To determine if you need to troubleshoot the Zend DBi MySQL start up, you should first try to:
If the ZENDDBID job will not start, you will often see some message (after a bit of digging around) that states “Object not found. Object is /tmp/mysql.sock.” It seems natural to assume that this file is needed for the start up, and it might be missing because of some problem with the installation, or maybe it got deleted. It is a natural assumption, but it is wrong. The mysql.sock file is created whenever the daemon starts, and is deleted whenever the daemon ends. The start up program checks to see if mysql.sock exists. If it does, that indicates a successful start up. If it does not exist, that indicates the start up failed. If mysql.sock is missing, it just tells us the daemon failed to start. It does not really tell us why.
So, with that little misunderstanding out of the way, how do we find out what the problem is. We have ways to get some better error reporting, but before we go through all that, I have found it worthwhile to go through some of the more common issues first. These issues are very easy to check. It only takes a few minutes to go through and check them all, and I can honestly not think of one single Zend DBi MySQL start up failure that was not due to one of these, so it is well worth the time to check them out.
My troubleshooting procedure is to go through each of the common problems one at a time, quickly eliminating them until I find the one that is preventing the start up. Then I fix that problem. If none of the common problems should turn out to be the issue, I have a couple of steps that can help provide more error information. None of the following steps is dependent on any other, so they can be done in any order. This is just the order in which I do them, believing this to be the fastest way, on average, to find and fix the problem. These issues are also not mutually exclusive. You can have more than one. If you fix one problem, but the daemon still will not start, leave the fix in place and continue researching the remaining steps.