binary log bug in percona5.5

today ,i changed my DB binary log dir,when i restart percoan5.5.21,i find the DB still read binary log in old dir instead of new dir

my solution is :

create a Symbol link,then start mysql,and remove the link.

and one more things, i often find the following info in error log,is this a bug?

120326 16:49:21 [Note] /usr/sbin/mysqld: ready for connections.
Version: ‘5.5.21-55-log’ socket: ‘/var/lib/mysql/mysql.sock’ port: 3306 Percona Server (GPL), Release rel25.0, Revision 227
120326 16:56:45 [ERROR] /usr/sbin/mysqld: Incorrect key file for table ‘/tmp/#sql_21b2_0.MYI’; try to repair it
120326 16:56:45 [ERROR] Got an error from unknown thread, /home/jenkins/workspace/percona-server-5.5-rpms/label_exp/ce ntos5-64/target/BUILD/Percona-Server-5.5.21-rel25.0/Percona
120326 16:56:45 [ERROR] /usr/sbin/mysqld: Sort aborted: Error writing file ‘/tmp/MYK74Kpi’ (Errcode: 28)

Neither of these things is a bug. Item 1 is misconfiguration and item 2 is you running out of disk space.