Fresh install of CentOS 6 on a test box, ran following as root:
yum install mysql-server #success
service mysqld start #success
service mysqld stop #success
cd /var/lib/
cp -rp mysql mysql.bak
rm -rf mysql
cp -rp mysql.bak mysql
service mysqld start
MySQL Daemon failed to start.
cat mysqld.log
/usr/libexec/mysqld: Can't find file: './mysql/plugin.frm' (errno: 13)
ls -l
drwxr-xr-x. 4 mysql mysql 4096 May 1 13:26 mysql
drwxr-xr-x. 4 mysql mysql 4096 May 1 13:23 mysql.bak
Directories are the same
diff -r mysql mysql.bak
No differences
ls -lR mysql > out1
ls -lR mysql.bak > out2
diff out1 out2
No differences
I also looked manually and every file in mysql vs mysql.bak has the same ownership mysql:mysql & same permissions.
Ive seen the previous SO issue like this, but that didn't help.
Any ideas?