Ext4

Ext4, or Fourth Extended File System, was introduced as a successor to Ext3. It featured a larger maximum volume size which was now 1 EiB. It was backwards compatible with ext2, and ext3, which allowed mounting of one to the other. It doubled the subdirectory limit, which is now 64,000. It also featured faster file system checking, in case something goes wrong, and you need your machine back up quicker.