Last night I made a test for making a comparison between ext2, ext3 and reiser file systems about missing (!) disk spaces.
Basically I created 3 disk partitions with 1 gb size and formatted them with ext2, ext3 and reiser file system types. Then mounted them to folders same with filesystem names. The result df -h output is as below:
Filesystem Size Used Avail Use% Mounted on
/dev/sdb1 1004M 20K 953M 1% /ext2_fs
/dev/sdb2 1004M 17M 937M 2% /ext3_fs
/dev/sdb3 1020M 33M 988M 4% /reiser_fs
As you can see both ext2 and ext3 file systems are reserved 50 megabytes at 1 gigabyte disk partition.
This means 5% of disk is missing!!!
Calm down, here is the reason: (man tells everything to us )