According to wikipedia.org/wiki/Ext3#Journaling_levels, there are 3 "Journaling levels" for Ext3:

Journal (lowest risk)
Both metadata and file contents are written to the journal before being committed to the main file system.

Ordered (medium risk)
Only metadata is journaled; file contents are not, but it's guaranteed that file contents are written to disk before associated metadata is marked as committed in the journal.

Writeback (highest risk)
Only metadata is journaled; file contents are not. The contents might be written before or after the journal is updated. As a result, files modified right before a crash can become corrupted.


Are there 3 choices for Ext4, and when do I make them?
During "mke2fs -t ext4 /deb/sdxx", or after installing the OS, maybe with tune2fs?.

You read https://en.wikipedia.org/wiki/Ext3, why not read https://en.wikipedia.org/wiki/Ext4 (or https://www.kernel.org/doc/Documenta...stems/ext4.txt) also? To determine what journaling option is suitable check the amount of data loss that could occur due to data not (yet) being written out to medium due to unclean shutdowns like for example a power failure. And yes, you may specify the journaling option during mkfs and tune2fs.