Yesterday was one of those days when things that can go wrong went wrong and today was MySQL day, and problem when accessing any table on a live site resulted in following error
MySQL Error - Can't create/write to file '/tmp/#sql_7d3f_0.MYI' (Errcode: 30)
It took me some time to figure out that the error was due to /usr/tmpDSK getting corrupted, and and not really a problem with MySQL or our database as we were thinking all this time, and as usual google came to rescue.
Here are the steps to fix this for cpanel users… run the following commands in the order mentioned
/bin/umount -l /tmp
/bin/umount -l /var/tmp
/bin/rm -fv /usr/tmpDSK
This will create a new /tmp partition for you and the problem will go away. By the way error code 30 means that file system is read only.