Starting MySQL 5.1 with different datadir

I do regularly change the data directory from the default /var/lib/mysql to something else like /var/lib/mysql1 It works wihtout any is开发者_开发问答sues on 5.0

On 5.1 version of Mysql, it fails to start once I change the datadir with the following message...

Starting MySQL.Manager of pid-file quit without updating file.[FAILED]

I have already created the new directory and changed it's permission. Anything else must be going wrong and I can not figure it out.

Update:

There are 2 error messages in the error log.

[ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.

[ERROR] Fatal error: Can't open and lock privilege tables: Table 'mysql.host' doesn't exist

Have you moved all the files and directories from old location to new one? If no - that is what you have to do now.