Tune2fs allows to change inode size from default (128 bytes on ext3, 256 bytes on ext4) to almost anything, but it should be power of two. What are the reasons for changing default inode size?
Here it's written that this can be done to be able to store ACL attributes inside inodes. What else can be stored inside an inodes?
Is there any reason to increase inode size on modern high-capacity drives (2TB and more)?