Backup Strategies (not relying on DBexport)

As our system continues to grow I am concerned with the integrity of the data in case of failures. Presently we are on Online 5.08 and are planning to migrate to 7.xx in a few months. I would like to simply use tbtape to do all my backups and restores and not rely on dbimport/dbexport. I am in a service bureau which adds a level of complexity to the system. It is possible for one agency's division to require a restore. I cannot restore individual databases (or spaces) in 5.x. Online 7.x solves the data space issues so I could place each agency's division in its own space. The problem is I need at least 800MB per division and the total number of divisions will eclipse 100. I don't want 80GB used for individual spaces nor do I want 100 spaces on the system. My current strategy is this: 1. Use tbtape on the 8mm to get everything in case of major failure. 2. DBexport the database to another disk on another controller. 3. tar & compress the previous day's data on that disk. 4. Backup that disk to a different tape drive. I think that strategy gives me enough redundancy in case of failure. However, I am concerned about the dbexport/dbimport comments from the manuals as I mentioned before. I've seen consultants set up import/export as the only backup strategy at colleagues' sites. How dangerous is this? I guess an experience last night where I received an error 28 while importing a new demostration database set off the "red flags". The system reported I was out of disk space; yet, I was no where near that condition (30% used of chunk number 1). I unloaded Informix, brought it up (it did a recovery), and the import worked. Has anyone experienced this? I'm concerned because of the migration to 7 if there are problems. That will not happen, however, until after I attend training on it. I read horror stories in this NG about that... Thanks in advance for any help. I think this is a "unique" situation and as more agencies come online I don't want to be caught in a bad situation. -t