pointing datadir to a mounted device

[Matt Lawton]

Hi,

I need to change the default data directory for a new installation of mysql 5.0. The default is /var/lib/mysql, and everything works using this datadir. However, after shutting down mysqld I copied the files from this directory to a directory on a mounted disk, making sure the file owners and modes were all retained, then changed /etc/mysql/my.cnf to have datadir = new directory on mounted drive. When I try to restart mysqld (using mysqld_safe), or when I reboot, mysqld fails to start because a test to see if it can write to the datadir directory fails. I know this by checking the syslog.

As far as I can tell, the ownership and file permissions are exactly the same for the new directory as for /var/lib/mysql. If I change /etc/mysql/my.cnf to point datadir back to /var/lib/mysql it works fine. Is there something about using a mounted device that is not the root device that is not allowed?? Any other suggestions?

Thanks in advance,
Matt.