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When attempting to relocate MySQL's data directory in Ubuntu Server 10.04, many developers encounter the frustrating "Error 13: Permission denied" message. This typically manifests when MySQL cannot access critical files like plugin.frm or ibdata1, indicating the service account lacks proper filesystem permissions.

First verify current MySQL configuration:

mysql --version
sudo cat /etc/mysql/my.cnf | grep datadir
ls -ld /var/lib/mysql

Key directories should show mysql:mysql ownership:

drwx------ 4 mysql mysql 4096 Aug 10 19:32 /var/lib/mysql

1. Stop MySQL service:

sudo service mysql stop

2. Copy existing data with proper permissions:

sudo cp -Rp /var/lib/mysql /new/path/data_directory

3. Update AppArmor configuration (critical for Ubuntu):

sudo nano /etc/apparmor.d/usr.sbin.mysqld

Add these lines under the existing directory rules:

/new/path/data_directory/ r,
/new/path/data_directory/** rwk,

4. Reload AppArmor:

sudo /etc/init.d/apparmor reload

Modify MySQL configuration file:

sudo nano /etc/mysql/my.cnf

Update the datadir parameter:

[mysqld]
datadir = /new/path/data_directory

Even on Ubuntu, check for residual SELinux contexts:

sudo apt-get install selinux-utils
sudo matchpathcon /new/path/data_directory

Set correct ownership recursively:

sudo chown -R mysql:mysql /new/path/data_directory
sudo chmod -R 750 /new/path/data_directory

Start MySQL and verify operation:

sudo service mysql start
mysql -u root -p -e "SHOW VARIABLES LIKE 'datadir'"

If issues persist, check error logs:

sudo tail -50 /var/log/mysql/error.log

For minimal downtime, consider symlinking instead of direct copy:

sudo service mysql stop
sudo mv /var/lib/mysql /new/path/data_directory
sudo ln -s /new/path/data_directory /var/lib/mysql
sudo service mysql start

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When attempting to relocate MySQL's data directory in Ubuntu Server 10.04, many administrators encounter the frustrating Errno 13 permission denied error. The key indicators in the error log are:

InnoDB: Operating system error number 13 in a file operation.
InnoDB: The error means mysqld does not have the access rights to
InnoDB: the directory.

Before proceeding with the solution, verify these critical points:

# Check current MySQL data directory
mysqladmin variables | grep datadir

# Verify directory ownership
ls -ld /path/to/new/datadir

# Confirm mysql user exists
grep mysql /etc/passwd

Here's the complete procedure to properly migrate your MySQL data directory:

# 1. Stop MySQL service
sudo service mysql stop

# 2. Create new directory (if needed)
sudo mkdir -p /new/data/path

# 3. Set proper ownership (critical step)
sudo chown -R mysql:mysql /new/data/path

# 4. Copy existing data (preserve permissions)
sudo cp -R -p /var/lib/mysql/* /new/data/path/

# 5. Update MySQL configuration
sudo nano /etc/mysql/my.cnf
# Locate [mysqld] section and modify:
datadir = /new/data/path

# 6. Update apparmor configuration (specific to Ubuntu)
sudo nano /etc/apparmor.d/usr.sbin.mysqld
# Add these lines:
/new/data/path/ r,
/new/data/path/** rwk,

# 7. Restart apparmor
sudo /etc/init.d/apparmor reload

# 8. Start MySQL
sudo service mysql start

After completing the migration, verify the changes:

# Check if MySQL is running
sudo service mysql status

# Verify new data directory
mysql -e "SELECT @@datadir;"

# Check for remaining permission issues
sudo tail -f /var/log/mysql/error.log

If you still encounter issues, try these additional steps:

# Repair tables (if needed)
sudo mysql_upgrade -u root -p

# Set SELinux context (if using SELinux)
sudo chcon -R -t mysqld_db_t /new/data/path

For some environments, using symbolic links might be preferable:

sudo service mysql stop
sudo mv /var/lib/mysql /new/data/path
sudo ln -s /new/data/path/mysql /var/lib/mysql
sudo chown -R mysql:mysql /new/data/path
sudo service mysql start