Is it normal for ext3 and ext4 to have "lost space", ie space reported by the system as "free" but "not available"?

On my system, I have one partition for Windows XP formatted NTFS. One /home partition, formatted ext3, and the Linux filesystem formatted ext4 (I created my separate /home partition before ext4 came along).

My system monitor is showing the NTFS partition as 10.9GB free, 10.9GB available; a memory stick I have mounted at the moment (vfat) is showing 7.7GB free and available. But the ext3 filesystem shows 1.1GB free but only 573.8MB available. The ext4 filesystem shows 13GB free but only 12.1GB available.

Is this lost space the penalty you pay for using ext3/4 filesystems, or does this lost space represent bad sectors? I am nervous about using any disk analysis or repair tools, as I am aware that one wrong move could be disastrous!

Does anyone have any advice? Thank you.

By default ext2/3/4 filesystems reserve 5% for root which looks like lost space. Reserved space is supposed to reduce fragmentation as well as allow root to log in if the filesystem becomes full. You can use tune2fs to reduce reserved space and it is safe to reduce it to zero if not /.

Thank you for this information, it did not occur to me that this had something to do with the fragmentation resistance of ext. I looked up tune2fs and now know a lot more about this.

Thanks.
Steve