I had large file 200GB in my ext2 disk, then I deleted it(three are no files in Trash). And I haven't gained any free space. I don't want to use fsck as it requres me to unmount disk. I were windows user for a long time, there I could scan disk without unmounting it, is there are similar posibility in Ubuntu 10? 
How can I fix linux disk without unmount it?
linux;filesystems;disk usage;fsck
Is the file a database file by chance or something that might be still open by a long running program or daemon?  Generally, if you didn't see a decrease in disk space it's most likely that something still has the file open.If it truly is the file system itself that is in error (which would be odd), I'm afraid you'll need to umount the disk to run fsck on it.