Linux/Unix systems use inode numbers, instead of file names, to identify files.
For the system, files names are alias or nicknames of inode numbers for the convenience of identification.
On the face of it, users open files using file names. But the process within the system involves three steps:
First, the system locates the inode number matching the file name.
Second, the system retrieves the inode information using the inode number.
At last, the system locates the block where the file data is stored based on the inode information and read the data.
Since each file must have an inode, it is possible that inode has been used up, but when the hard disk is not fully stocked, it is not possible to create a new file on the hard disk, this is the purpose of this monitor; view the total number of inodes per hard disk partition and the number already used, you can use DF-I.
If you want to view the size of each inode node, you can use sudodumpe2fs-h/hda | grep "inode size ".