Folks,

Few days back I bought 500 GB Seagate Sata disk drive. I actually got only 459 GB but it's ok.

Issue started after that. I created 3 partitions in it using "fdisk" utility.
/dev/sdb1 15GB - ext3
/dev/sdb2 2GB - swap
/dev/sdb3 442GB - ext3

I then formated the first and last partitions using following commands:
# mke2fs -j /dev/sdb1
# mke2fs -j /dev/sdb3

However on mounting these two partitions, df -h shows following status:
Filesystem Size Used Avail Use% Mounted on
/dev/sdc2 17G 7.5G 8.1G 49% /
/dev/sdb3 442G 105M 420G 1% /mnt
/dev/sdb1 15G 70M 14G 1% /temp

As you can see under "Used" column the space used is 105 M and under "Avail" column the space left is only 420 GB so where is the remaining 22 GB? I have not copied any data on it. The two partitions are freshly formated partitions. I checked it through windows as well and the sizes are same. Please help.

If you are using one of the journaled filesystems, such as ext3 or reiserfs, the system reserves about 5% for root purposes.

5% of 442 GB is a little over 22 GB.

You can adjust the size of the journal space using tune2fs -j for ext3 systems and reiserfstune for reiserfs systems.

By default when a ext2/3 file system is created 5% is reserved for root. This is supposed to reduce fragmentation as well as allow root to login in case the file system becomes full. Use tune2fs to reduce the amount of reserved space.

I think it's space reserved for root.

from the mke2fs man page.

-m reserved-blocks-percentage
Specify the percentage of the filesystem blocks
reserved for the super-user. This value defaults
to 5%.

Thanks all...the sizes are back in business :

Filesystem Size Used Avail Use% Mounted on
/dev/sdc2 17G 7.5G 8.1G 49% /
/dev/sdb3 442G 105M 442G 1% /mnt
/dev/sdb1 15G 70M 15G 1% /temp