If you get an error of the following type for some queries, it means that MySQL cannot create a temporary file for the result set in the temporary directory:
Can't create/write to file '\\sqla3fe_0.ism'.
The preceding error is a typical message for Windows; the Unix message is similar.
C:\temp directory must exist and have
sufficient space for the MySQL server to write to. See
Section 18.104.22.168, “Using Option Files”.
Another cause of this error can be permissions issues. Make
sure that the MySQL server can write to the
Check also the error code that you get with perror. One reason the server cannot write to a table is that the file system is full:
$> perror 28 OS error code 28: No space left on device
If you get an error of the following type during startup, it indicates that the file system or directory used for storing data files is write protected. Provided that the write error is to a test file, the error is not serious and can be safely ignored.
Can't create test file /usr/local/mysql/data/master.lower-test