An inode is an internal structure that the operating system
uses to track and control information about a file,
such as size and last access date.
Each file uses one inode.
When a filesystem runs out of inodes,
the system displays the following error message:
NOTICE: type: Out of inodes on type dev hd (major/minor)
where type is the filesystem type and
major/minor is the major and minor device
numbers (for example hd (1/42) for the
The initial allocation of inodes assumes a
ratio of about four data blocks per inode.
If the filesystem contains mostly files that are
smaller than four blocks, it runs out of inodes.
The number of inodes available on a filesystem is determined
when you create the filesystem using
If the filesystem consistently runs out of free inodes,
you can reconfigure the filesystem and increase the number of inodes.
This procedure destroys the information on your hard disk.
Do not use mkfs without first creating a
complete and verified backup.