How do I move a MySQL data directory to an external hard drive?

I tried moving MySQL data directory to an external Hard disk (which has been formatted using NTFS).
I followed the steps given in the answer to the question How to change MySQL data directory?

• Stop MySQL

• Copy MySQL data directory to new location

• Edit the MySQL configuration file (update datadir variable).

• Update the new path in apparmor

• Reload apparmor

• Start MySQL (/etc/init.d/mysql restart)

But at the 6th step, when I restart MySQL it's failing. When I look into /var/log/mysql/error.log I get the following message:

2015-05-17 12:07:05 4317 [Warning] Can't create test file /media/prasanth/SeagateExpansionDrive/MWDatabase/mysql/ neo.lower-test

/usr/sbin/mysqld: Can't change dir to '/media/prasanth/SeagateExpansionDrive/MWDatabase/mysql/' (Errcode: 13 - Permission denied)

What should I do to fix this problem?

I guessed that it is because the mysql user does not have permissions to write to the directory on the external hard drive. So I tried to change the ownership of the entire path (chown mysql:mysql -R /media/prasanth/SeagateExpansionDrive/MWDatabase/mysql/). But it didn't get reflected.

So I tried mounting that partition again with sudo mount -t ntfs -o rw,auto,user,fmask=0022,dmask=0000 /dev/sdb1 /media/prasanth/SeagateExpansionDrive/ with no luck.

Setup Details:

Host - Ubuntu 14.04

External Drive: NTFS FileSystem, 4TB single partition

MySQL: mysqld Ver 5.6.19-0ubuntu0.14.04.1 for debian-linux-gnu on x86_64

The new directory must be accessible by mysqld. In step 2, did you copy all ownership and permissions?

But probably you started mysqld as a user without permissions to the new directory? Note that it can't even do a cd: "Can't change dir".

Check for SELinux or AppArmor being in the way.

StackExchange Database Administrators Q#101732, answer score: 3