I keep getting this error in my email.

<div style="border:2px solid red;padding:4px;width:600px;margin:0px auto;">

                    <div style="text-align:center;background-color:red;color:white;font-weight:bold;">Error</div>

                    <div style="text-align:center;">Database connect failed</div>

                            </div>

I repaired the database, but I get this often.

This is not a problem with the database but a problem with the database server.  Check the resource settings for the database server, it may be failing to connect because the server is maxed out with connections or other things.

I think you are right. Disk is at 94% full.

A problem with the disk being full would generate a different error.

Database connect failed is normally a caused by either the database server being down, to many connections, under high load, ect and is quite common on low end servers, shared hosting where the host has limited the resources. Especially during nightly cron runs. The disk full is not a good thing either, but not likely the cause of that specific error message.

 It is in the cron daemon.