problem while unmounting a disk

[Jyothi]

hi   i am facing problem while unmounting a mounted disk.   the disk is configured as raid1 and  mounts as /home while booting the system.  i have not opened any other session than the session i am using to execute the command 'umount /dev/md1' But system shows that /home is busy. i have no idea where home is used. i am in / directory and have not opened any file under /home. Any help will be appriciated   thanks Jyothi