[CentOS] EXT4 mount issue

[Miguel Medalha]

Can you give us the output of "tune4fs -l /dev/sdb" ?

Does it show " has_journal" under "Filesystem features"?

If it doesn't, you can input the following:

tune4fs -o journal_data

The option "journal_data" fits the case in which you don't care about 
the fastest speed but you put your focus on data integrity instead.

By the way, if you only used the defaults when creating the ext4 
filesystems, I am afraid that you didn't use the ext4 specific features 
that give it a real advantage over ext3. Some of them cannot be 
configured latter, they have to be specified when you create the filesystem.