystem residing on an Oracle VM Server based Virtual disk in a Customer test environment and the result was;

[root@oracleserver TEST]# df -h

Filesystem            Size  Used Avail Use% Mounted on

/dev/xvda2            9.3G  4.4G  4.9G  48% /

/dev/xvda1            487M   27M  435M   6% /boot

tmpfs                 4.0G     0  4.0G   0% /dev/shm

/dev/xvdb1            197G  187G     0 100% /u01

/dev/xvdb1            197G  187G     0 100% /ortest

[root@oracleserver TEST]# tune2fs -m 2 /dev/xvdb1
tune2fs 1.39 (29-May-2006)
tune2fs: Filesystem has unsupported feature(s) while trying to open /dev/xvdb1
Couldn't find valid filesystem superblock.

This was actually expected. 

These kind of stuff on ext4 filesystem should be done using tune4fs. (not the tune2fs)

So, as you see below, using tune4fs everything went fine;

[root@oracleserver TEST]# tune4fs -r 0 /dev/xvdb1

tune4fs 1.41.12 (17-May-2010)

Setting reserved blocks count to 0

[root@oracleserver TEST]# df -h

Filesystem            Size  Used Avail Use% Mounted on

/dev/xvda2            9.3G  4.4G  4.9G  48% /

/dev/xvda1            487M   27M  435M   6% /boot

tmpfs                 4.0G     0  4.0G   0% /dev/shm

/dev/xvdb1            197G  187G   10G  95% /u01

/dev/xvdb1            197G  187G   10G  95% /ortest

tune4fs is available via e4fsprogs package.

e4fsprogs also brings other tools for playing with ext4 filesystem. Here is a short list ;

4fsck ->used to repair filesystem inconsistencies after an unclean shutdown

mke4fs->used to initialize a partition to contain an empty ext4 filesystem) 

debugfs -> used to examine the internal structure of a filesystem, to manually repair a corrupted filesystem, or to create test cases for e4fsck)

tune4fs -> (used to modify filesystem parameters) and etc..

Lastly, altough it is not documented(or I couldnt have time to check all the web:)) , e4fsprogs package is just a newer version of e2fsprogs. In this manner tune4fs is the newer version of tune2fs.

At the bottom line, tune4fs and all the other **4fs programs delivered within the e4fsprogs can deal with the ext4 filesystem.