Ext4 Filesystem Performance Problem Due to Index Table Capacity

Applies to:   

Oracle Linux - Version 7 and later  

Symptoms 

Performance issues seen in an ext4 filesystem with a directory with a large number of files. 

/var/log/messages shows messages: 

...
[4499046.084695] EXT4-fs warning (device dm-3): ext4_dx_add_entry:2263: Directory (ino: 7192641) index full, reach max htree level :2 
[4499046.084696] EXT4-fs warning (device dm-3): ext4_dx_add_entry:2267: Large directory feature is not enabled on this filesystem 
...

Cause 

The maximum number of files in a directory index has been reached.

Solution 

There are multiple ways to address the directory index problem in ext4 filesystem: 

• delete unneeded files from that directory; 
• reorganize the content, separating the files into multiple directories;