What does an error 'Got error 122 from storage engine' mean?

This error generally indicates an issue with disk space on the web server.  The mysql database needs to have space to add records, make temporary files, etc.  There are two possible causes of the problem:

1.  Disk quotas - your provider might put a quota on your total space, OR on the mysql database size.  Either one could cause your mysql instance to run out of space. 

2.  Filesystem is full - this means the physical disk or filesystem used by mysql is out of space. 

Fixing the disk space issue should immediately fix the problem, however any records you tried to add recently may not have been added.  You should verify database integrity once the disk space issue is resolved.