"Site Offline" MySQL server failing to start and stop
OMG !!! Look at the output of df -h

Size: 20G Used: 19G Available 0 Use Percent: 100%


YOU HAVE NO DISK SPACE !!! 

Get more diskspace freed up or have linode increase diskspace.

According to MySQL 5.0 Certification Study Guide


Page 408,409 Section 29.2 Bulletpoint 11 says:


  If you run out of disk space while adding rows to a MyISAM table, no
  error occurs. The server suspends the operation until space becomes
  available, and then completes the operation.


In reality, mysqld is not dead. It is waiting for free diskspace to continue whatever it normally does. Even during startup, if mysqld makes a temp table, it is a MyISAM table. No space left on the disk? No problem. MyISAM just patiently waits for you to make free space.

If you have an error file like /var/log/mysql/log, clear its contents like this:

echo -n &gt; /var/log/mysqld.log


If the error file in /var/lib/mysql/my-machine.err then do this:

echo -n &gt; /var/lib/mysql/my-machine.err


Give it a Try !!!