System Background: I am running CentOS 7 in a VM (in VirtualBox) on a host computer running Windows 10. My /dev/sda is on an SSD and then I have three 1TB HDDs /dev/sdb, /dev/sdc, and /dev/sdd configured into a RAID 5 drive called /dev/md5. The /dev/md5 is formatted as ext4 and is mounted to /raid5.

I wanted to bind mount both /home and /var to sub-directories in my RAID 5, /dev/md5.

The following steps worked just fine for /home:

mkdir /raid5/home
rsync -av /home/*/raid5 /home
mount --bind /raid5/home /home

nano /etc/fstab
/raid5/home /home none bind 0 0

I then restart CentOS and it boots no problem. I check df -aTh and both /raid5/home and /home show mounted to /dev/md5.

I follow the exact same process to bind mount /var and /raid5/var and upon reboot I can't even get to the login screen. Same exact commands were used, just substitute /var everywhere you see /home.

Any ideas why this worked for /home and not for /var?

FYI, I just started using CentOS/Linux last weekend so I only have 1 week of experience so far. I'm familiar with a lot of the Terminal commands, partitioning, formatting, and mounting drives, installing software, etc. I'm not as familiar with the file/directory permissions (I have a gut feeling when I bind /var to /raid5/var some important software is no longer able to access directories it needs).

if you can get into your system to where you can comment out that line, then boot into it, when you add to fstab, do you issue
where if their is an issue you will see it in the terminal, no issue it should work. if you have an issue you can fix it before rebooting the system, as far a RAID and bind mounting, i have no idea. I do not use RAID.