Mysql gives me:“Can't open and lock privilege tables: Table 'host' is read only”

Question

I am facing problem restoring the mysql database. My primary database was mysql5.1 and now I am trying to copy it to mysql5.5. The database was backed by using Xtrabackup .

I am using Ubuntu 12.04.3 LTS on this server, mysql version is : 5.5.32-0ubuntu0.12.04.1-log

I have followed all the steps to restore using Xtrabackup , this created database files, which I have copied to a tmp directory.

I have modified my.cnf to point to this tmp directory. I have changed the tmp directory permissions and changed the ownership of the files to mysql user. drwxr-xr-x 12 mysql mysql 4096 Sep 10 10:04 base

Now when I start the mysql server I get this error "[ERROR] Fatal error: Can't open and lock privilege tables: Table 'host' is read only"

I have given a try as follows:

1. Even tried installing mysql5.1 to see if that was the issue.
2. tried 'chcon mysql_db_t' to change the context but it gives me "can't apply partial context to unlabelled file"
3. I have used --skip-grant to get into database, but using this I can only access innodb tables only, MyIsam tables throw read-only error
4. After --skip-grant, I have used upgrade_mysql this throws me error that many tables are read-only.
5. I have removed apparmor too. and restarted too.
6. I have restored a different database(5.1 to 5.5) previously on Ubuntu 12.04.2 LTS without any issues.

Can some please point me in right direction, I am not sure whats wrong with permissions.

Thanks in advance.

Answer 1

Answering my own question,

The issue is with AppArmor. I am not sure why MySql is unable to access files even after uninstalling AppArmor.

Reinstalled AppArmor and moved the MySql profile under disabled profiles of AppArmor, even then it did not work.

I copied the database files under /var/lib/mysql/ and MySql stopped throwing errors